Module: ActiveRecord::AttributeMethods::ClassMethods

Defined in:
lib/active_record/attribute_methods.rb

Instance Method Summary collapse

Instance Method Details

#_has_attribute?(attr_name) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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

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

#alias_attribute(new_name, old_name) ⇒ Object

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"



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# File 'lib/active_record/attribute_methods.rb', line 66

def alias_attribute(new_name, old_name)
  super

  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) ⇒ Object

:nodoc:



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# File 'lib/active_record/attribute_methods.rb', line 87

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

Returns:

  • (Boolean) 


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

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

#attribute_methods_generated? ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 98

def attribute_methods_generated? # :nodoc:
  @attribute_methods_generated
end

#attribute_names ⇒ Object

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"]



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# File 'lib/active_record/attribute_methods.rb', line 235

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

#dangerous_attribute_method?(name) ⇒ Boolean

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.)

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 182

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.)

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 200

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 ⇒ Object

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



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# File 'lib/active_record/attribute_methods.rb', line 104

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)
      alias_attribute :id_value, :id if _has_attribute?("id")
    end

    @attribute_methods_generated = true

    generate_alias_attributes
  end
  true
end

#eagerly_generate_alias_attribute_methods(_new_name, _old_name) ⇒ Object

:nodoc:



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# File 'lib/active_record/attribute_methods.rb', line 76

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) ⇒ Object

:nodoc:



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# File 'lib/active_record/attribute_methods.rb', line 80

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
  attribute_method_patterns_cache.clear
end

#generate_alias_attributes ⇒ Object

:nodoc:



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# File 'lib/active_record/attribute_methods.rb', line 126

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

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 253

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

#initialize_generated_modules ⇒ Object

:nodoc:



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# File 'lib/active_record/attribute_methods.rb', line 42

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

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 164

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

:nodoc:

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 186

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 ⇒ Object

:nodoc:



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# File 'lib/active_record/attribute_methods.rb', line 142

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