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Module: ActiveRecord::AttributeMethods::ClassMethods

Relationships & Source Files
Defined in: activerecord/lib/active_record/attribute_methods.rb

Instance Attribute Summary

Instance Method Summary

Instance Attribute Details

#attribute_methods_generated? ⇒ Boolean (readonly)

This method is for internal use only.
[ GitHub ] 

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 118



def attribute_methods_generated? # :nodoc:
  @attribute_methods_generated
end


  







Instance Method Details



  

    #_has_attribute?(attr_name)  ⇒ Boolean 
  

  

    This method is for internal use only.
  



  

    
  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 288



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


  








  

    #alias_attribute(new_name, old_name)  
  



  

    
Allows you to make aliases for attributes.


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

person = {Person.create}(name: 'Bob')
person.name     # => "Bob"
person.nickname # => "Bob"


The alias can also be used for querying:


{Person.where}(nickname: "Bob")
#### SELECT "people".* FROM "people" WHERE "people"."name" = "Bob"

  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 85



def alias_attribute(new_name, old_name)
  super

  include AliasResolution unless include?(AliasResolution)

  if @alias_attributes_mass_generated
    ActiveSupport::CodeGenerator.batch(generated_attribute_methods, __FILE__, __LINE__) do |code_generator|
      generate_alias_attribute_methods(code_generator, new_name, old_name)
    end
  end
end


  








  

    #alias_attribute_method_definition(code_generator, pattern, new_name, old_name)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 107



def alias_attribute_method_definition(code_generator, pattern, new_name, old_name) # :nodoc:
  old_name = old_name.to_s

  if !abstract_class? && !has_attribute?(old_name)
    raise ArgumentError, "#{self.name} model aliases `#{old_name}`, but `#{old_name}` is not an attribute. " \
      "Use `alias_method :#{new_name}, :#{old_name}` or define the method manually."
  else
    define_attribute_method_pattern(pattern, old_name, owner: code_generator, as: new_name, override: true)
  end
end


  








  

    #attribute_method?(attribute)  ⇒ Boolean 
  



  

    
Returns true if attribute is an attribute method and table exists,
false otherwise.


class Person < {ActiveRecord::Base}
end

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

  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 248



def attribute_method?(attribute)
  super || (table_exists? && column_names.include?(attribute.to_s.delete_suffix("=")))
end


  








  

    #attribute_names  
  



  

    
Returns an array of column names as strings if it's not an abstract class and
table exists. Otherwise it returns an empty array.


class Person < {ActiveRecord::Base}
end

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

  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 262



def attribute_names
  @attribute_names ||= if !abstract_class? && table_exists?
    attribute_types.keys
  else
    []
  end.freeze
end


  








  

    #dangerous_attribute_method?(name)  ⇒ Boolean 
  

  

    This method is for internal use only.
  



  

    
A method name is 'dangerous' if it is already (re)defined by Active Record, but
not by any ancestors. (So 'puts' is not dangerous but 'save' is.)

  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 205



def dangerous_attribute_method?(name) # :nodoc:
  ::ActiveRecord::AttributeMethods.dangerous_attribute_methods.include?(name.to_s)
end


  








  

    #dangerous_class_method?(method_name)  ⇒ Boolean 
  



  

    
A class method is 'dangerous' if it is already (re)defined by Active Record, but
not by any ancestors. (So 'puts' is not dangerous but 'new' is.)

  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 223



def dangerous_class_method?(method_name)
  return true if RESTRICTED_CLASS_METHODS.include?(method_name.to_s)

  if Base.respond_to?(method_name, true)
    if Object.respond_to?(method_name, true)
      Base.method(method_name).owner != Object.method(method_name).owner
    else
      true
    end
  else
    false
  end
end


  








  

    #define_attribute_methods  
  

  

    This method is for internal use only.
  



  

    
Generates all the attribute related methods for columns in the database
accessors, mutators and query methods.

  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 124



def define_attribute_methods # :nodoc:
  return false if @attribute_methods_generated
  # Use a mutex; we don't want two threads simultaneously trying to define
  # attribute methods.
  GeneratedAttributeMethods::LOCK.synchronize do
    return false if @attribute_methods_generated

    superclass.define_attribute_methods unless base_class?

    unless abstract_class?
      load_schema
      super(attribute_names)
      define_id_value if _has_attribute?("id") && !_has_attribute?("id_value")
    end

    generate_alias_attributes

    @attribute_methods_generated = true
  end

  true
end


  








  

    #define_id_value   (private)
  



  

    
Composite primary key models get a real alias, which makes
where(id_value: ...) work. Other models get a plain reader, so
they don't take the alias resolution slow path.

  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 305



def define_id_value
  if composite_primary_key?
    alias_attribute :id_value, :id
  elsif !attribute_alias?("id_value")
    ActiveSupport::CodeGenerator.batch(generated_attribute_methods, __FILE__, __LINE__) do |owner|
      define_method_attribute("id", owner: owner, as: "id_value")
    end
  end
end


  








  

    #eagerly_generate_alias_attribute_methods(_new_name, _old_name)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 97



def eagerly_generate_alias_attribute_methods(_new_name, _old_name) # :nodoc:
  # alias attributes in Active Record are lazily generated
end


  








  

    #generate_alias_attribute_methods(code_generator, new_name, old_name)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 101



def generate_alias_attribute_methods(code_generator, new_name, old_name) # :nodoc:
  attribute_method_patterns.each do |pattern|
    alias_attribute_method_definition(code_generator, pattern, new_name, old_name)
  end
end


  








  

    #generate_alias_attributes  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 147



def generate_alias_attributes # :nodoc:
  superclass.generate_alias_attributes unless superclass == Base

  return if @alias_attributes_mass_generated

  ActiveSupport::CodeGenerator.batch(generated_attribute_methods, __FILE__, __LINE__) do |code_generator|
    aliases_by_attribute_name.each do |old_name, new_names|
      new_names.each do |new_name|
        generate_alias_attribute_methods(code_generator, new_name, old_name)
      end
    end
  end

  @alias_attributes_mass_generated = true
end


  








  

    #has_attribute?(attr_name)  ⇒ Boolean 
  



  

    
Returns true if the given attribute exists, otherwise false.


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

{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 282



def has_attribute?(attr_name)
  attr_name = attr_name.to_s
  attr_name = attribute_aliases[attr_name] || attr_name
  attribute_types.key?(attr_name)
end


  








  

    #inherited(child_class)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 293



def inherited(child_class)
  super
  child_class.initialize_generated_modules
  child_class.class_eval do
    @alias_attributes_mass_generated = false
    @attribute_names = nil
  end
end


  








  

    #initialize_generated_modules  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 57



def initialize_generated_modules # :nodoc:
  @generated_attribute_methods = const_set(:GeneratedAttributeMethods, GeneratedAttributeMethods.new)
  private_constant :GeneratedAttributeMethods
  @attribute_methods_generated = false
  @alias_attributes_mass_generated = false
  include @generated_attribute_methods

  super
end


  








  

    #instance_method_already_implemented?(method_name)  ⇒ Boolean 
  



  

    
Raises an ::ActiveRecord::DangerousAttributeError exception when an
Active Record method is defined in the model, otherwise false.


class Person < {ActiveRecord::Base}
  def save
    'already defined by Active Record'
  end
end

{Person.instance_method_already_implemented?}(:save)
#### => {ActiveRecord::DangerousAttributeError}: save is defined by Active Record. Check to make sure that you don't have an attribute or method with the same name.

{Person.instance_method_already_implemented?}(:name)
#### => false

  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 187



def instance_method_already_implemented?(method_name)
  if dangerous_attribute_method?(method_name)
    raise DangerousAttributeError, "#{method_name} is defined by Active Record. Check to make sure that you don't have an attribute or method with the same name."
  end

  if superclass == Base
    super
  else
    # If ThisClass < ... < SomeSuperClass < ... < Base and SomeSuperClass
    # defines its own attribute method, then we don't want to override that.
    defined = method_defined_within?(method_name, superclass, Base) &&
      ! superclass.instance_method(method_name).owner.is_a?(GeneratedAttributeMethods)
    defined || super
  end
end


  








  

    #method_defined_within?(name, klass, superklass = klass.superclass)  ⇒ Boolean 
  

  

    This method is for internal use only.
  



  

    
  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 209



def method_defined_within?(name, klass, superklass = klass.superclass) # :nodoc:
  if klass.method_defined?(name) || klass.private_method_defined?(name)
    if superklass.method_defined?(name) || superklass.private_method_defined?(name)
      klass.instance_method(name).owner != superklass.instance_method(name).owner
    else
      true
    end
  else
    false
  end
end


  








  

    #undefine_attribute_methods  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/attribute_methods.rb', line 163



def undefine_attribute_methods # :nodoc:
  GeneratedAttributeMethods::LOCK.synchronize do
    super if @attribute_methods_generated
    @attribute_methods_generated = false
    @alias_attributes_mass_generated = false
  end
end