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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

append_features, class_methods, included

::ActiveSupport::Autoload - Extended

autoload, autoload_at, autoload_under, autoloads, 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.

Dynamic Method Handling

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

DSL Calls

included

[ GitHub ] 


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# 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

  delegate :column_for_attribute, to: :class
end

Class Attribute Details

.attribute_aliases (rw)

[ GitHub ] 

  


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



class_attribute :attribute_aliases, :attribute_method_matchers, instance_writer: false


  








  

    .attribute_aliases?  ⇒ Boolean  (rw)
  

  [ GitHub ]


  

  


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



class_attribute :attribute_aliases, :attribute_method_matchers, instance_writer: false


  








  

    .attribute_method_matchers   (rw)
  

  [ GitHub ]


  

  


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



class_attribute :attribute_aliases, :attribute_method_matchers, instance_writer: false


  








  

    .attribute_method_matchers?  ⇒ Boolean  (rw)
  

  [ GitHub ]


  

  


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



class_attribute :attribute_aliases, :attribute_method_matchers, instance_writer: false


  







Instance Attribute Details



  

    #attribute_aliases   (readonly)
  

  [ GitHub ]


  

  


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



class_attribute :attribute_aliases, :attribute_method_matchers, instance_writer: false


  








  

    #attribute_aliases?  ⇒ Boolean  (readonly)
  

  [ GitHub ]


  

  


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



class_attribute :attribute_aliases, :attribute_method_matchers, instance_writer: false


  








  

    #attribute_method_matchers   (readonly)
  

  [ GitHub ]


  

  


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



class_attribute :attribute_aliases, :attribute_method_matchers, instance_writer: false


  








  

    #attribute_method_matchers?  ⇒ Boolean  (readonly)
  

  [ GitHub ]


  

  


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



class_attribute :attribute_aliases, :attribute_method_matchers, instance_writer: false


  







Instance Method Details



  

    #[](attr_name)  
  



  

    

Returns the value of the attribute identified by attr_name after it has been typecast (for example, “2004-12-12” in a date column is cast to a date object, like Date.new(2004, 12, 12)). It raises ::ActiveModel::MissingAttributeError if the identified attribute is missing.



Note: :id is always present.



Alias for the read_attribute method.



class Person < ActiveRecord::Base
  belongs_to :organization
end

person = Person.new(name: 'Francesco', age: '22')
person[:name] # => "Francesco"
person[:age]  # => 22

person = Person.select('id').first
person[:name]            # => ActiveModel::MissingAttributeError: missing attribute: name
person[:organization_id] # => ActiveModel::MissingAttributeError: missing attribute: organization_id


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 354



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


  








  

    #[]=(attr_name, value)  
  



  

    

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



class Person < ActiveRecord::Base
end

person = Person.new
person[:age] = '22'
person[:age] # => 22
person[:age].class # => Integer


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 368



def []=(attr_name, value)
  write_attribute(attr_name, value)
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, ::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 ...\""

person.attribute_for_inspect(:created_at)
# => "\"2012-10-22 00:15:07\""

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 303



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  
  



  

    

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 271



def attribute_names
  @attributes.keys
end


  








  

    #attribute_present?(attribute)  ⇒ 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 330



def attribute_present?(attribute)
  value = _read_attribute(attribute)
  !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 283



def attributes
  @attributes.to_hash
end


  








  

    #has_attribute?(attr_name)  ⇒ Boolean 
  



  

    

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



class Person < ActiveRecord::Base
end

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


  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 259



def has_attribute?(attr_name)
  @attributes.key?(attr_name.to_s)
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 define 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 235



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

  # If the result is true then check for the select case.
  # For queries selecting a subset of columns, return false for unselected columns.
  # We check defined?(@attributes) not to issue warnings if called on objects that
  # have been allocated but not yet initialized.
  if defined?(@attributes) && self.class.column_names.include?(name)
    return has_attribute?(name)
  end

  return true
end