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ActiveRecord::Base

Active Record objects don't specify their attributes directly, but rather infer them from the table definition with which they're linked. Adding, removing, and changing attributes and their type is done directly in the database. Any change is instantly reflected in the Active Record objects. The mapping that binds a given Active Record class to a certain database table will happen automatically in most common cases, but can be overwritten for the uncommon ones.

See the mapping rules in table_name and the full example in files/README.html for more insight.

Creation

Active Records accept constructor parameters either in a hash or as a block. The hash method is especially useful when you're receiving the data from somewhere else, like an HTTP request. It works like this:

user = User.new(:name => "David", :occupation => "Code Artist")
user.name # => "David"

You can also use block initialization:

user = User.new do |u|
  u.name = "David"
  u.occupation = "Code Artist"
end

And of course you can just create a bare object and specify the attributes after the fact:

user = User.new
user.name = "David"
user.occupation = "Code Artist"

Conditions

Conditions can either be specified as a string, array, or hash representing the WHERE-part of an SQL statement. The array form is to be used when the condition input is tainted and requires sanitization. The string form can be used for statements that don't involve tainted data. The hash form works much like the array form, except only equality and range is possible. Examples:

class User < ActiveRecord::Base
  def self.authenticate_unsafely(user_name, password)
    find(:first, :conditions => "user_name = '#{user_name}' AND password = '#{password}'")
  end

  def self.authenticate_safely(user_name, password)
    find(:first, :conditions => [ "user_name = ? AND password = ?", user_name, password ])
  end

  def self.authenticate_safely_simply(user_name, password)
    find(:first, :conditions => { :user_name => user_name, :password => password })
  end
end

The authenticate_unsafely method inserts the parameters directly into the query and is thus susceptible to SQL-injection attacks if the user_name and password parameters come directly from an HTTP request. The authenticate_safely and authenticate_safely_simply both will sanitize the user_name and password before inserting them in the query, which will ensure that an attacker can't escape the query and fake the login (or worse).

When using multiple parameters in the conditions, it can easily become hard to read exactly what the fourth or fifth question mark is supposed to represent. In those cases, you can resort to named bind variables instead. That's done by replacing the question marks with symbols and supplying a hash with values for the matching symbol keys:

Company.find(:first, :conditions => [
  "id = :id AND name = :name AND division = :division AND created_at > :accounting_date",
  { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' }
])

Similarly, a simple hash without a statement will generate conditions based on equality with the SQL AND operator. For instance:

Student.find(:all, :conditions => { :first_name => "Harvey", :status => 1 })
Student.find(:all, :conditions => params[:student])

A range may be used in the hash to use the SQL BETWEEN operator:

Student.find(:all, :conditions => { :grade => 9..12 })

An array may be used in the hash to use the SQL IN operator:

Student.find(:all, :conditions => { :grade => [9,11,12] })

Overwriting default accessors

All column values are automatically available through basic accessors on the Active Record object, but sometimes you want to specialize this behavior. This can be done by overwriting the default accessors (using the same name as the attribute) and calling read_attribute(attr_name) and write_attribute(attr_name, value) to actually change things. Example:

class Song < ActiveRecord::Base
  # Uses an integer of seconds to hold the length of the song

  def length=(minutes)
    write_attribute(:length, minutes.to_i * 60)
  end

  def length
    read_attribute(:length) / 60
  end
end

You can alternatively use self[:attribute]=(value) and self[:attribute] instead of write_attribute(:attribute, value) and read_attribute(:attribute) as a shorter form.

Attribute query methods

In addition to the basic accessors, query methods are also automatically available on the Active Record object. Query methods allow you to test whether an attribute value is present.

For example, an Active Record User with the name attribute has a name? method that you can call to determine whether the user has a name:

user = User.new(:name => "David")
user.name? # => true

anonymous = User.new(:name => "")
anonymous.name? # => false

Accessing attributes before they have been typecasted

Sometimes you want to be able to read the raw attribute data without having the column-determined typecast run its course first. That can be done by using the <attribute>_before_type_cast accessors that all attributes have. For example, if your Account model has a balance attribute, you can call account.balance_before_type_cast or account.id_before_type_cast.

This is especially useful in validation situations where the user might supply a string for an integer field and you want to display the original string back in an error message. Accessing the attribute normally would typecast the string to 0, which isn't what you want.

Dynamic attribute-based finders

Dynamic attribute-based finders are a cleaner way of getting (and/or creating) objects by simple queries without turning to SQL. They work by appending the name of an attribute to find_by_, find_last_by_, or find_all_by_, so you get finders like Person.find_by_user_name, Person.find_all_by_last_name, and Payment.find_by_transaction_id. So instead of writing Person.find(:first, :conditions => ["user_name = ?", user_name]), you just do Person.find_by_user_name(user_name). And instead of writing Person.find(:all, :conditions => ["last_name = ?", last_name]), you just do Person.find_all_by_last_name(last_name).

It's also possible to use multiple attributes in the same find by separating them with "and", so you get finders like Person.find_by_user_name_and_password or even Payment.find_by_purchaser_and_state_and_country. So instead of writing Person.find(:first, :conditions => ["user_name = ? AND password = ?", user_name, password]), you just do Person.find_by_user_name_and_password(user_name, password).

It's even possible to use all the additional parameters to find. For example, the full interface for Payment.find_all_by_amount is actually Payment.find_all_by_amount(amount, options). And the full interface to Person.find_by_user_name is actually Person.find_by_user_name(user_name, options). So you could call Payment.find_all_by_amount(50, :order => "created_on"). Also you may call Payment.find_last_by_amount(amount, options) returning the last record matching that amount and options.

The same dynamic finder style can be used to create the object if it doesn't already exist. This dynamic finder is called with find_or_create_by_ and will return the object if it already exists and otherwise creates it, then returns it. Protected attributes won't be set unless they are given in a block. For example:

# No 'Summer' tag exists
Tag.find_or_create_by_name("Summer") # equal to Tag.create(:name => "Summer")

# Now the 'Summer' tag does exist
Tag.find_or_create_by_name("Summer") # equal to Tag.find_by_name("Summer")

# Now 'Bob' exist and is an 'admin'
User.find_or_create_by_name('Bob', :age => 40) { |u| u.admin = true }

Use the find_or_initialize_by_ finder if you want to return a new record without saving it first. Protected attributes won't be set unless they are given in a block. For example:

# No 'Winter' tag exists
winter = Tag.find_or_initialize_by_name("Winter")
winter.new_record? # true

To find by a subset of the attributes to be used for instantiating a new object, pass a hash instead of a list of parameters. For example:

Tag.find_or_create_by_name(:name => "rails", :creator => current_user)

That will either find an existing tag named "rails", or create a new one while setting the user that created it.

Saving arrays, hashes, and other non-mappable objects in text columns

Active Record can serialize any object in text columns using YAML. To do so, you must specify this with a call to the class method serialize. This makes it possible to store arrays, hashes, and other non-mappable objects without doing any additional work. Example:

class User < ActiveRecord::Base
  serialize :preferences
end

user = User.create(:preferences => { "background" => "black", "display" => large })
User.find(user.id).preferences # => { "background" => "black", "display" => large }

You can also specify a class option as the second parameter that'll raise an exception if a serialized object is retrieved as a descendant of a class not in the hierarchy. Example:

class User < ActiveRecord::Base
  serialize :preferences, Hash
end

user = User.create(:preferences => %w( one two three ))
User.find(user.id).preferences    # raises SerializationTypeMismatch

Single table inheritance

Active Record allows inheritance by storing the name of the class in a column that by default is named "type" (can be changed by overwriting Base.inheritance_column). This means that an inheritance looking like this:

class Company < ActiveRecord::Base; end
class Firm < Company; end
class Client < Company; end
class PriorityClient < Client; end

When you do Firm.create(:name => "37signals"), this record will be saved in the companies table with type = "Firm". You can then fetch this row again using Company.find(:first, "name = '37signals'") and it will return a Firm object.

If you don't have a type column defined in your table, single-table inheritance won't be triggered. In that case, it'll work just like normal subclasses with no special magic for differentiating between them or reloading the right type with find.

Note, all the attributes for all the cases are kept in the same table. Read more: www.martinfowler.com/eaaCatalog/singleTableInheritance.html

Connection to multiple databases in different models

Connections are usually created through ActiveRecord::Base.establish_connection and retrieved by ActiveRecord::Base.connection. All classes inheriting from ActiveRecord::Base will use this connection. But you can also set a class-specific connection. For example, if Course is an ActiveRecord::Base, but resides in a different database, you can just say Course.establish_connection and Course and all of its subclasses will use this connection instead.

This feature is implemented by keeping a connection pool in ActiveRecord::Base that is a Hash indexed by the class. If a connection is requested, the retrieve_connection method will go up the class-hierarchy until a connection is found in the connection pool.

Exceptions

Note: The attributes listed are class-level attributes (accessible from both the class and instance level). So it's possible to assign a logger to the class through Base.logger= which will then be used by all instances in the current object space.

Constants

VALID_FIND_OPTIONS

Attributes

abstract_class[RW]

Set this to true if this is an abstract class (see abstract_class?).

Public Class Methods

===(object) click to toggle source

Overwrite the default class equality method to provide support for association proxies.

# File lib/active_record/base.rb, line 1488
def ===(object)
  object.is_a?(self)
end
abstract_class?() click to toggle source

Returns whether this class is a base AR class. If A is a base class and B descends from A, then B.base_class will return B.

# File lib/active_record/base.rb, line 1504
def abstract_class?
  defined?(@abstract_class) && @abstract_class == true
end
all(*args) click to toggle source

This is an alias for find(:all). You can pass in all the same arguments to this method as you can to find(:all)

# File lib/active_record/base.rb, line 638
def all(*args)
  find(:all, *args)
end
allow_concurrency() click to toggle source

Deprecated and no longer has any effect.

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 92
def allow_concurrency
  ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency has been deprecated and no longer has any effect. Please remove all references to allow_concurrency.")
end
allow_concurrency=(flag) click to toggle source

Deprecated and no longer has any effect.

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 97
def allow_concurrency=(flag)
  ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency= has been deprecated and no longer has any effect. Please remove all references to allow_concurrency=.")
end
attr_accessible(*attributes) click to toggle source

Specifies a white list of model attributes that can be set via mass-assignment, such as new(attributes), update_attributes(attributes), or attributes=(attributes)

This is the opposite of the attr_protected macro: Mass-assignment will only set attributes in this list, to assign to the rest of attributes you can use direct writer methods. This is meant to protect sensitive attributes from being overwritten by malicious users tampering with URLs or forms. If you'd rather start from an all-open default and restrict attributes as needed, have a look at attr_protected.

class Customer < ActiveRecord::Base
  attr_accessible :name, :nickname
end

customer = Customer.new(:name => "David", :nickname => "Dave", :credit_rating => "Excellent")
customer.credit_rating # => nil
customer.attributes = { :name => "Jolly fellow", :credit_rating => "Superb" }
customer.credit_rating # => nil

customer.credit_rating = "Average"
customer.credit_rating # => "Average"
# File lib/active_record/base.rb, line 1085
def attr_accessible(*attributes)
  write_inheritable_attribute(:attr_accessible, Set.new(attributes.map(&:to_s)) + (accessible_attributes || []))
end
attr_protected(*attributes) click to toggle source

Attributes named in this macro are protected from mass-assignment, such as new(attributes), update_attributes(attributes), or attributes=(attributes).

Mass-assignment to these attributes will simply be ignored, to assign to them you can use direct writer methods. This is meant to protect sensitive attributes from being overwritten by malicious users tampering with URLs or forms.

class Customer < ActiveRecord::Base
  attr_protected :credit_rating
end

customer = Customer.new("name" => David, "credit_rating" => "Excellent")
customer.credit_rating # => nil
customer.attributes = { "description" => "Jolly fellow", "credit_rating" => "Superb" }
customer.credit_rating # => nil

customer.credit_rating = "Average"
customer.credit_rating # => "Average"

To start from an all-closed default and enable attributes as needed, have a look at attr_accessible.

# File lib/active_record/base.rb, line 1052
def attr_protected(*attributes)
  write_inheritable_attribute(:attr_protected, Set.new(attributes.map(&:to_s)) + (protected_attributes || []))
end
attr_readonly(*attributes) click to toggle source

Attributes listed as readonly can be set for a new record, but will be ignored in database updates afterwards.

# File lib/active_record/base.rb, line 1095
def attr_readonly(*attributes)
  write_inheritable_attribute(:attr_readonly, Set.new(attributes.map(&:to_s)) + (readonly_attributes || []))
end
base_class() click to toggle source

Returns the base AR subclass that this class descends from. If A extends AR::Base, A.base_class will return A. If B descends from A through some arbitrarily deep hierarchy, B.base_class will return A.

# File lib/active_record/base.rb, line 1495
def base_class
  class_of_active_record_descendant(self)
end
benchmark(title, log_level = Logger::DEBUG, use_silence = true) click to toggle source

Log and benchmark multiple statements in a single block. Example:

Project.benchmark("Creating project") do
  project = Project.create("name" => "stuff")
  project.create_manager("name" => "David")
  project.milestones << Milestone.find(:all)
end

The benchmark is only recorded if the current level of the logger is less than or equal to the log_level, which makes it easy to include benchmarking statements in production software that will remain inexpensive because the benchmark will only be conducted if the log level is low enough.

The logging of the multiple statements is turned off unless use_silence is set to false.

# File lib/active_record/base.rb, line 1468
def benchmark(title, log_level = Logger::DEBUG, use_silence = true)
  if logger && logger.level <= log_level
    result = nil
    ms = Benchmark.ms { result = use_silence ? silence { yield } : yield }
    logger.add(log_level, '%s (%.1fms)' % [title, ms])
    result
  else
    yield
  end
end
colorize_logging click to toggle source

Determines whether to use ANSI codes to colorize the logging statements committed by the connection adapter. These colors make it much easier to overview things during debugging (when used through a reader like tail and on a black background), but may complicate matters if you use software like syslog. This is true, by default.

# File lib/active_record/base.rb, line 491
cattr_accessor :colorize_logging, :instance_writer => false
column_names() click to toggle source

Returns an array of column names as strings.

# File lib/active_record/base.rb, line 1317
def column_names
  @column_names ||= columns.map { |column| column.name }
end
columns() click to toggle source

Returns an array of column objects for the table associated with this class.

# File lib/active_record/base.rb, line 1303
def columns
  unless defined?(@columns) && @columns
    @columns = connection.columns(table_name, "#{name} Columns")
    @columns.each { |column| column.primary = column.name == primary_key }
  end
  @columns
end
columns_hash() click to toggle source

Returns a hash of column objects for the table associated with this class.

# File lib/active_record/base.rb, line 1312
def columns_hash
  @columns_hash ||= columns.inject({}) { |hash, column| hash[column.name] = column; hash }
end
configurations click to toggle source

Contains the database configuration - as is typically stored in config/database.yml - as a Hash.

For example, the following database.yml...

development:
  adapter: sqlite3
  database: db/development.sqlite3

production:
  adapter: sqlite3
  database: db/production.sqlite3

...would result in ActiveRecord::Base.configurations to look like this:

{
   'development' => {
      'adapter'  => 'sqlite3',
      'database' => 'db/development.sqlite3'
   },
   'production' => {
      'adapter'  => 'sqlite3',
      'database' => 'db/production.sqlite3'
   }
}
# File lib/active_record/base.rb, line 448
cattr_accessor :configurations, :instance_writer => false
connected?() click to toggle source

Returns true if ActiveRecord is connected.

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 127
def connected?
  connection_handler.connected?(self)
end
connection() click to toggle source

Returns the connection currently associated with the class. This can also be used to "borrow" the connection to do database work unrelated to any of the specific Active Records.

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 114
def connection
  retrieve_connection
end
connection_handler click to toggle source

The connection handler

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 13
class_attribute :connection_handler
connection_pool() click to toggle source
# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 118
def connection_pool
  connection_handler.retrieve_connection_pool(self)
end
content_columns() click to toggle source

Returns an array of column objects where the primary id, all columns ending in "_id" or "_count", and columns used for single table inheritance have been removed.

# File lib/active_record/base.rb, line 1323
def content_columns
  @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
end
count_by_sql(sql) click to toggle source

Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part. The use of this method should be restricted to complicated SQL queries that can't be executed using the ActiveRecord::Calculations class methods. Look into those before using this.

Parameters

  • sql - An SQL statement which should return a count query from the database, see the example below.

Examples

Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
# File lib/active_record/base.rb, line 918
def count_by_sql(sql)
  sql = sanitize_conditions(sql)
  connection.select_value(sql, "#{name} Count").to_i
end
create(attributes = nil, &block) click to toggle source

Creates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.

The attributes parameter can be either be a Hash or an Array of Hashes. These Hashes describe the attributes on the objects that are to be created.

Examples

# Create a single new object
User.create(:first_name => 'Jamie')

# Create an Array of new objects
User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }])

# Create a single object and pass it into a block to set other attributes.
User.create(:first_name => 'Jamie') do |u|
  u.is_admin = false
end

# Creating an Array of new objects using a block, where the block is executed for each object:
User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) do |u|
  u.is_admin = false
end
# File lib/active_record/base.rb, line 721
def create(attributes = nil, &block)
  if attributes.is_a?(Array)
    attributes.collect { |attr| create(attr, &block) }
  else
    object = new(attributes)
    yield(object) if block_given?
    object.save
    object
  end
end
decrement_counter(counter_name, id) click to toggle source

Decrement a number field by one, usually representing a count.

This works the same as increment_counter but reduces the column value by 1 instead of increasing it.

Parameters

  • counter_name - The name of the field that should be decremented.

  • id - The id of the object that should be decremented.

Examples

# Decrement the post_count column for the record with an id of 5
DiscussionBoard.decrement_counter(:post_count, 5)
# File lib/active_record/base.rb, line 1024
def decrement_counter(counter_name, id)
  update_counters(id, counter_name => -1)
end
default_timezone click to toggle source

Determines whether to use Time.local (using :local) or Time.utc (using :utc) when pulling dates and times from the database. This is set to :local by default.

# File lib/active_record/base.rb, line 498
cattr_accessor :default_timezone, :instance_writer => false
delete(id) click to toggle source

Deletes the row with a primary key matching the id argument, using a SQL DELETE statement, and returns the number of rows deleted. Active Record objects are not instantiated, so the object's callbacks are not executed, including any :dependent association options or Observer methods.

You can delete multiple rows at once by passing an Array of ids.

Note: Although it is often much faster than the alternative, #destroy, skipping callbacks might bypass business logic in your application that ensures referential integrity or performs other essential jobs.

Examples

# Delete a single row
Todo.delete(1)

# Delete multiple rows
Todo.delete([2,3,4])
# File lib/active_record/base.rb, line 779
def delete(id)
  delete_all([ "#{connection.quote_column_name(primary_key)} IN (?)", id ])
end
delete_all(conditions = nil) click to toggle source

Deletes the records matching conditions without instantiating the records first, and hence not calling the destroy method nor invoking callbacks. This is a single SQL DELETE statement that goes straight to the database, much more efficient than destroy_all. Be careful with relations though, in particular :dependent rules defined on associations are not honored. Returns the number of rows affected.

Parameters

  • conditions - Conditions are specified the same way as with find method.

Example

Post.delete_all("person_id = 5 AND (category = 'Something' OR category = 'Else')")
Post.delete_all(["person_id = ? AND (category = ? OR category = ?)", 5, 'Something', 'Else'])

Both calls delete the affected posts all at once with a single DELETE statement. If you need to destroy dependent associations or call your before_* or after_destroy callbacks, use the destroy_all method instead.

# File lib/active_record/base.rb, line 901
def delete_all(conditions = nil)
  sql = "DELETE FROM #{quoted_table_name} "
  add_conditions!(sql, conditions, scope(:find))
  connection.delete(sql, "#{name} Delete all")
end
descends_from_active_record?() click to toggle source

True if this isn't a concrete subclass needing a STI type condition.

# File lib/active_record/base.rb, line 1419
def descends_from_active_record?
  if superclass.abstract_class?
    superclass.descends_from_active_record?
  else
    superclass == Base || !columns_hash.include?(inheritance_column)
  end
end
destroy(id) click to toggle source

Destroy an object (or multiple objects) that has the given id, the object is instantiated first, therefore all callbacks and filters are fired off before the object is deleted. This method is less efficient than ActiveRecord#delete but allows cleanup methods and other actions to be run.

This essentially finds the object (or multiple objects) with the given id, creates a new object from the attributes, and then calls destroy on it.

Parameters

  • id - Can be either an Integer or an Array of Integers.

Examples

# Destroy a single object
Todo.destroy(1)

# Destroy multiple objects
todos = [1,2,3]
Todo.destroy(todos)
# File lib/active_record/base.rb, line 802
def destroy(id)
  if id.is_a?(Array)
    id.map { |one_id| destroy(one_id) }
  else
    find(id).destroy
  end
end
destroy_all(conditions = nil) click to toggle source

Destroys the records matching conditions by instantiating each record and calling its destroy method. Each object's callbacks are executed (including :dependent association options and before_destroy/after_destroy Observer methods). Returns the collection of objects that were destroyed; each will be frozen, to reflect that no changes should be made (since they can't be persisted).

Note: Instantiation, callback execution, and deletion of each record can be time consuming when you're removing many records at once. It generates at least one SQL DELETE query per record (or possibly more, to enforce your callbacks). If you want to delete many rows quickly, without concern for their associations or callbacks, use delete_all instead.

Parameters

  • conditions - A string, array, or hash that specifies which records to destroy. If omitted, all records are destroyed. See the Conditions section in the introduction to ActiveRecord::Base for more information.

Examples

Person.destroy_all("last_login < '2004-04-04'")
Person.destroy_all(:status => "inactive")
# File lib/active_record/base.rb, line 880
def destroy_all(conditions = nil)
  find(:all, :conditions => conditions).each { |object| object.destroy }
end
establish_connection(spec = nil) click to toggle source

Establishes the connection to the database. Accepts a hash as input where the :adapter key must be specified with the name of a database adapter (in lower-case) example for regular databases (MySQL, Postgresql, etc):

ActiveRecord::Base.establish_connection(
  :adapter  => "mysql",
  :host     => "localhost",
  :username => "myuser",
  :password => "mypass",
  :database => "somedatabase"
)

Example for SQLite database:

ActiveRecord::Base.establish_connection(
  :adapter => "sqlite",
  :database  => "path/to/dbfile"
)

Also accepts keys as strings (for parsing from YAML for example):

ActiveRecord::Base.establish_connection(
  "adapter" => "sqlite",
  "database"  => "path/to/dbfile"
)

The exceptions AdapterNotSpecified, AdapterNotFound and ArgumentError may be returned on an error.

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 51
def self.establish_connection(spec = nil)
  case spec
    when nil
      raise AdapterNotSpecified unless defined? RAILS_ENV
      establish_connection(RAILS_ENV)
    when ConnectionSpecification
      self.connection_handler.establish_connection(name, spec)
    when Symbol, String
      if configuration = configurations[spec.to_s]
        establish_connection(configuration)
      else
        raise AdapterNotSpecified, "#{spec} database is not configured"
      end
    else
      spec = spec.symbolize_keys
      unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end

      begin
        require 'rubygems'
        gem "activerecord-#{spec[:adapter]}-adapter"
        require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
      rescue LoadError
        begin
          require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
        rescue LoadError
          raise "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{$!})"
        end
      end

      adapter_method = "#{spec[:adapter]}_connection"
      if !respond_to?(adapter_method)
        raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter"
      end

      remove_connection
      establish_connection(ConnectionSpecification.new(spec, adapter_method))
  end
end
exists?(id_or_conditions = {}) click to toggle source

Returns true if a record exists in the table that matches the id or conditions given, or false otherwise. The argument can take five forms:

  • Integer - Finds the record with this primary key.

  • String - Finds the record with a primary key corresponding to this string (such as '5').

  • Array - Finds the record that matches these find-style conditions (such as ['color = ?', 'red']).

  • Hash - Finds the record that matches these find-style conditions (such as {:color => 'red'}).

  • No args - Returns false if the table is empty, true otherwise.

For more information about specifying conditions as a Hash or Array, see the Conditions section in the introduction to ActiveRecord::Base.

Note: You can't pass in a condition as a string (like name = 'Jamie'), since it would be sanitized and then queried against the primary key column, like id = 'name = \'Jamie\''.

Examples

Person.exists?(5)
Person.exists?('5')
Person.exists?(:name => "David")
Person.exists?(['name LIKE ?', "%#{query}%"])
Person.exists?
# File lib/active_record/base.rb, line 693
def exists?(id_or_conditions = {})
  find_initial(
    :select => "#{quoted_table_name}.#{primary_key}",
    :conditions => expand_id_conditions(id_or_conditions)) ? true : false
end
find(*args) click to toggle source

Find operates with four different retrieval approaches:

  • Find by id - This can either be a specific id (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]). If no record can be found for all of the listed ids, then RecordNotFound will be raised.

  • Find first - This will return the first record matched by the options used. These options can either be specific conditions or merely an order. If no record can be matched, nil is returned. Use Model.find(:first, *args) or its shortcut Model.first(*args).

  • Find last - This will return the last record matched by the options used. These options can either be specific conditions or merely an order. If no record can be matched, nil is returned. Use Model.find(:last, *args) or its shortcut Model.last(*args).

  • Find all - This will return all the records matched by the options used. If no records are found, an empty array is returned. Use Model.find(:all, *args) or its shortcut Model.all(*args).

All approaches accept an options hash as their last parameter.

Parameters

  • :conditions - An SQL fragment like "administrator = 1", [ "user_name = ?", username ], or ["user_name = :user_name", { :user_name => user_name }]. See conditions in the intro.

  • :order - An SQL fragment like "created_at DESC, name".

  • :group - An attribute name by which the result should be grouped. Uses the GROUP BY SQL-clause.

  • :having - Combined with :group this can be used to filter the records that a GROUP BY returns. Uses the HAVING SQL-clause.

  • :limit - An integer determining the limit on the number of rows that should be returned.

  • :offset - An integer determining the offset from where the rows should be fetched. So at 5, it would skip rows 0 through 4.

  • :joins - Either an SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id" (rarely needed), named associations in the same form used for the :include option, which will perform an INNER JOIN on the associated table(s), or an array containing a mixture of both strings and named associations. If the value is a string, then the records will be returned read-only since they will have attributes that do not correspond to the table's columns. Pass :readonly => false to override.

  • :include - Names associations that should be loaded alongside. The symbols named refer to already defined associations. See eager loading under Associations.

  • :select - By default, this is "*" as in "SELECT * FROM", but can be changed if you, for example, want to do a join but not include the joined columns. Takes a string with the SELECT SQL fragment (e.g. "id, name").

  • :from - By default, this is the table name of the class, but can be changed to an alternate table name (or even the name of a database view).

  • :readonly - Mark the returned records read-only so they cannot be saved or updated.

  • :lock - An SQL fragment like "FOR UPDATE" or "LOCK IN SHARE MODE". :lock => true gives connection's default exclusive lock, usually "FOR UPDATE".

Examples

# find by id
Person.find(1)       # returns the object for ID = 1
Person.find(1, 2, 6) # returns an array for objects with IDs in (1, 2, 6)
Person.find([7, 17]) # returns an array for objects with IDs in (7, 17)
Person.find([1])     # returns an array for the object with ID = 1
Person.find(1, :conditions => "administrator = 1", :order => "created_on DESC")

Note that returned records may not be in the same order as the ids you provide since database rows are unordered. Give an explicit :order to ensure the results are sorted.

Examples

# find first
Person.find(:first) # returns the first object fetched by SELECT * FROM people
Person.find(:first, :conditions => [ "user_name = ?", user_name])
Person.find(:first, :conditions => [ "user_name = :u", { :u => user_name }])
Person.find(:first, :order => "created_on DESC", :offset => 5)

# find last
Person.find(:last) # returns the last object fetched by SELECT * FROM people
Person.find(:last, :conditions => [ "user_name = ?", user_name])
Person.find(:last, :order => "created_on DESC", :offset => 5)

# find all
Person.find(:all) # returns an array of objects for all the rows fetched by SELECT * FROM people
Person.find(:all, :conditions => [ "category IN (?)", categories], :limit => 50)
Person.find(:all, :conditions => { :friends => ["Bob", "Steve", "Fred"] }
Person.find(:all, :offset => 10, :limit => 10)
Person.find(:all, :include => [ :account, :friends ])
Person.find(:all, :group => "category")

Example for find with a lock: Imagine two concurrent transactions: each will read person.visits == 2, add 1 to it, and save, resulting in two saves of person.visits = 3. By locking the row, the second transaction has to wait until the first is finished; we get the expected person.visits == 4.

Person.transaction do
  person = Person.find(1, :lock => true)
  person.visits += 1
  person.save!
end
# File lib/active_record/base.rb, line 611
def find(*args)
  options = args.extract_options!
  validate_find_options(options)
  set_readonly_option!(options)

  case args.first
    when :first then find_initial(options)
    when :last  then find_last(options)
    when :all   then find_every(options)
    else             find_from_ids(args, options)
  end
end
find_by_sql(sql) click to toggle source

Executes a custom SQL query against your database and returns all the results. The results will be returned as an array with columns requested encapsulated as attributes of the model you call this method from. If you call Product.find_by_sql then the results will be returned in a Product object with the attributes you specified in the SQL query.

If you call a complicated SQL query which spans multiple tables the columns specified by the SELECT will be attributes of the model, whether or not they are columns of the corresponding table.

The sql parameter is a full SQL query as a string. It will be called as is, there will be no database agnostic conversions performed. This should be a last resort because using, for example, MySQL specific terms will lock you to using that particular database engine or require you to change your call if you switch engines.

Examples

# A simple SQL query spanning multiple tables
Post.find_by_sql "SELECT p.title, c.author FROM posts p, comments c WHERE p.id = c.post_id"
> [#<Post:0x36bff9c @attributes={"title"=>"Ruby Meetup", "first_name"=>"Quentin"}>, ...]

# You can use the same string replacement techniques as you can with ActiveRecord#find
Post.find_by_sql ["SELECT title FROM posts WHERE author = ? AND created > ?", author_id, start_date]
> [#<Post:0x36bff9c @attributes={"first_name"=>"The Cheap Man Buys Twice"}>, ...]
# File lib/active_record/base.rb, line 664
def find_by_sql(sql)
  connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) }
end
first(*args) click to toggle source

A convenience wrapper for find(:first, *args). You can pass in all the same arguments to this method as you can to find(:first).

# File lib/active_record/base.rb, line 626
def first(*args)
  find(:first, *args)
end
human_attribute_name(attribute_key_name, options = {}) click to toggle source

Transforms attribute key names into a more humane format, such as "First name" instead of "first_name". Example:

Person.human_attribute_name("first_name") # => "First name"

This used to be depricated in favor of humanize, but is now preferred, because it automatically uses the I18n module now. Specify options with additional translating options.

# File lib/active_record/base.rb, line 1395
def human_attribute_name(attribute_key_name, options = {})
  defaults = self_and_descendants_from_active_record.map do |klass|
    :"#{klass.name.underscore}.#{attribute_key_name}"
  end
  defaults << options[:default] if options[:default]
  defaults.flatten!
  defaults << attribute_key_name.to_s.humanize
  options[:count] ||= 1
  I18n.translate(defaults.shift, options.merge(:default => defaults, :scope => [:activerecord, :attributes]))
end
human_name(options = {}) click to toggle source

Transform the modelname into a more humane format, using I18n. Defaults to the basic humanize method. Default scope of the translation is activerecord.models Specify options with additional translating options.

# File lib/active_record/base.rb, line 1410
def human_name(options = {})
  defaults = self_and_descendants_from_active_record.map do |klass|
    :"#{klass.name.underscore}"
  end 
  defaults << self.name.humanize
  I18n.translate(defaults.shift, {:scope => [:activerecord, :models], :count => 1, :default => defaults}.merge(options))
end
increment_counter(counter_name, id) click to toggle source

Increment a number field by one, usually representing a count.

This is used for caching aggregate values, so that they don't need to be computed every time. For example, a DiscussionBoard may cache post_count and comment_count otherwise every time the board is shown it would have to run an SQL query to find how many posts and comments there are.

Parameters

  • counter_name - The name of the field that should be incremented.

  • id - The id of the object that should be incremented.

Examples

# Increment the post_count column for the record with an id of 5
DiscussionBoard.increment_counter(:post_count, 5)
# File lib/active_record/base.rb, line 1007
def increment_counter(counter_name, id)
  update_counters(id, counter_name => 1)
end
inheritance_column() click to toggle source

Defines the column name for use with single table inheritance -- can be set in subclasses like so: self.inheritance_column = "type_id"

# File lib/active_record/base.rb, line 1215
def inheritance_column
  @inheritance_column ||= "type".freeze
end
inheritance_column=(value = nil, &block) click to toggle source
inspect() click to toggle source

Returns a string like 'Post id:integer, title:string, body:text'

# File lib/active_record/base.rb, line 1433
def inspect
  if self == Base
    super
  elsif abstract_class?
    "#{super}(abstract)"
  elsif table_exists?
    attr_list = columns.map { |c| "#{c.name}: #{c.type}" } * ', '
    "#{super}(#{attr_list})"
  else
    "#{super}(Table doesn't exist)"
  end
end
last(*args) click to toggle source

A convenience wrapper for find(:last, *args). You can pass in all the same arguments to this method as you can to find(:last).

# File lib/active_record/base.rb, line 632
def last(*args)
  find(:last, *args)
end
merge_conditions(*conditions) click to toggle source

Merges conditions so that the result is a valid condition

# File lib/active_record/base.rb, line 1523
def merge_conditions(*conditions)
  segments = []

  conditions.each do |condition|
    unless condition.blank?
      sql = sanitize_sql(condition)
      segments << sql unless sql.blank?
    end
  end

  "(#{segments.join(') AND (')})" unless segments.empty?
end
new(attributes = nil) click to toggle source

New objects can be instantiated as either empty (pass no construction parameter) or pre-set with attributes but not yet saved (pass a hash with key names matching the associated table column names). In both instances, valid attribute keys are determined by the column names of the associated table -- hence you can't have attributes that aren't part of the table columns.

# File lib/active_record/base.rb, line 2472
def initialize(attributes = nil)
  @attributes = attributes_from_column_definition
  @attributes_cache = {}
  @new_record = true
  ensure_proper_type
  self.attributes = attributes unless attributes.nil?
  assign_attributes(self.class.send(:scope, :create)) if self.class.send(:scoped?, :create)
  result = yield self if block_given?
  callback(:after_initialize) if respond_to_without_attributes?(:after_initialize)
  result
end
pluralize_table_names click to toggle source

Indicates whether table names should be the pluralized versions of the corresponding class names. If true, the default table name for a Product class will be products. If false, it would just be product. See table_name for the full rules on table/class naming. This is true, by default.

# File lib/active_record/base.rb, line 483
cattr_accessor :pluralize_table_names, :instance_writer => false
primary_key() click to toggle source

Defines the primary key field -- can be overridden in subclasses. Overwriting will negate any effect of the primary_key_prefix_type setting, though.

# File lib/active_record/base.rb, line 1188
def primary_key
  reset_primary_key
end
primary_key=(value = nil, &block) click to toggle source
Alias for: set_primary_key
primary_key_prefix_type click to toggle source

Accessor for the prefix type that will be prepended to every primary key column name. The options are :table_name and :table_name_with_underscore. If the first is specified, the Product class will look for "productid" instead of "id" as the primary column. If the latter is specified, the Product class will look for "product_id" instead of "id". Remember that this is a global setting for all Active Records.

# File lib/active_record/base.rb, line 457
cattr_accessor :primary_key_prefix_type, :instance_writer => false
readonly_attributes() click to toggle source

Returns an array of all the attributes that have been specified as readonly.

# File lib/active_record/base.rb, line 1100
def readonly_attributes
  read_inheritable_attribute(:attr_readonly)
end
remove_connection(klass = self) click to toggle source
# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 131
def remove_connection(klass = self)
  connection_handler.remove_connection(klass)
end
reset_column_information() click to toggle source

Resets all the cached information about columns, which will cause them to be reloaded on the next request.

The most common usage pattern for this method is probably in a migration, when just after creating a table you want to populate it with some default values, eg:

class CreateJobLevels < ActiveRecord::Migration
  def self.up
    create_table :job_levels do |t|
      t.integer :id
      t.string :name

      t.timestamps
    end

    JobLevel.reset_column_information
    %w{assistant executive manager director}.each do |type|
      JobLevel.create(:name => type)
    end
  end

  def self.down
    drop_table :job_levels
  end
end
# File lib/active_record/base.rb, line 1367
def reset_column_information
  generated_methods.each { |name| undef_method(name) }
  @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @generated_methods = @inheritance_column = nil
end
reset_counters(id, *counters) click to toggle source

Resets one or more counter caches to their correct value using an SQL count query. This is useful when adding new counter caches, or if the counter has been corrupted or modified directly by SQL.

Parameters

  • id - The id of the object you wish to reset a counter on.

  • counters - One or more counter names to reset

Examples

# For Post with id #1 records reset the comments_count
Post.reset_counters(1, :comments)
# File lib/active_record/base.rb, line 936
def reset_counters(id, *counters)
  object = find(id)
  counters.each do |association|
    child_class = reflect_on_association(association.to_sym).klass
    belongs_name = self.name.demodulize.underscore.to_sym
    counter_name = child_class.reflect_on_association(belongs_name).counter_cache_column
    value = object.send(association).count

    connection.update(            UPDATE #{quoted_table_name}            SET #{connection.quote_column_name(counter_name)} = #{value}            WHERE #{connection.quote_column_name(primary_key)} = #{quote_value(object.id)}, "#{name} UPDATE")
  end
  return true
end
respond_to?(method_id, include_private = false) click to toggle source
# File lib/active_record/base.rb, line 1508
def respond_to?(method_id, include_private = false)
  if match = DynamicFinderMatch.match(method_id)
    return true if all_attributes_exists?(match.attribute_names)
  elsif match = DynamicScopeMatch.match(method_id)
    return true if all_attributes_exists?(match.attribute_names)
  end

  super
end
retrieve_connection() click to toggle source
# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 122
def retrieve_connection
  connection_handler.retrieve_connection(self)
end
schema_format click to toggle source

Specifies the format to use when dumping the database schema with Rails' Rakefile. If :sql, the schema is dumped as (potentially database- specific) SQL statements. If :ruby, the schema is dumped as an ActiveRecord::Schema file which can be loaded into any database that supports migrations. Use :ruby if you want to have different database adapters for, e.g., your development and test environments.

# File lib/active_record/base.rb, line 509
cattr_accessor :schema_format , :instance_writer => false
sequence_name=(value = nil, &block) click to toggle source
Alias for: set_sequence_name
serialize(attr_name, class_name = Object) click to toggle source

If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object, then specify the name of that attribute using this method and it will be handled automatically. The serialization is done through YAML. If class_name is specified, the serialized object must be of that class on retrieval or SerializationTypeMismatch will be raised.

Parameters

  • attr_name - The field name that should be serialized.

  • class_name - Optional, class name that the object type should be equal to.

Example

# Serialize a preferences attribute
class User
  serialize :preferences
end
# File lib/active_record/base.rb, line 1119
def serialize(attr_name, class_name = Object)
  serialized_attributes[attr_name.to_s] = class_name
end
serialized_attributes() click to toggle source

Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.

# File lib/active_record/base.rb, line 1124
def serialized_attributes
  read_inheritable_attribute(:attr_serialized) or write_inheritable_attribute(:attr_serialized, {})
end
set_inheritance_column(value = nil, &block) click to toggle source

Sets the name of the inheritance column to use to the given value, or (if the value # is nil or false) to the value returned by the given block.

class Project < ActiveRecord::Base
  set_inheritance_column do
    original_inheritance_column + "_id"
  end
end
# File lib/active_record/base.rb, line 1263
def set_inheritance_column(value = nil, &block)
  define_attr_method :inheritance_column, value, &block
end
Also aliased as: inheritance_column=
set_primary_key(value = nil, &block) click to toggle source

Sets the name of the primary key column to use to the given value, or (if the value is nil or false) to the value returned by the given block.

class Project < ActiveRecord::Base
  set_primary_key "sysid"
end
# File lib/active_record/base.rb, line 1249
def set_primary_key(value = nil, &block)
  define_attr_method :primary_key, value, &block
end
Also aliased as: primary_key=
set_sequence_name(value = nil, &block) click to toggle source

Sets the name of the sequence to use when generating ids to the given value, or (if the value is nil or false) to the value returned by the given block. This is required for Oracle and is useful for any database which relies on sequences for primary key generation.

If a sequence name is not explicitly set when using Oracle or Firebird, it will default to the commonly used pattern of: #{table_name}_seq

If a sequence name is not explicitly set when using PostgreSQL, it will discover the sequence corresponding to your primary key for you.

class Project < ActiveRecord::Base
  set_sequence_name "projectseq"   # default would have been "project_seq"
end
# File lib/active_record/base.rb, line 1282
def set_sequence_name(value = nil, &block)
  define_attr_method :sequence_name, value, &block
end
Also aliased as: sequence_name=
set_table_name(value = nil, &block) click to toggle source

Sets the table name to use to the given value, or (if the value is nil or false) to the value returned by the given block.

class Project < ActiveRecord::Base
  set_table_name "project"
end
# File lib/active_record/base.rb, line 1237
def set_table_name(value = nil, &block)
  define_attr_method :table_name, value, &block
end
Also aliased as: table_name=
silence() click to toggle source

Silences the logger for the duration of the block.

# File lib/active_record/base.rb, line 1480
def silence
  old_logger_level, logger.level = logger.level, Logger::ERROR if logger
  yield
ensure
  logger.level = old_logger_level if logger
end
sti_name() click to toggle source
# File lib/active_record/base.rb, line 1518
def sti_name
  store_full_sti_class ? name : name.demodulize
end
table_exists?() click to toggle source

Indicates whether the table associated with this class exists

# File lib/active_record/base.rb, line 1298
def table_exists?
  connection.table_exists?(table_name)
end
table_name() click to toggle source

Guesses the table name (in forced lower-case) based on the name of the class in the inheritance hierarchy descending directly from ActiveRecord::Base. So if the hierarchy looks like: Reply < Message < ActiveRecord::Base, then Message is used to guess the table name even when called on Reply. The rules used to do the guess are handled by the Inflector class in Active Support, which knows almost all common English inflections. You can add new inflections in config/initializers/inflections.rb.

Nested classes are given table names prefixed by the singular form of the parent's table name. Enclosing modules are not considered.

Examples

class Invoice < ActiveRecord::Base; end;
file                  class               table_name
invoice.rb            Invoice             invoices

class Invoice < ActiveRecord::Base; class Lineitem < ActiveRecord::Base; end; end;
file                  class               table_name
invoice.rb            Invoice::Lineitem   invoice_lineitems

module Invoice; class Lineitem < ActiveRecord::Base; end; end;
file                  class               table_name
invoice/lineitem.rb   Invoice::Lineitem   lineitems

Additionally, the class-level table_name_prefix is prepended and the table_name_suffix is appended. So if you have "myapp_" as a prefix, the table name guess for an Invoice class becomes "myapp_invoices". Invoice::Lineitem becomes "myapp_invoice_lineitems".

You can also overwrite this class method to allow for unguessable links, such as a Mouse class with a link to a "mice" table. Example:

class Mouse < ActiveRecord::Base
  set_table_name "mice"
end
# File lib/active_record/base.rb, line 1161
def table_name
  reset_table_name
end
table_name=(value = nil, &block) click to toggle source
Alias for: set_table_name
table_name_prefix click to toggle source

Accessor for the name of the prefix string to prepend to every table name. So if set to "basecamp_", all table names will be named like "basecamp_projects", "basecamp_people", etc. This is a convenient way of creating a namespace for tables in a shared database. By default, the prefix is the empty string.

If you are organising your models within modules you can add a prefix to the models within a namespace by defining a singleton method in the parent module called table_name_prefix which returns your chosen prefix.

# File lib/active_record/base.rb, line 468
cattr_accessor :table_name_prefix, :instance_writer => false
table_name_suffix click to toggle source

Works like table_name_prefix, but appends instead of prepends (set to "_basecamp" gives "projects_basecamp", "people_basecamp"). By default, the suffix is the empty string.

# File lib/active_record/base.rb, line 475
cattr_accessor :table_name_suffix, :instance_writer => false
timestamped_migrations click to toggle source

Specify whether or not to use timestamps for migration numbers

# File lib/active_record/base.rb, line 515
cattr_accessor :timestamped_migrations , :instance_writer => false
update(id, attributes) click to toggle source

Updates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.

Parameters

  • id - This should be the id or an array of ids to be updated.

  • attributes - This should be a hash of attributes to be set on the object, or an array of hashes.

Examples

# Updating one record:
Person.update(15, :user_name => 'Samuel', :group => 'expert')

# Updating multiple records:
people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } }
Person.update(people.keys, people.values)
# File lib/active_record/base.rb, line 748
def update(id, attributes)
  if id.is_a?(Array)
    idx = -1
    id.collect { |one_id| idx += 1; update(one_id, attributes[idx]) }
  else
    object = find(id)
    object.update_attributes(attributes)
    object
  end
end
update_all(updates, conditions = nil, options = {}) click to toggle source

Updates all records with details given if they match a set of conditions supplied, limits and order can also be supplied. This method constructs a single SQL UPDATE statement and sends it straight to the database. It does not instantiate the involved models and it does not trigger Active Record callbacks.

Parameters

  • updates - A string of column and value pairs that will be set on any records that match conditions. This creates the SET clause of the generated SQL.

  • conditions - An SQL fragment like "administrator = 1" or [ "user_name = ?", username ]. See conditions in the intro for more info.

  • options - Additional options are :limit and :order, see the examples for usage.

Examples

# Update all billing objects with the 3 different attributes given
Billing.update_all( "category = 'authorized', approved = 1, author = 'David'" )

# Update records that match our conditions
Billing.update_all( "author = 'David'", "title LIKE '%Rails%'" )

# Update records that match our conditions but limit it to 5 ordered by date
Billing.update_all( "author = 'David'", "title LIKE '%Rails%'",
                      :order => 'created_at', :limit => 5 )
# File lib/active_record/base.rb, line 831
def update_all(updates, conditions = nil, options = {})
  sql  = "UPDATE #{quoted_table_name} SET #{sanitize_sql_for_assignment(updates)} "

  scope = scope(:find)

  select_sql = ""
  add_conditions!(select_sql, conditions, scope)

  if options.has_key?(:limit) || (scope && scope[:limit])
    # Only take order from scope if limit is also provided by scope, this
    # is useful for updating a has_many association with a limit.
    add_order!(select_sql, options[:order], scope)

    add_limit!(select_sql, options, scope)
    sql.concat(connection.limited_update_conditions(select_sql, quoted_table_name, connection.quote_column_name(primary_key)))
  else
    add_order!(select_sql, options[:order], nil)
    sql.concat(select_sql)
  end

  connection.update(sql, "#{name} Update")
end
update_counters(id, counters) click to toggle source

A generic "counter updater" implementation, intended primarily to be used by increment_counter and decrement_counter, but which may also be useful on its own. It simply does a direct SQL update for the record with the given ID, altering the given hash of counters by the amount given by the corresponding value:

Parameters

  • id - The id of the object you wish to update a counter on or an Array of ids.

  • counters - An Array of Hashes containing the names of the fields to update as keys and the amount to update the field by as values.

Examples

# For the Post with id of 5, decrement the comment_count by 1, and
# increment the action_count by 1
Post.update_counters 5, :comment_count => -1, :action_count => 1
# Executes the following SQL:
# UPDATE posts
#    SET comment_count = comment_count - 1,
#        action_count = action_count + 1
#  WHERE id = 5

# For the Posts with id of 10 and 15, increment the comment_count by 1
Post.update_counters [10, 15], :comment_count => 1
# Executes the following SQL:
# UPDATE posts
#    SET comment_count = comment_count + 1,
#  WHERE id IN (10, 15)
# File lib/active_record/base.rb, line 982
def update_counters(id, counters)
  updates = counters.map do |counter_name, value|
    operator = value < 0 ? '-' : '+'
    quoted_column = connection.quote_column_name(counter_name)
    "#{quoted_column} = COALESCE(#{quoted_column}, 0) #{operator} #{value.abs}"
  end

  update_all(updates.join(', '), primary_key => id )
end
verification_timeout() click to toggle source

Deprecated and no longer has any effect.

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 102
def verification_timeout
  ActiveSupport::Deprecation.warn("ActiveRecord::Base.verification_timeout has been deprecated and no longer has any effect. Please remove all references to verification_timeout.")
end
verification_timeout=(flag) click to toggle source

Deprecated and no longer has any effect.

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 107
def verification_timeout=(flag)
  ActiveSupport::Deprecation.warn("ActiveRecord::Base.verification_timeout= has been deprecated and no longer has any effect. Please remove all references to verification_timeout=.")
end

Protected Class Methods

aggregate_mapping(reflection) click to toggle source
# File lib/active_record/base.rb, line 2287
def aggregate_mapping(reflection)
  mapping = reflection.options[:mapping] || [reflection.name, reflection.name]
  mapping.first.is_a?(Array) ? mapping : [mapping]
end
class_of_active_record_descendant(klass) click to toggle source

Returns the class descending directly from ActiveRecord::Base or an abstract class, if any, in the inheritance hierarchy.

# File lib/active_record/base.rb, line 2245
def class_of_active_record_descendant(klass)
  if klass.superclass == Base || klass.superclass.abstract_class?
    klass
  elsif klass.superclass.nil?
    raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord"
  else
    class_of_active_record_descendant(klass.superclass)
  end
end
compute_type(type_name) click to toggle source

Returns the class type of the record using the current module as a prefix. So descendants of MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.

# File lib/active_record/base.rb, line 2232
def compute_type(type_name)
  modularized_name = type_name_with_module(type_name)
  silence_warnings do
    begin
      class_eval(modularized_name, __FILE__)
    rescue NameError
      class_eval(type_name, __FILE__)
    end
  end
end
default_scope(options = {}) click to toggle source

Sets the default options for the model. The format of the options argument is the same as in find.

class Person < ActiveRecord::Base
  default_scope :order => 'last_name, first_name'
end
# File lib/active_record/base.rb, line 2204
def default_scope(options = {})
  self.default_scoping << { :find => options, :create => options[:conditions].is_a?(Hash) ? options[:conditions] : {} }
end
expand_hash_conditions_for_aggregates(attrs) click to toggle source

Accepts a hash of SQL conditions and replaces those attributes that correspond to a composed_of relationship with their expanded aggregate attribute values. Given:

class Person < ActiveRecord::Base
  composed_of :address, :class_name => "Address",
    :mapping => [%w(address_street street), %w(address_city city)]
end

Then:

{ :address => Address.new("813 abc st.", "chicago") }
  # => { :address_street => "813 abc st.", :address_city => "chicago" }
# File lib/active_record/base.rb, line 2303
def expand_hash_conditions_for_aggregates(attrs)
  expanded_attrs = {}
  attrs.each do |attr, value|
    unless (aggregation = reflect_on_aggregation(attr.to_sym)).nil?
      mapping = aggregate_mapping(aggregation)
      mapping.each do |field_attr, aggregate_attr|
        if mapping.size == 1 && !value.respond_to?(aggregate_attr)
          expanded_attrs[field_attr] = value
        else
          expanded_attrs[field_attr] = value.send(aggregate_attr)
        end
      end
    else
      expanded_attrs[attr] = value
    end
  end
  expanded_attrs
end
sanitize_conditions(condition, table_name = quoted_table_name) click to toggle source
Alias for: sanitize_sql
sanitize_sql(condition, table_name = quoted_table_name) click to toggle source
Also aliased as: sanitize_conditions
sanitize_sql_array(ary) click to toggle source

Accepts an array of conditions. The array has each value sanitized and interpolated into the SQL statement.

["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
# File lib/active_record/base.rb, line 2375
def sanitize_sql_array(ary)
  statement, *values = ary
  if values.first.is_a?(Hash) and statement =~ /:\w+/
    replace_named_bind_variables(statement, values.first)
  elsif statement.include?('?')
    replace_bind_variables(statement, values)
  else
    statement % values.collect { |value| connection.quote_string(value.to_s) }
  end
end
sanitize_sql_for_assignment(assignments) click to toggle source

Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a SET clause.

{ :name => nil, :group_id => 4 }  returns "name = NULL , group_id='4'"
# File lib/active_record/base.rb, line 2279
def sanitize_sql_for_assignment(assignments)
  case assignments
    when Array; sanitize_sql_array(assignments)
    when Hash;  sanitize_sql_hash_for_assignment(assignments)
    else        assignments
  end
end
sanitize_sql_for_conditions(condition, table_name = quoted_table_name) click to toggle source

Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a WHERE clause.

["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
{ :name => "foo'bar", :group_id => 4 }  returns "name='foo''bar' and group_id='4'"
"name='foo''bar' and group_id='4'" returns "name='foo''bar' and group_id='4'"
# File lib/active_record/base.rb, line 2265
def sanitize_sql_for_conditions(condition, table_name = quoted_table_name)
  return nil if condition.blank?

  case condition
    when Array; sanitize_sql_array(condition)
    when Hash;  sanitize_sql_hash_for_conditions(condition, table_name)
    else        condition
  end
end
Also aliased as: sanitize_sql
sanitize_sql_hash(attrs, default_table_name = quoted_table_name) click to toggle source
sanitize_sql_hash_for_assignment(attrs) click to toggle source

Sanitizes a hash of attribute/value pairs into SQL conditions for a SET clause.

{ :status => nil, :group_id => 1 }
  # => "status = NULL , group_id = 1"
# File lib/active_record/base.rb, line 2366
def sanitize_sql_hash_for_assignment(attrs)
  attrs.map do |attr, value|
    "#{connection.quote_column_name(attr)} = #{quote_bound_value(value)}"
  end.join(', ')
end
sanitize_sql_hash_for_conditions(attrs, default_table_name = quoted_table_name) click to toggle source

Sanitizes a hash of attribute/value pairs into SQL conditions for a WHERE clause.

{ :name => "foo'bar", :group_id => 4 }
  # => "name='foo''bar' and group_id= 4"
{ :status => nil, :group_id => [1,2,3] }
  # => "status IS NULL and group_id IN (1,2,3)"
{ :age => 13..18 }
  # => "age BETWEEN 13 AND 18"
{ 'other_records.id' => 7 }
  # => "`other_records`.`id` = 7"
{ :other_records => { :id => 7 } }
  # => "`other_records`.`id` = 7"

And for value objects on a composed_of relationship:

{ :address => Address.new("123 abc st.", "chicago") }
  # => "address_street='123 abc st.' and address_city='chicago'"
# File lib/active_record/base.rb, line 2336
def sanitize_sql_hash_for_conditions(attrs, default_table_name = quoted_table_name)
  attrs = expand_hash_conditions_for_aggregates(attrs)

  conditions = attrs.map do |attr, value|
    table_name = default_table_name

    unless value.is_a?(Hash)
      attr = attr.to_s

      # Extract table name from qualified attribute names.
      if attr.include?('.')
        attr_table_name, attr = attr.split('.', 2)
        attr_table_name = connection.quote_table_name(attr_table_name)
      else
        attr_table_name = table_name
      end

      attribute_condition("#{attr_table_name}.#{connection.quote_column_name(attr)}", value)
    else
      sanitize_sql_hash_for_conditions(value, connection.quote_table_name(attr.to_s))
    end
  end.join(' AND ')

  replace_bind_variables(conditions, expand_range_bind_variables(attrs.values))
end
Also aliased as: sanitize_sql_hash
with_exclusive_scope(method_scoping = {}, &block) click to toggle source

Works like with_scope, but discards any nested properties.

# File lib/active_record/base.rb, line 2189
def with_exclusive_scope(method_scoping = {}, &block)
  with_scope(method_scoping, :overwrite, &block)
end
with_scope(method_scoping = {}, action = :merge, &block) click to toggle source

Scope parameters to method calls within the block. Takes a hash of method_name => parameters hash. method_name may be :find or :create. :find parameters may include the :conditions, :joins, :include, :offset, :limit, and :readonly options. :create parameters are an attributes hash.

class Article < ActiveRecord::Base
  def self.create_with_scope
    with_scope(:find => { :conditions => "blog_id = 1" }, :create => { :blog_id => 1 }) do
      find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1
      a = create(1)
      a.blog_id # => 1
    end
  end
end

In nested scopings, all previous parameters are overwritten by the innermost rule, with the exception of :conditions, :include, and :joins options in :find, which are merged.

:joins options are uniqued so multiple scopes can join in the same table without table aliasing problems. If you need to join multiple tables, but still want one of the tables to be uniqued, use the array of strings format for your joins.

class Article < ActiveRecord::Base
  def self.find_with_scope
    with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }, :create => { :blog_id => 1 }) do
      with_scope(:find => { :limit => 10 })
        find(:all) # => SELECT * from articles WHERE blog_id = 1 LIMIT 10
      end
      with_scope(:find => { :conditions => "author_id = 3" })
        find(:all) # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1
      end
    end
  end
end

You can ignore any previous scopings by using the with_exclusive_scope method.

class Article < ActiveRecord::Base
  def self.find_with_exclusive_scope
    with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }) do
      with_exclusive_scope(:find => { :limit => 10 })
        find(:all) # => SELECT * from articles LIMIT 10
      end
    end
  end
end

Note: the :find scope also has effect on update and deletion methods, like update_all and delete_all.

# File lib/active_record/base.rb, line 2128
def with_scope(method_scoping = {}, action = :merge, &block)
  method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping)

  # Dup first and second level of hash (method and params).
  method_scoping = method_scoping.inject({}) do |hash, (method, params)|
    hash[method] = (params == true) ? params : params.dup
    hash
  end

  method_scoping.assert_valid_keys([ :find, :create ])

  if f = method_scoping[:find]
    f.assert_valid_keys(VALID_FIND_OPTIONS)
    set_readonly_option! f
  end

  # Merge scopings
  if [:merge, :reverse_merge].include?(action) && current_scoped_methods
    method_scoping = current_scoped_methods.inject(method_scoping) do |hash, (method, params)|
      case hash[method]
        when Hash
          if method == :find
            (hash[method].keys + params.keys).uniq.each do |key|
              merge = hash[method][key] && params[key] # merge if both scopes have the same key
              if key == :conditions && merge
                if params[key].is_a?(Hash) && hash[method][key].is_a?(Hash)
                  hash[method][key] = merge_conditions(hash[method][key].deep_merge(params[key]))
                else
                  hash[method][key] = merge_conditions(params[key], hash[method][key])
                end
              elsif key == :include && merge
                hash[method][key] = merge_includes(hash[method][key], params[key]).uniq
              elsif key == :joins && merge
                hash[method][key] = merge_joins(params[key], hash[method][key])
              else
                hash[method][key] = hash[method][key] || params[key]
              end
            end
          else
            if action == :reverse_merge
              hash[method] = hash[method].merge(params)
            else
              hash[method] = params.merge(hash[method])
            end
          end
        else
          hash[method] = params
      end
      hash
    end
  end

  self.scoped_methods << method_scoping
  begin
    yield
  ensure
    self.scoped_methods.pop
  end
end

Public Instance Methods

==(comparison_object) click to toggle source

Returns true if the comparison_object is the same object, or is of the same type and has the same id.

# File lib/active_record/base.rb, line 2853
def ==(comparison_object)
  comparison_object.equal?(self) ||
    (comparison_object.instance_of?(self.class) &&
      comparison_object.id == id &&
      !comparison_object.new_record?)
end
[](attr_name) click to toggle source

Returns the value of the attribute identified by attr_name after it has been typecast (for example, "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)). (Alias for the protected read_attribute method).

# File lib/active_record/base.rb, line 2751
def [](attr_name)
  read_attribute(attr_name)
end
[]=(attr_name, value) click to toggle source

Updates the attribute identified by attr_name with the specified value. (Alias for the protected write_attribute method).

# File lib/active_record/base.rb, line 2757
def []=(attr_name, value)
  write_attribute(attr_name, value)
end
attribute_for_inspect(attr_name) click to toggle source

Returns an #inspect-like string for the value of the attribute attr_name. String attributes are elided after 50 characters, and Date and Time attributes are returned in the :db format. Other attributes return the value of #inspect without modification.

person = Person.create!(:name => "David Heinemeier Hansson " * 3)

person.attribute_for_inspect(:name)
# => '"David Heinemeier Hansson David Heinemeier Hansson D..."'

person.attribute_for_inspect(:created_at)
# => '"2009-01-12 04:48:57"'
# File lib/active_record/base.rb, line 2818
def attribute_for_inspect(attr_name)
  value = read_attribute(attr_name)

  if value.is_a?(String) && value.length > 50
    "#{value[0..50]}...".inspect
  elsif value.is_a?(Date) || value.is_a?(Time)
    %("#{value.to_s(:db)}")
  else
    value.inspect
  end
end
attribute_names() click to toggle source

Returns an array of names for the attributes available on this object sorted alphabetically.

# File lib/active_record/base.rb, line 2843
def attribute_names
  @attributes.keys.sort
end
attribute_present?(attribute) click to toggle source

Returns true if the specified attribute has been set by the user or by a database load and is neither nil nor empty? (the latter only applies to objects that respond to empty?, most notably Strings).

# File lib/active_record/base.rb, line 2832
def attribute_present?(attribute)
  value = read_attribute(attribute)
  !value.blank?
end
attributes() click to toggle source

Returns a hash of all the attributes with their names as keys and the values of the attributes as values.

# File lib/active_record/base.rb, line 2791
def attributes
  attrs = {}
  attribute_names.each { |name| attrs[name] = read_attribute(name) }
  attrs
end
attributes=(new_attributes, guard_protected_attributes = true) click to toggle source

Allows you to set all the attributes at once by passing in a hash with keys matching the attribute names (which again matches the column names).

If guard_protected_attributes is true (the default), then sensitive attributes can be protected from this form of mass-assignment by using the attr_protected macro. Or you can alternatively specify which attributes can be accessed with the attr_accessible macro. Then all the attributes not included in that won't be allowed to be mass-assigned.

class User < ActiveRecord::Base
  attr_protected :is_admin
end

user = User.new
user.attributes = { :username => 'Phusion', :is_admin => true }
user.username   # => "Phusion"
user.is_admin?  # => false

user.send(:attributes=, { :username => 'Phusion', :is_admin => true }, false)
user.is_admin?  # => true
# File lib/active_record/base.rb, line 2781
def attributes=(new_attributes, guard_protected_attributes = true)
  return if new_attributes.nil?
  attributes = new_attributes.dup
  attributes.stringify_keys!

  attributes = remove_attributes_protected_from_mass_assignment(attributes) if guard_protected_attributes
  assign_attributes(attributes) if attributes and attributes.any?
end
attributes_before_type_cast() click to toggle source

Returns a hash of attributes before typecasting and deserialization.

# File lib/active_record/base.rb, line 2798
def attributes_before_type_cast
  self.attribute_names.inject({}) do |attrs, name|
    attrs[name] = read_attribute_before_type_cast(name)
    attrs
  end
end
becomes(klass) click to toggle source

Returns an instance of the specified klass with the attributes of the current record. This is mostly useful in relation to single-table inheritance structures where you want a subclass to appear as the superclass. This can be used along with record identification in Action Pack to allow, say, Client < Company to do something like render :partial => @client.becomes(Company) to render that instance using the companies/company partial instead of clients/client.

Note: The new instance will share a link to the same attributes as the original class. So any change to the attributes in either instance will affect the other.

# File lib/active_record/base.rb, line 2648
def becomes(klass)
  klass.new.tap do |became|
    became.instance_variable_set("@attributes", @attributes)
    became.instance_variable_set("@attributes_cache", @attributes_cache)
    became.instance_variable_set("@new_record", new_record?)
  end
end
cache_key() click to toggle source

Returns a cache key that can be used to identify this record.

Examples

Product.new.cache_key     # => "products/new"
Product.find(5).cache_key # => "products/5" (updated_at not available)
Person.find(5).cache_key  # => "people/5-20071224150000" (updated_at available)
# File lib/active_record/base.rb, line 2530
def cache_key
  case
  when new_record?
    "#{self.class.model_name.cache_key}/new"
  when timestamp = self[:updated_at]
    "#{self.class.model_name.cache_key}/#{id}-#{timestamp.to_s(:number)}"
  else
    "#{self.class.model_name.cache_key}/#{id}"
  end
end
clone() click to toggle source

Returns a clone of the record that hasn't been assigned an id yet and is treated as a new record. Note that this is a "shallow" clone: it copies the object's attributes only, not its associations. The extent of a "deep" clone is application-specific and is therefore left to the application to implement according to its need.

# File lib/active_record/base.rb, line 2633
def clone
  attrs = clone_attributes(:read_attribute_before_type_cast)
  attrs.delete(self.class.primary_key)
  record = self.class.new
  record.send :instance_variable_set, '@attributes', attrs
  record
end
column_for_attribute(name) click to toggle source

Returns the column object for the named attribute.

# File lib/active_record/base.rb, line 2848
def column_for_attribute(name)
  self.class.columns_hash[name.to_s]
end
connection() click to toggle source

Returns the connection currently associated with the class. This can also be used to "borrow" the connection to do database work that isn't easily done without going straight to SQL.

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 19
def connection
  self.class.connection
end
decrement(attribute, by = 1) click to toggle source

Initializes attribute to zero if nil and subtracts the value passed as by (default is 1). The decrement is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.

# File lib/active_record/base.rb, line 2705
def decrement(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] -= by
  self
end
decrement!(attribute, by = 1) click to toggle source

Wrapper around decrement that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.

# File lib/active_record/base.rb, line 2715
def decrement!(attribute, by = 1)
  decrement(attribute, by).update_attribute(attribute, self[attribute])
end
delete() click to toggle source

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can't be persisted). Returns the frozen instance.

The row is simply removed with a SQL DELETE statement on the record's primary key, and no callbacks are executed.

To enforce the object's before_destroy and after_destroy callbacks, Observer methods, or any :dependent association options, use #destroy.

# File lib/active_record/base.rb, line 2607
def delete
  self.class.delete(id) unless new_record?
  @destroyed = true
  freeze
end
destroy() click to toggle source

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can't be persisted).

# File lib/active_record/base.rb, line 2615
def destroy
  unless new_record?
    connection.delete(
      "DELETE FROM #{self.class.quoted_table_name} " +
      "WHERE #{connection.quote_column_name(self.class.primary_key)} = #{quoted_id}",
      "#{self.class.name} Destroy"
    )
  end

  @destroyed = true
  freeze
end
destroyed?() click to toggle source

Returns true if the record has been destroyed.

# File lib/active_record/base.rb, line 2882
def destroyed?
  @destroyed
end
eql?(comparison_object) click to toggle source

Delegates to ==

# File lib/active_record/base.rb, line 2861
def eql?(comparison_object)
  self == (comparison_object)
end
freeze() click to toggle source

Freeze the attributes hash such that associations are still accessible, even on destroyed records.

# File lib/active_record/base.rb, line 2872
def freeze
  @attributes.freeze; self
end
frozen?() click to toggle source

Returns true if the attributes hash has been frozen.

# File lib/active_record/base.rb, line 2877
def frozen?
  @attributes.frozen?
end
has_attribute?(attr_name) click to toggle source

Returns true if the given attribute is in the attributes hash

# File lib/active_record/base.rb, line 2838
def has_attribute?(attr_name)
  @attributes.has_key?(attr_name.to_s)
end
hash() click to toggle source

Delegates to id in order to allow two records of the same type and id to work with something like:

[ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
# File lib/active_record/base.rb, line 2867
def hash
  id.hash
end
id() click to toggle source

A model instance's primary key is always available as model.id whether you name it the default 'id' or set it to something else.

# File lib/active_record/base.rb, line 2486
def id
  attr_name = self.class.primary_key
  column = column_for_attribute(attr_name)

  self.class.send(:define_read_method, :id, attr_name, column)
  # now that the method exists, call it
  self.send attr_name.to_sym

end
id=(value) click to toggle source

Sets the primary ID.

# File lib/active_record/base.rb, line 2550
def id=(value)
  write_attribute(self.class.primary_key, value)
end
increment(attribute, by = 1) click to toggle source

Initializes attribute to zero if nil and adds the value passed as by (default is 1). The increment is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.

# File lib/active_record/base.rb, line 2688
def increment(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] += by
  self
end
increment!(attribute, by = 1) click to toggle source

Wrapper around increment that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.

# File lib/active_record/base.rb, line 2698
def increment!(attribute, by = 1)
  increment(attribute, by).update_attribute(attribute, self[attribute])
end
inspect() click to toggle source

Returns the contents of the record as a nicely formatted string.

# File lib/active_record/base.rb, line 2898
def inspect
  attributes_as_nice_string = self.class.column_names.collect { |name|
    if has_attribute?(name) || new_record?
      "#{name}: #{attribute_for_inspect(name)}"
    end
  }.compact.join(", ")
  "#<#{self.class} #{attributes_as_nice_string}>"
end
new_record?() click to toggle source

Returns true if this object hasn't been saved yet -- that is, a record for the object doesn't exist yet; otherwise, returns false.

# File lib/active_record/base.rb, line 2555
def new_record?
  @new_record || false
end
readonly!() click to toggle source

Marks this record as read only.

# File lib/active_record/base.rb, line 2893
def readonly!
  @readonly = true
end
readonly?() click to toggle source

Returns true if the record is read only. Records loaded through joins with piggy-back attributes will be marked as read only since they cannot be saved.

# File lib/active_record/base.rb, line 2888
def readonly?
  defined?(@readonly) && @readonly == true
end
reload(options = nil) click to toggle source

Reloads the attributes of this object from the database. The optional options argument is passed to find when reloading so you may do e.g. record.reload(:lock => true) to reload the same record with an exclusive row lock.

# File lib/active_record/base.rb, line 2740
def reload(options = nil)
  clear_aggregation_cache
  clear_association_cache
  @attributes.update(self.class.send(:with_exclusive_scope) { self.class.find(self.id, options) }.instance_variable_get('@attributes'))
  @attributes_cache = {}
  self
end
save(perform_validation = true) click to toggle source

Saves the model.

If the model is new a record gets created in the database, otherwise the existing record gets updated.

If perform_validation is true validations run. If any of them fail the action is cancelled and save returns false. If the flag is false validations are bypassed altogether. See ActiveRecord::Validations for more information.

There's a series of callbacks associated with save. If any of the before_* callbacks return false the action is cancelled and save returns false. See ActiveRecord::Callbacks for further details.

# File lib/active_record/base.rb, line 2576
def save
  create_or_update
end
save!() click to toggle source

Saves the model.

If the model is new a record gets created in the database, otherwise the existing record gets updated.

With save! validations always run. If any of them fail ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations for more information.

There's a series of callbacks associated with save!. If any of the before_* callbacks return false the action is cancelled and save! raises ActiveRecord::RecordNotSaved. See ActiveRecord::Callbacks for further details.

# File lib/active_record/base.rb, line 2593
def save!
  create_or_update || raise(RecordNotSaved)
end
to_param() click to toggle source

Returns a String, which Action Pack uses for constructing an URL to this object. The default implementation returns this record's id as a String, or nil if this record's unsaved.

For example, suppose that you have a User model, and that you have a map.resources :users route. Normally, user_path will construct a path with the user object's 'id' in it:

user = User.find_by_name('Phusion')
user_path(user)  # => "/users/1"

You can override to_param in your model to make user_path construct a path using the user's name instead of the user's id:

class User < ActiveRecord::Base
  def to_param  # overridden
    name
  end
end

user = User.find_by_name('Phusion')
user_path(user)  # => "/users/Phusion"
# File lib/active_record/base.rb, line 2518
def to_param
  # We can't use alias_method here, because method 'id' optimizes itself on the fly.
  (id = self.id) ? id.to_s : nil # Be sure to stringify the id for routes
end
toggle(attribute) click to toggle source

Assigns to attribute the boolean opposite of attribute?. So if the predicate returns true the attribute will become false. This method toggles directly the underlying value without calling any setter. Returns self.

# File lib/active_record/base.rb, line 2723
def toggle(attribute)
  self[attribute] = !send("#{attribute}?")
  self
end
toggle!(attribute) click to toggle source

Wrapper around toggle that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.

# File lib/active_record/base.rb, line 2732
def toggle!(attribute)
  toggle(attribute).update_attribute(attribute, self[attribute])
end
update_attribute(name, value) click to toggle source

Updates a single attribute and saves the record without going through the normal validation procedure. This is especially useful for boolean flags on existing records. The regular update_attribute method in Base is replaced with this when the validations module is mixed in, which it is by default.

# File lib/active_record/base.rb, line 2659
def update_attribute(name, value)
  send(name.to_s + '=', value)
  save(false)
end
update_attributes(attributes) click to toggle source

Updates all the attributes from the passed-in Hash and saves the record. If the object is invalid, the saving will fail and false will be returned.

# File lib/active_record/base.rb, line 2666
def update_attributes(attributes)
  with_transaction_returning_status(:update_attributes_inside_transaction, attributes)
end
update_attributes!(attributes) click to toggle source

Updates an object just like Base.update_attributes but calls save! instead of save so an exception is raised if the record is invalid.

# File lib/active_record/base.rb, line 2676
def update_attributes!(attributes)
  with_transaction_returning_status(:update_attributes_inside_transaction!, attributes)
end

[Validate]

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