Module: ActiveRecord::AttributeMethods::ClassMethods
Relationships & Source Files | |
Defined in: | activerecord/lib/active_record/attribute_methods.rb |
Instance Method Summary
- #alias_attribute(new_name, old_name)
-
#attribute_method?(attribute) ⇒ Boolean
Returns
true
ifattribute
is an attribute method and table exists,false
otherwise. -
#attribute_names
Returns an array of column names as strings if it’s not an abstract class and table exists.
-
#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.
-
#has_attribute?(attr_name) ⇒ Boolean
Returns true if the given attribute exists, otherwise false.
-
#instance_method_already_implemented?(method_name) ⇒ Boolean
Raises an
::ActiveRecord::DangerousAttributeError
exception when an Active Record method is defined in the model, otherwisefalse
.
Instance Method Details
#alias_attribute(new_name, old_name)
[ GitHub ]# File 'activerecord/lib/active_record/attribute_methods.rb', line 53
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
#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
# File 'activerecord/lib/active_record/attribute_methods.rb', line 229
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"]
# File 'activerecord/lib/active_record/attribute_methods.rb', line 241
def attribute_names @attribute_names ||= if !abstract_class? && table_exists? attribute_types.keys else [] end.freeze 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.)
# File 'activerecord/lib/active_record/attribute_methods.rb', line 206
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
#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
# File 'activerecord/lib/active_record/attribute_methods.rb', line 259
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
#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
# File 'activerecord/lib/active_record/attribute_methods.rb', line 170
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