ActiveRecord::Inheritance::ClassMethods (original) (raw)

Methods

A

B

C

D

N

P

S

Attributes

[RW] abstract_class Set this to true if this is an abstract class (see abstract_class?). If you are using inheritance with Active Record and don’t want a class to be considered as part of the STI hierarchy, you must set this to true. ApplicationRecord, for example, is generated as an abstract class. Consider the following default behavior: Shape = Class.new(ActiveRecord::Base) Polygon = Class.new(Shape) Square = Class.new(Polygon) Shape.table_name # => "shapes" Polygon.table_name # => "shapes" Square.table_name # => "shapes" Shape.create! # => #<Shape id: 1, type: nil> Polygon.create! # => #<Polygon id: 2, type: "Polygon"> Square.create! # => #<Square id: 3, type: "Square"> However, when using abstract_class, Shape is omitted from the hierarchy: class Shape < ActiveRecord::Base self.abstract_class = true end Polygon = Class.new(Shape) Square = Class.new(Polygon) Shape.table_name # => nil Polygon.table_name # => "polygons" Square.table_name # => "polygons" Shape.create! # => NotImplementedError: Shape is an abstract class and cannot be instantiated. Polygon.create! # => #<Polygon id: 1, type: nil> Square.create! # => #<Square id: 2, type: "Square"> Note that in the above example, to disallow the creation of a plain Polygon, you should use validates :type, presence: true, instead of setting it as an abstract class. This way, Polygon will stay in the hierarchy, and Active Record will continue to correctly derive the table name.
[R] base_class Returns the first class in the inheritance hierarchy that descends from either an abstract class or from ActiveRecord::Base. Consider the following behaviour: class ApplicationRecord < ActiveRecord::Base self.abstract_class = true end class Shape < ApplicationRecord self.abstract_class = true end Polygon = Class.new(Shape) Square = Class.new(Polygon) ApplicationRecord.base_class # => ApplicationRecord Shape.base_class # => Shape Polygon.base_class # => Polygon Square.base_class # => Polygon

Instance Public methods

Returns whether this class is an abstract class or not.

Source: show | on GitHub

def abstract_class? @abstract_class == true end

Returns whether the class is a base class. See base_class for more information.

Returns true if this does not need STI type condition. Returns false if STI type condition needs to be applied.

Source: show | on GitHub

def descends_from_active_record? if self == Base false elsif superclass.abstract_class? superclass.descends_from_active_record? else superclass == Base || !columns_hash.include?(inheritance_column) end end

new(attributes = nil, &block)Link

Determines if one of the attributes passed in is the inheritance column, and if the inheritance column is attr accessible, it initializes an instance of the given subclass instead of the base class.

Source: show | on GitHub

def new(attributes = nil, &block) if abstract_class? || self == Base raise NotImplementedError, "#{self} is an abstract class and cannot be instantiated." end

if _has_attribute?(inheritance_column) subclass = subclass_from_attributes(attributes)

if subclass.nil? && scope_attributes = current_scope&.scope_for_create
  subclass = subclass_from_attributes(scope_attributes)
end

if subclass.nil? && base_class?
  subclass = subclass_from_attributes(column_defaults)
end

end

if subclass && subclass != self subclass.new(attributes, &block) else super end end

Returns the class for the provided name.

It is used to find the class correspondent to the value stored in the polymorphic type column.

Source: show | on GitHub

def polymorphic_class_for(name) if store_full_class_name name.constantize else compute_type(name) end end

Returns the value to be stored in the polymorphic type column for Polymorphic Associations.

Source: show | on GitHub

def polymorphic_name store_full_class_name ? base_class.name : base_class.name.demodulize end

Sets the application record class for Active Record

This is useful if your application uses a different class than ApplicationRecord for your primary abstract class. This class will share a database connection with Active Record. It is the class that connects to your primary database.

Source: show | on GitHub

def primary_abstract_class if ActiveRecord.application_record_class && ActiveRecord.application_record_class.name != name raise ArgumentError, "The primary_abstract_class is already set to #{ActiveRecord.application_record_class.inspect}. There can only be one primary_abstract_class in an application." end

self.abstract_class = true ActiveRecord.application_record_class = self end

Returns the class for the provided type_name.

It is used to find the class correspondent to the value stored in the inheritance column.

Source: show | on GitHub

def sti_class_for(type_name) if store_full_sti_class && store_full_class_name type_name.constantize else compute_type(type_name) end rescue NameError raise SubclassNotFound, "The single-table inheritance mechanism failed to locate the subclass: '#{type_name}'. "
"This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. "
"Please rename this column if you didn't intend it to be used for storing the inheritance class "
"or overwrite #{name}.inheritance_column to use another column for that information. "
"If you wish to disable single-table inheritance for #{name} set "
"#{name}.inheritance_column to nil" end

Returns the value to be stored in the inheritance column for STI.

Source: show | on GitHub

def sti_name store_full_sti_class && store_full_class_name ? name : name.demodulize end

Instance Protected methods

Returns the class type of the record using the current module as a prefix. So descendants of MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.

Source: show | on GitHub

def compute_type(type_name) if type_name.start_with?("::")

type_name.constantize

else type_candidate = @_type_candidates_cache[type_name] if type_candidate && type_constant = type_candidate.safe_constantize return type_constant end

candidates = []
name.scan(/::|$/) { candidates.unshift "#{$`}::#{type_name}" }
candidates << type_name

candidates.each do |candidate|
  constant = candidate.safe_constantize
  if candidate == constant.to_s
    @_type_candidates_cache[type_name] = candidate
    return constant
  end
end

raise NameError.new("uninitialized constant #{candidates.first}", candidates.first)

end end