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ActiveRecord::Base

Active Record

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/activerecord/README_rdoc.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)
    where("user_name = '#{user_name}' AND password = '#{password}'").first
  end

  def self.authenticate_safely(user_name, password)
    where("user_name = ? AND password = ?", user_name, password).first
  end

  def self.authenticate_safely_simply(user_name, password)
    where(:user_name => user_name, :password => password).first
  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.where(
  "id = :id AND name = :name AND division = :division AND created_at > :accounting_date",
  { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' }
).first

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

Student.where(:first_name => "Harvey", :status => 1)
Student.where(params[:student])

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

Student.where(:grade => 9..12)

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

Student.where(:grade => [9,11,12])

When joining tables, nested hashes or keys written in the form ‘table_name.column_name’ can be used to qualify the table name of a particular condition. For instance:

Student.joins(:schools).where(:schools => { :type => 'public' })
Student.joins(:schools).where('schools.type' => 'public' )

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.

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).

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_ and thus produces finders like Person.find_by_user_name, Person.find_all_by_last_name, and Payment.find_by_transaction_id. Instead of writing Person.where(:user_name => user_name).first, you just do Person.find_by_user_name(user_name). And instead of writing Person.where(:last_name => last_name).all, 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”.

Person.where(:user_name => user_name, :password => password).first
Person.find_by_user_name_and_password #with dynamic finder

Person.where(:user_name => user_name, :password => password, :gender => 'male').first
Payment.find_by_user_name_and_password_and_gender

It’s even possible to call these dynamic finder methods on relations and named scopes.

Payment.order("created_on").find_all_by_amount(50)
Payment.pending.find_last_by_amount(100)

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.

# 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.

# 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.

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.

Just like find_by_*, you can also use scoped_by_* to retrieve data. The good thing about using this feature is that the very first time result is returned using method_missing technique but after that the method is declared on the class. Henceforth method_missing will not be hit.

User.scoped_by_user_name('David')

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.

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.

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.where(:name => '37signals').first 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.

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 813
def ===(object)
  object.is_a?(self)
end
abstract_class?() click to toggle source

Returns whether this class is an abstract class or not.

# File lib/active_record/base.rb, line 831
def abstract_class?
  defined?(@abstract_class) && @abstract_class == true
end
arel_engine() click to toggle source
# File lib/active_record/base.rb, line 853
def arel_engine
  @arel_engine ||= begin
    if self == ActiveRecord::Base
      Arel::Table.engine
    else
      connection_handler.connection_pools[name] ? self : superclass.arel_engine
    end
  end
end
arel_table() click to toggle source
# File lib/active_record/base.rb, line 849
def arel_table
  @arel_table ||= Arel::Table.new(table_name, arel_engine)
end
attr_readonly(*attributes) click to toggle source

Attributes listed as readonly will be used to create a new record but update operations will ignore these fields.

# File lib/active_record/base.rb, line 521
def attr_readonly(*attributes)
  write_inheritable_attribute(:attr_readonly, Set.new(attributes.map { |a| a.to_s }) + (readonly_attributes || []))
end
attribute_method?(attribute) click to toggle source
# File lib/active_record/base.rb, line 751
def attribute_method?(attribute)
  super || (table_exists? && column_names.include?(attribute.to_s.sub(/=$/, '')))
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.

If B < A and C < B and if A is an abstract_class then both B.base_class and C.base_class would return B as the answer since A is an abstract_class.

# File lib/active_record/base.rb, line 823
def base_class
  class_of_active_record_descendant(self)
end
colorize_logging(*args) click to toggle source
# File lib/active_record/base.rb, line 432
def colorize_logging(*args)
  ActiveSupport::Deprecation.warn "ActiveRecord::Base.colorize_logging and " <<
    "config.active_record.colorize_logging are deprecated. Please use " <<
    "Rails::LogSubscriber.colorize_logging or config.colorize_logging instead", caller
end
Also aliased as: colorize_logging=
colorize_logging=(*args) click to toggle source
Alias for: colorize_logging
column_names() click to toggle source

Returns an array of column names as strings.

# File lib/active_record/base.rb, line 691
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 677
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 686
def columns_hash
  @columns_hash ||= Hash[columns.map { |column| [column.name, column] }]
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 358
cattr_accessor :configurations, :instance_writer => false
connected?() click to toggle source

Returns true if Active Record is connected.

# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 101
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 88
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, :instance_writer => false
connection_pool() click to toggle source
# File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 92
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 697
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 514
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 492
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
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 403
cattr_accessor :default_timezone, :instance_writer => false
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 776
def descends_from_active_record?
  if superclass.abstract_class?
    superclass.descends_from_active_record?
  else
    superclass == Base || !columns_hash.include?(inheritance_column)
  end
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 "active_record/connection_adapters/#{spec[:adapter]}_adapter"
      rescue LoadError => e
        raise "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{e})"
      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
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 466
def find_by_sql(sql)
  connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) }
end
inheritance_column() click to toggle source

Defines the column name for use with single table inheritance. Use set_inheritance_column to set a different value.

# File lib/active_record/base.rb, line 610
def inheritance_column
  @inheritance_column ||= "type"
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 790
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
logger click to toggle source

Accepts a logger conforming to the interface of Log4r or the default Ruby 1.8+ Logger class, which is then passed on to any new database connections made and which can be retrieved on both a class and instance level by calling logger.

# File lib/active_record/base.rb, line 317
cattr_accessor :logger, :instance_writer => false
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 1393
def initialize(attributes = nil)
  @attributes = attributes_from_column_definition
  @attributes_cache = {}
  @new_record = true
  @readonly = false
  @destroyed = false
  @marked_for_destruction = false
  @previously_changed = {}
  @changed_attributes = {}

  ensure_proper_type

  populate_with_current_scope_attributes
  self.attributes = attributes unless attributes.nil?

  result = yield self if block_given?
  _run_initialize_callbacks
  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 396
cattr_accessor :pluralize_table_names, :instance_writer => false
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 368
cattr_accessor :primary_key_prefix_type, :instance_writer => false
quoted_table_name() click to toggle source

Returns a quoted version of the table name, used to construct SQL statements.

# File lib/active_record/base.rb, line 595
def quoted_table_name
  @quoted_table_name ||= connection.quote_table_name(table_name)
end
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 526
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 105
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 741
def reset_column_information
  undefine_attribute_methods
  @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @inheritance_column = nil
  @arel_engine = @relation = @arel_table = nil
end
respond_to?(method_id, include_private = false) click to toggle source
# File lib/active_record/base.rb, line 835
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 96
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 414
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 545
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 551
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 647
def set_inheritance_column(value = nil, &block)
  define_attr_method :inheritance_column, value, &block
end
Also aliased as: inheritance_column=
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 666
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. If the value is nil or false then the value returned by the given block is used.

class Project < ActiveRecord::Base
  set_table_name "project"
end
# File lib/active_record/base.rb, line 632
def set_table_name(value = nil, &block)
  @quoted_table_name = nil
  define_attr_method :table_name, value, &block
end
Also aliased as: table_name=
sti_name() click to toggle source
# File lib/active_record/base.rb, line 845
def sti_name
  store_full_sti_class ? name : name.demodulize
end
subclasses() click to toggle source
# File lib/active_record/base.rb, line 324
def subclasses
  descendants
end
table_exists?() click to toggle source

Indicates whether the table associated with this class exists

# File lib/active_record/base.rb, line 672
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 590
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 381
class_attribute :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 388
class_attribute :table_name_suffix, :instance_writer => false
timestamped_migrations click to toggle source

Specify whether or not to use timestamps for migration versions

# File lib/active_record/base.rb, line 420
cattr_accessor :timestamped_migrations , :instance_writer => false

Protected Class Methods

aggregate_mapping(reflection) click to toggle source
# File lib/active_record/base.rb, line 1242
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 1205
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 1177
def compute_type(type_name)
  if type_name.match(/^::/)
    # If the type is prefixed with a scope operator then we assume that
    # the type_name is an absolute reference.
    ActiveSupport::Dependencies.constantize(type_name)
  else
    # Build a list of candidates to search for
    candidates = []
    name.scan(/::|$/) { candidates.unshift "#{$`}::#{type_name}" }
    candidates << type_name

    candidates.each do |candidate|
      begin
        constant = ActiveSupport::Dependencies.constantize(candidate)
        return constant if candidate == constant.to_s
      rescue NameError => e
        # We don't want to swallow NoMethodError < NameError errors
        raise e unless e.instance_of?(NameError)
      rescue ArgumentError
      end
    end

    raise NameError, "uninitialized constant #{candidates.first}"
  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

default_scope is also applied while creating/building a record. It is not applied while updating a record.

class Article < ActiveRecord::Base
  default_scope where(:published => true)
end

Article.new.published    # => true
Article.create.published # => true
# File lib/active_record/base.rb, line 1162
def default_scope(options = {})
  reset_scoped_methods
  self.default_scoping << construct_finder_arel(options, default_scoping.pop)
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 1258
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 = self.table_name) click to toggle source
Alias for: sanitize_sql
sanitize_sql(condition, table_name = self.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 1312
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)
  elsif statement.blank?
    statement
  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 1234
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 = self.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 1220
def sanitize_sql_for_conditions(condition, table_name = self.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 = self.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 1303
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 = self.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 1291
def sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name)
  attrs = expand_hash_conditions_for_aggregates(attrs)

  table = Arel::Table.new(self.table_name, :engine => arel_engine, :as => default_table_name)
  builder = PredicateBuilder.new(arel_engine)
  builder.build_from_hash(attrs, table).map{ |b| b.to_sql }.join(' AND ')
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 1128
def with_exclusive_scope(method_scoping = {}, &block)
  if method_scoping.values.any? { |e| e.is_a?(ActiveRecord::Relation) }
    raise ArgumentError, New finder API can not be used with_exclusive_scope. You can either call unscoped to get an anonymous scope not bound to the default_scope:  User.unscoped.where(:active => true)Or call unscoped with a block:  User.unscoped do    User.where(:active => true).all  end
  end
  with_scope(method_scoping, :overwrite, &block)
end
with_scope(method_scoping = {}, action = :merge, &block) click to toggle source

with_scope lets you apply options to inner block incrementally. It takes a hash and the keys must be :find or :create. :find parameter is Relation while :create parameters are an attributes hash.

class Article < ActiveRecord::Base
  def self.create_with_scope
    with_scope(:find => where(: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 where, includes, and joins operations in Relation, which are merged.

joins operations 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 => where(:blog_id => 1).limit(1), :create => { :blog_id => 1 }) do
      with_scope(:find => limit(10)) do
        all # => SELECT * from articles WHERE blog_id = 1 LIMIT 10
      end
      with_scope(:find => where(:author_id => 3)) do
        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 => where(:blog_id => 1).limit(1)) do
      with_exclusive_scope(:find => limit(10)) do
        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 1087
def with_scope(method_scoping = {}, action = :merge, &block)
  method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping)

  if method_scoping.is_a?(Hash)
    # Dup first and second level of hash (method and params).
    method_scoping = method_scoping.dup
    method_scoping.each do |method, params|
      method_scoping[method] = params.dup unless params == true
    end

    method_scoping.assert_valid_keys([ :find, :create ])
    relation = construct_finder_arel(method_scoping[:find] || {})

    if current_scoped_methods && current_scoped_methods.create_with_value && method_scoping[:create]
      scope_for_create = if action == :merge
        current_scoped_methods.create_with_value.merge(method_scoping[:create])
      else
        method_scoping[:create]
      end

      relation = relation.create_with(scope_for_create)
    else
      scope_for_create = method_scoping[:create]
      scope_for_create ||= current_scoped_methods.create_with_value if current_scoped_methods
      relation = relation.create_with(scope_for_create) if scope_for_create
    end

    method_scoping = relation
  end

  method_scoping = current_scoped_methods.merge(method_scoping) if current_scoped_methods && action ==  :merge

  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 comparison_object is the same exact object, or comparison_object is of the same type and self has an ID and it is equal to comparison_object.id.

Note that new records are different from any other record by definition, unless the other record is the receiver itself. Besides, if you fetch existing records with select and leave the ID out, you’re on your own, this predicate will return false.

Note also that destroying a record preserves its ID in the model instance, so deleted models are still comparable.

# File lib/active_record/base.rb, line 1618
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 1517
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 1523
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 1585
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 1510
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 1599
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 1566
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 1547
def attributes=(new_attributes, guard_protected_attributes = true)
  return unless new_attributes.is_a?(Hash)
  attributes = new_attributes.stringify_keys

  multi_parameter_attributes = []
  attributes = sanitize_for_mass_assignment(attributes) if guard_protected_attributes

  attributes.each do |k, v|
    if k.include?("(")
      multi_parameter_attributes << [ k, v ]
    else
      respond_to?(:"#{k}=") ? send(:"#{k}=", v) : raise(UnknownAttributeError, "unknown attribute: #{k}")
    end
  end

  assign_multiparameter_attributes(multi_parameter_attributes)
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 1489
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
column_for_attribute(name) click to toggle source

Returns the column object for the named attribute.

# File lib/active_record/base.rb, line 1605
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
dup() click to toggle source

Returns duplicated record with unfreezed attributes.

# File lib/active_record/base.rb, line 1646
def dup
  obj = super
  obj.instance_variable_set('@attributes', @attributes.dup)
  obj
end
eql?(comparison_object) click to toggle source

Delegates to ==

# File lib/active_record/base.rb, line 1625
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 1636
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 1641
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 1505
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 1631
def hash
  id.hash
end
init_with(coder) click to toggle source

Initialize an empty model object from coder. coder must contain the attributes necessary for initializing an empty model object. For example:

class Post < ActiveRecord::Base
end

post = Post.allocate
post.init_with('attributes' => { 'title' => 'hello world' })
post.title # => 'hello world'
# File lib/active_record/base.rb, line 1447
def init_with(coder)
  @attributes = coder['attributes']
  @attributes_cache, @previously_changed, @changed_attributes = {}, {}, {}
  @new_record = @readonly = @destroyed = @marked_for_destruction = false
  _run_find_callbacks
  _run_initialize_callbacks
end
initialize_copy(other) click to toggle source

Cloned objects have no id assigned and are treated as new records. Note that this is a “shallow” clone as 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 1416
def initialize_copy(other)
  _run_after_initialize_callbacks if respond_to?(:_run_after_initialize_callbacks)
  cloned_attributes = other.clone_attributes(:read_attribute_before_type_cast)
  cloned_attributes.delete(self.class.primary_key)

  @attributes = cloned_attributes

  @changed_attributes = {}
  attributes_from_column_definition.each do |attr, orig_value|
    @changed_attributes[attr] = orig_value if field_changed?(attr, orig_value, @attributes[attr])
  end

  clear_aggregation_cache
  clear_association_cache
  @attributes_cache = {}
  @new_record = true
  ensure_proper_type

  populate_with_current_scope_attributes
end
inspect() click to toggle source

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

# File lib/active_record/base.rb, line 1664
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
readonly!() click to toggle source

Marks this record as read only.

# File lib/active_record/base.rb, line 1659
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 1654
def readonly?
  @readonly
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 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 1477
def to_param
  # We can't use alias_method here, because method 'id' optimizes itself on the fly.
  id && id.to_s # Be sure to stringify the id for routes
end

Protected Instance Methods

clone_attribute_value(reader_method, attribute_name) click to toggle source
# File lib/active_record/base.rb, line 1681
def clone_attribute_value(reader_method, attribute_name)
  value = send(reader_method, attribute_name)
  value.duplicable? ? value.clone : value
rescue TypeError, NoMethodError
  value
end
clone_attributes(reader_method = :read_attribute, attributes = {}) click to toggle source
# File lib/active_record/base.rb, line 1674
def clone_attributes(reader_method = :read_attribute, attributes = {})
  attribute_names.each do |name|
    attributes[name] = clone_attribute_value(reader_method, name)
  end
  attributes
end

[Validate]

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