Module: Dagnabit::Link::NamedScopes

Defined in:
lib/dagnabit/link/named_scopes.rb

Overview

Adds named scopes to Link models.

This module provides two named scopes for finding links scoped by ancestor and descendant type. They were designed as support for node neighbor queries such as ancestors_of_type and descendants_as_type, but can be used on their own.

These links are imported into the generated transitive closure link model. See Dagnabit::Link::TransitiveClosureLinkModel for more information.

Supplied scopes

ancestor_type

Returns all links having a specified ancestor type.

descendant_type

Returns all links having a specified descendant type.

A note on type matching

Types are stored in links using ActiveRecord’s polymorphic association typing logic, and are matched using string matching. Therefore, subclass matching and namespacing aren’t provided.

To elaborate on this, let’s say you have the following model structure:

class Link < ActiveRecord::Base
  acts_as_dag_link
end

module Foo
  class Bar < ActiveRecord::Base
    ...
  end
end

A link linking Foo::Bars will record Foo::Bar as ancestor or descendant type, not just ‘Bar’. The following will therefore not work:

Link.ancestor_type('Bar')

You have to do:

Link.ancestor_type('Foo::Bar')

or, if you’d like to hide the details of deriving a full class name:

Link.ancestor_type(Bar.name)

Class Method Summary collapse

Class Method Details

.extended(base) ⇒ Object 



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# File 'lib/dagnabit/link/named_scopes.rb', line 54

def self.extended(base)
  base.send(:named_scope,
            :ancestor_type,
            lambda { |type| { :conditions => { :ancestor_type => type } } })

  base.send(:named_scope,
            :descendant_type,
            lambda { |type| { :conditions => { :descendant_type => type } } })
end