Module: ActiveRecord::AttributeMethods

Relationships & Source Files
Namespace Children
Modules: `AliasResolution`, `BeforeTypeCast`, `ClassMethods`, `CompositePrimaryKey`, `Dirty`, `PrimaryKey`, `Query`, `Read`, `Serialization`, `TimeZoneConversion`, `Write`
Classes: `GeneratedAttributeMethods`
Extension / Inclusion / Inheritance Descendants
Included In: `Base`
Super Chains via Extension / Inclusion / Inheritance
Class Chain: self, `::ActiveSupport::Concern`, `::ActiveSupport::Autoload`
Instance Chain: self, `::ActiveModel::AttributeMethods`
Defined in:	activerecord/lib/active_record/attribute_methods.rb, activerecord/lib/active_record.rb, activerecord/lib/active_record/attribute_methods/before_type_cast.rb, activerecord/lib/active_record/attribute_methods/composite_primary_key.rb, activerecord/lib/active_record/attribute_methods/dirty.rb, activerecord/lib/active_record/attribute_methods/primary_key.rb, activerecord/lib/active_record/attribute_methods/query.rb, activerecord/lib/active_record/attribute_methods/read.rb, activerecord/lib/active_record/attribute_methods/serialization.rb, activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb, activerecord/lib/active_record/attribute_methods/write.rb

Overview

===============================

Constant Summary

RESTRICTED_CLASS_METHODS =
# File 'activerecord/lib/active_record/attribute_methods.rb', line 37
```
%w(private public protected allocate new name superclass).freeze
```

`::ActiveModel::AttributeMethods` - Included

CALL_COMPILABLE_REGEXP, EMPTY_HASH, NAME_COMPILABLE_REGEXP

`::ActiveModel::AttributeMethods` - Attributes & Methods

.attribute_aliases rw
#attribute_aliases readonly
.attribute_aliases? ⇒ Boolean rw
#attribute_aliases? ⇒ Boolean readonly
.attribute_method_patterns rw
#attribute_method_patterns readonly
.attribute_method_patterns? ⇒ Boolean rw
#attribute_method_patterns? ⇒ Boolean readonly

Class Method Summary

.dangerous_attribute_methods Internal use only

`::ActiveSupport::Concern` - Extended

class_methods	Define class methods from given block.
included	Evaluate given block in context of base class, so that you can write class macros here.
prepended	Evaluate given block in context of base class, so that you can write class macros here.
append_features, prepend_features

`::ActiveSupport::Autoload` - Extended

autoload, autoload_at, autoload_under, eager_autoload, eager_load!

Instance Method Summary

#[](attr_name)

Returns the value of the attribute identified by attr_name after it has been type cast.
#[]=(attr_name, value)

Updates the attribute identified by attr_name using the specified value.
#accessed_fields

Returns the name of all database fields which have been read from this model.
#attribute_for_inspect(attr_name)

Returns an #inspect-like string for the value of the attribute attr_name.
#attribute_names

Returns an array of names for the attributes available on this object.
#attribute_present?(attr_name) ⇒ Boolean

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).
#attributes

Returns a hash of all the attributes with their names as keys and the values of the attributes as values.
#has_attribute?(attr_name) ⇒ Boolean

Returns true if the given attribute is in the attributes hash, otherwise false.
#respond_to?(name, include_private = false) ⇒ Boolean

A Person object with a name attribute can ask person.respond_to?(:name), person.respond_to?(:name=), and person.respond_to?(:name?) which will all return true.
#attribute_method?(attr_name) ⇒ Boolean private
#attributes_for_create(attribute_names) private

Filters out the virtual columns and also primary keys, from the attribute names, when the primary key is to be generated (e.g.
#attributes_for_update(attribute_names) private

Filters the primary keys, readonly attributes and virtual columns from the attribute names.
#attributes_with_values(attribute_names) private
#format_for_inspect(name, value) private
#pk_attribute?(name) ⇒ Boolean private
#_has_attribute?(attr_name) ⇒ Boolean Internal use only
#resolve_alias(attr_name) Internal use only

This gets overridden on models that use attribute aliases.

`::ActiveModel::AttributeMethods` - Included

#attribute_missing	`attribute_missing` is like `method_missing`, but for attributes.
#method_missing	Allows access to the object attributes, which are held in the hash returned by #attributes, as though they were first-class methods.
#respond_to?	A `Person` instance with a `name` attribute can ask `person.respond_to?(:name)`, `person.respond_to?(:name=)`, and `person.respond_to?(:name?)` which will all return `true`.
#respond_to_without_attributes?	Checks whether the object responds to `method` without searching the attributes.
#_read_attribute, #attribute_method?,
#matched_attribute_method	Returns a struct representing the matching attribute method.
#missing_attribute

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class ActiveModel::AttributeMethods

DSL Calls

included

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 12


included do
  initialize_generated_modules
  include Read
  include Write
  include BeforeTypeCast
  include Query
  include PrimaryKey
  include TimeZoneConversion
  include Dirty
  include Serialization
end

Class Attribute Details

.attribute_aliases (rw)

[ GitHub ]

# File 'activemodel/lib/active_model/attribute_methods.rb', line 64


class_attribute :attribute_aliases, instance_writer: false, default: {}.freeze

.attribute_aliases? ⇒ `Boolean` (rw)

[ GitHub ]

# File 'activemodel/lib/active_model/attribute_methods.rb', line 64


class_attribute :attribute_aliases, instance_writer: false, default: {}.freeze

.attribute_method_patterns (rw)

[ GitHub ]

# File 'activemodel/lib/active_model/attribute_methods.rb', line 66


class_attribute :attribute_method_patterns, instance_writer: false, default: ClassMethods::AttributeMethodPatternSet.new([ ClassMethods::AttributeMethodPattern::BASE ])

.attribute_method_patterns? ⇒ `Boolean` (rw)

[ GitHub ]

# File 'activemodel/lib/active_model/attribute_methods.rb', line 66


class_attribute :attribute_method_patterns, instance_writer: false, default: ClassMethods::AttributeMethodPatternSet.new([ ClassMethods::AttributeMethodPattern::BASE ])

Class Method Details

.dangerous_attribute_methods

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 44


def dangerous_attribute_methods # :nodoc:
  @dangerous_attribute_methods ||= (
    Base.instance_methods +
    Base.private_instance_methods -
    Base.superclass.instance_methods -
    Base.superclass.private_instance_methods +
    %i[__id__ dup freeze frozen? hash class clone]
  ).map { |m| -m.to_s }.to_set.freeze
end

Instance Attribute Details

#attribute_aliases (readonly)

[ GitHub ]

# File 'activemodel/lib/active_model/attribute_methods.rb', line 64


class_attribute :attribute_aliases, instance_writer: false, default: {}.freeze

#attribute_aliases? ⇒ `Boolean` (readonly)

[ GitHub ]

# File 'activemodel/lib/active_model/attribute_methods.rb', line 64


class_attribute :attribute_aliases, instance_writer: false, default: {}.freeze

#attribute_method_patterns (readonly)

[ GitHub ]

# File 'activemodel/lib/active_model/attribute_methods.rb', line 66


class_attribute :attribute_method_patterns, instance_writer: false, default: ClassMethods::AttributeMethodPatternSet.new([ ClassMethods::AttributeMethodPattern::BASE ])

#attribute_method_patterns? ⇒ `Boolean` (readonly)

[ GitHub ]

# File 'activemodel/lib/active_model/attribute_methods.rb', line 66


class_attribute :attribute_method_patterns, instance_writer: false, default: ClassMethods::AttributeMethodPatternSet.new([ ClassMethods::AttributeMethodPattern::BASE ])

Instance Method Details

#[](attr_name)

Returns the value of the attribute identified by attr_name after it has been type cast. (For information about specific type casting behavior, see the types under ::ActiveModel::Type.)

class Person < {ActiveRecord::Base}
  belongs_to :organization
end

person = {Person.new}(name: "Francesco", date_of_birth: "2004-12-12")
person[:name]            # => "Francesco"
person[:date_of_birth]   # => {Date.new}(2004, 12, 12)
person[:organization_id] # => nil

Raises ::ActiveModel::MissingAttributeError if the attribute is missing. Note, however, that the id attribute will never be considered missing.

person = {Person.select}(:name).first
person[:name]            # => "Francesco"
person[:date_of_birth]   # => {ActiveModel::MissingAttributeError}: missing attribute 'date_of_birth' for Person
person[:organization_id] # => {ActiveModel::MissingAttributeError}: missing attribute 'organization_id' for Person
person[:id]              # => nil

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 474


def [](attr_name)
  read_attribute(attr_name) { |n| missing_attribute(n, caller) }
end

#[]=(attr_name, value)

Updates the attribute identified by attr_name using the specified value. The attribute value will be type cast upon being read.

class Person < {ActiveRecord::Base}
end

person = {Person.new}
person[:date_of_birth] = "2004-12-12"
person[:date_of_birth] # => {Date.new}(2004, 12, 12)

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 489


def []=(attr_name, value)
  write_attribute(attr_name, value)
end

#_has_attribute?(attr_name) ⇒ `Boolean`

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 371


def _has_attribute?(attr_name) # :nodoc:
  @attributes.key?(attr_name)
end

#accessed_fields

Returns the name of all database fields which have been read from this model. This can be useful in development mode to determine which fields need to be selected. For performance critical pages, selecting only the required fields can be an easy performance win (assuming you aren't using all of the fields on the model).

For example:

class PostsController < {ActionController::Base}
  after_action :print_accessed_fields, only: :index

  def index
    @posts = Post.all
  end

  private
    def print_accessed_fields
      p @posts.first.accessed_fields
    end
end

Which allows you to quickly change your code to:

class PostsController < {ActionController::Base}
  def index
    @posts = Post.select(:id, :title, :author_id, :updated_at)
  end
end

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 525


def accessed_fields
  @attributes.accessed
end

#attribute_for_inspect(attr_name)

Returns an #inspect-like string for the value of the attribute attr_name. ::String attributes are truncated up to 50 characters. 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 ...\""

person.attribute_for_inspect(:created_at)
#### => "\"2012-10-22 00:15:07.000000000 +0000\""

person.attribute_for_inspect(:tag_ids)
#### => "[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]"

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 420


def attribute_for_inspect(attr_name)
  attr_name = attr_name.is_a?(Symbol) ? attr_name.name : attr_name.to_s
  attr_name = self.class.attribute_aliases[attr_name] || attr_name
  value = _read_attribute(attr_name)
  format_for_inspect(attr_name, value)
end

#attribute_method?(attr_name) ⇒ `Boolean` (private)

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 530


def attribute_method?(attr_name)
  @attributes&.key?(attr_name)
end

#attribute_names

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

class Person < {ActiveRecord::Base}
end

person = {Person.new}
person.attribute_names
#### => ["id", "created_at", "updated_at", "name", "age"]

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 385


def attribute_names
  @attributes.keys
end

#attribute_present?(attr_name) ⇒ `Boolean`

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). Otherwise, false. Note that it always returns true with boolean attributes.

class Task < {ActiveRecord::Base}
end

task = {Task.new}(title: '', is_done: false)
task.attribute_present?(:title)   # => false
task.attribute_present?(:is_done) # => true
task.title = 'Buy milk'
task.is_done = true
task.attribute_present?(:title)   # => true
task.attribute_present?(:is_done) # => true

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 444


def attribute_present?(attr_name)
  value = read_attribute(attr_name)
  !value.nil? && !(value.respond_to?(:empty?) && value.empty?)
end

#attributes

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

class Person < {ActiveRecord::Base}
end

person = {Person.create}(name: 'Francesco', age: 22)
person.attributes
#### => {"id"=>3, "created_at"=>Sun, 21 Oct 2012 04:53:04, "updated_at"=>Sun, 21 Oct 2012 04:53:04, "name"=>"Francesco", "age"=>22}

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 399


def attributes
  @attributes.to_hash
end

#attributes_for_create(attribute_names) (private)

Filters out the virtual columns and also primary keys, from the attribute names, when the primary key is to be generated (e.g. the id attribute has no value).

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 550


def attributes_for_create(attribute_names)
  attribute_names &= self.class.column_names
  attribute_names.delete_if do |name|
    (pk_attribute?(name) && id.nil?) ||
      column_for_attribute(name).virtual?
  end
end

#attributes_for_update(attribute_names) (private)

Filters the primary keys, readonly attributes and virtual columns from the attribute names.

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 539


def attributes_for_update(attribute_names)
  attribute_names &= self.class.column_names
  attribute_names.delete_if do |name|
    self.class.readonly_attribute?(name) ||
      self.class.counter_cache_column?(name) ||
      column_for_attribute(name).virtual?
  end
end

#attributes_with_values(attribute_names) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 534


def attributes_with_values(attribute_names)
  attribute_names.index_with { |name| @attributes[name] }
end

#format_for_inspect(name, value) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 558


def format_for_inspect(name, value)
  if value.nil?
    value.inspect
  else
    inspected_value = if value.is_a?(String) && value.length > 50
      "#{value[0, 50]}...".inspect
    elsif value.is_a?(Date) || value.is_a?(Time)
      %("#{value.to_fs(:inspect)}")
    else
      value.inspect
    end

    inspection_filter.filter_param(name, inspected_value)
  end
end

#has_attribute?(attr_name) ⇒ `Boolean`

Returns true if the given attribute is in the attributes hash, otherwise false.

class Person < {ActiveRecord::Base}
  alias_attribute :new_name, :name
end

person = {Person.new}
person.has_attribute?(:name)     # => true
person.has_attribute?(:new_name) # => true
person.has_attribute?('age')     # => true
person.has_attribute?(:nothing)  # => false

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 366


def has_attribute?(attr_name)
  attr_name = resolve_alias(attr_name.is_a?(Symbol) ? attr_name.name : attr_name.to_s)
  @attributes.key?(attr_name)
end

#pk_attribute?(name) ⇒ `Boolean` (private)

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 574


def pk_attribute?(name)
  name == @primary_key
end

#resolve_alias(attr_name)

This method is for internal use only.

This gets overridden on models that use attribute aliases. Internal, don't call it!

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 26


def resolve_alias(attr_name) # :nodoc:
  attr_name
end

#respond_to?(name, include_private = false) ⇒ `Boolean`

A Person object with a name attribute can ask person.respond_to?(:name), person.respond_to?(:name=), and person.respond_to?(:name?) which will all return true. It also defines the attribute methods if they have not been generated.

class Person < {ActiveRecord::Base}
end

person = {Person.new}
person.respond_to?(:name)    # => true
person.respond_to?(:name=)   # => true
person.respond_to?(:name?)   # => true
person.respond_to?('age')    # => true
person.respond_to?('age=')   # => true
person.respond_to?('age?')   # => true
person.respond_to?(:nothing) # => false

[ GitHub ]

# File 'activerecord/lib/active_record/attribute_methods.rb', line 340


def respond_to?(name, include_private = false)
  return false unless super

  # If the result is true then check for the select case.
  # For queries selecting a subset of columns, return false for unselected columns.
  if @attributes
    name = name.name if name.is_a?(Symbol)
    return _has_attribute?(name) if self.class.columns_hash.key?(name)
  end

  true
end

Module: ActiveRecord::AttributeMethods

Overview

Constant Summary

::ActiveModel::AttributeMethods - Included

::ActiveModel::AttributeMethods - Attributes & Methods

Class Method Summary

::ActiveSupport::Concern - Extended

::ActiveSupport::Autoload - Extended

Instance Method Summary

::ActiveModel::AttributeMethods - Included

Dynamic Method Handling

DSL Calls

included

Class Attribute Details

.attribute_aliases (rw)

.attribute_aliases? ⇒ Boolean (rw)

.attribute_method_patterns (rw)

.attribute_method_patterns? ⇒ Boolean (rw)

Class Method Details

.dangerous_attribute_methods

Instance Attribute Details

#attribute_aliases (readonly)

#attribute_aliases? ⇒ Boolean (readonly)

#attribute_method_patterns (readonly)

#attribute_method_patterns? ⇒ Boolean (readonly)

Instance Method Details

#[](attr_name)

#[]=(attr_name, value)

#_has_attribute?(attr_name) ⇒ Boolean

#accessed_fields

#attribute_for_inspect(attr_name)

#attribute_method?(attr_name) ⇒ Boolean (private)

#attribute_names

#attribute_present?(attr_name) ⇒ Boolean

#attributes

#attributes_for_create(attribute_names) (private)

#attributes_for_update(attribute_names) (private)

#attributes_with_values(attribute_names) (private)

#format_for_inspect(name, value) (private)

#has_attribute?(attr_name) ⇒ Boolean

#pk_attribute?(name) ⇒ Boolean (private)

#resolve_alias(attr_name)

#respond_to?(name, include_private = false) ⇒ Boolean

`::ActiveModel::AttributeMethods` - Included

`::ActiveModel::AttributeMethods` - Attributes & Methods

`::ActiveSupport::Concern` - Extended

`::ActiveSupport::Autoload` - Extended

`::ActiveModel::AttributeMethods` - Included

.attribute_aliases? ⇒ `Boolean` (rw)

.attribute_method_patterns? ⇒ `Boolean` (rw)

#attribute_aliases? ⇒ `Boolean` (readonly)

#attribute_method_patterns? ⇒ `Boolean` (readonly)

#_has_attribute?(attr_name) ⇒ `Boolean`

#attribute_method?(attr_name) ⇒ `Boolean` (private)

#attribute_present?(attr_name) ⇒ `Boolean`

#has_attribute?(attr_name) ⇒ `Boolean`

#pk_attribute?(name) ⇒ `Boolean` (private)

#respond_to?(name, include_private = false) ⇒ `Boolean`