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Module: ActiveRecord::AttributeMethods

Constant Summary

::ActiveModel::AttributeMethods - Included

CALL_COMPILABLE_REGEXP, NAME_COMPILABLE_REGEXP

::ActiveModel::AttributeMethods - Attributes & Methods

Class Method Summary

::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

::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?,
#respond_to_without_attributes?

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.
#_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

#method_missing(name) (private)

[ GitHub ] 

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 472



def method_missing(name, ...)
  unless self.class.attribute_methods_generated?
    if self.class.method_defined?(name)
      # The method is explicitly defined in the model, but calls a generated
      # method with super. So we must resume the call chain at the right step.
      last_method = method(name)
      last_method = last_method.super_method while last_method.super_method
      self.class.define_attribute_methods
      if last_method.super_method
        return last_method.super_method.call(...)
      end
    elsif self.class.define_attribute_methods
      # Some attribute methods weren't generated yet, we retry the call
      return public_send(name, ...)
    end
  end

  super
end


  







DSL Calls




included

  [ GitHub ]


  


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# File 'activerecord/lib/active_record/attribute_methods.rb', line 11



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 71



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


  








  

    .attribute_aliases?  ⇒ Boolean  (rw)
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 71



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


  








  

    .attribute_method_patterns   (rw)
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 72



class_attribute :attribute_method_patterns, instance_writer: false, default: [ ClassMethods::AttributeMethodPattern.new ]


  








  

    .attribute_method_patterns?  ⇒ Boolean  (rw)
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 72



class_attribute :attribute_method_patterns, instance_writer: false, default: [ ClassMethods::AttributeMethodPattern.new ]


  







Class Method Details



  

    .dangerous_attribute_methods  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 30



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 71



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


  








  

    #attribute_aliases?  ⇒ Boolean  (readonly)
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 71



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


  








  

    #attribute_method_patterns   (readonly)
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 72



class_attribute :attribute_method_patterns, instance_writer: false, default: [ ClassMethods::AttributeMethodPattern.new ]


  








  

    #attribute_method_patterns?  ⇒ Boolean  (readonly)
  

  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 72



class_attribute :attribute_method_patterns, instance_writer: false, default: [ ClassMethods::AttributeMethodPattern.new ]


  







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 412



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 425



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 319



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 457



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 362



def attribute_for_inspect(attr_name)
  attr_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 492



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 331



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 384



def attribute_present?(attr_name)
  attr_name = attr_name.to_s
  attr_name = self.class.attribute_aliases[attr_name] || 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 343



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 512



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 501



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 496



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 520



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 313



def has_attribute?(attr_name)
  attr_name = attr_name.to_s
  attr_name = self.class.attribute_aliases[attr_name] || attr_name
  @attributes.key?(attr_name)
end


  








  

    #pk_attribute?(name)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 536



def pk_attribute?(name)
  name == @primary_key
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 288



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
    if name = self.class.symbol_column_to_string(name.to_sym)
      return _has_attribute?(name)
    end
  end

  true
end


  








  

    #respond_to_missing?(name, include_private = false)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 462



def respond_to_missing?(name, include_private = false)
  if self.class.define_attribute_methods
    # Some methods weren't defined yet.
    return true if self.class.method_defined?(name)
    return true if include_private && self.class.private_method_defined?(name)
  end

  super
end