Class: ActiveRecord::Reflection::ThroughReflection

Inherits:
AbstractReflection show all
Defined in:
lib/active_record/reflection.rb

Overview

Holds all the metadata about a :through association as it was specified in the Active Record class.

Instance Method Summary collapse

Methods inherited from AbstractReflection

#alias_candidate, #build_association, #build_scope, #chain, #check_validity_of_inverse!, #class_name, #counter_cache_column, #counter_must_be_updated_by_has_many?, #get_join_keys, #has_cached_counter?, #inverse_of, #inverse_updates_counter_in_memory?, #inverse_which_updates_counter_cache, #join_foreign_key, #join_keys, #join_primary_key, #join_scope, #klass_join_scope, #table_name

Constructor Details

#initialize(delegate_reflection) ⇒ ThroughReflection

Returns a new instance of ThroughReflection.



756
757
758
759
760
 
# File 'lib/active_record/reflection.rb', line 756

def initialize(delegate_reflection)
  @delegate_reflection = delegate_reflection
  @klass = delegate_reflection.options[:anonymous_class]
  @source_reflection_name = delegate_reflection.options[:source]
end

Instance Method Details

#add_as_polymorphic_through(reflection, seed) ⇒ Object 



958
959
960
 
# File 'lib/active_record/reflection.rb', line 958

def add_as_polymorphic_through(reflection, seed)
  collect_join_reflections(seed + [PolymorphicReflection.new(self, reflection)])
end

#add_as_source(seed) ⇒ Object 



954
955
956
 
# File 'lib/active_record/reflection.rb', line 954

def add_as_source(seed)
  collect_join_reflections seed
end

#add_as_through(seed) ⇒ Object 



962
963
964
 
# File 'lib/active_record/reflection.rb', line 962

def add_as_through(seed)
  collect_join_reflections(seed + [self])
end

#association_primary_key(klass = nil) ⇒ Object

We want to use the klass from this reflection, rather than just delegate straight to the source_reflection, because the source_reflection may be polymorphic. We still need to respect the source_reflection's :primary_key option, though.



858
859
860
861
862
 
# File 'lib/active_record/reflection.rb', line 858

def association_primary_key(klass = nil)
  # Get the "actual" source reflection if the immediate source reflection has a
  # source reflection itself
  actual_source_reflection.options[:primary_key] || primary_key(klass || self.klass)
end

#check_validity! ⇒ Object 



908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
 
# File 'lib/active_record/reflection.rb', line 908

def check_validity!
  if through_reflection.nil?
    raise HasManyThroughAssociationNotFoundError.new(active_record.name, self)
  end

  if through_reflection.polymorphic?
    if has_one?
      raise HasOneAssociationPolymorphicThroughError.new(active_record.name, self)
    else
      raise HasManyThroughAssociationPolymorphicThroughError.new(active_record.name, self)
    end
  end

  if source_reflection.nil?
    raise HasManyThroughSourceAssociationNotFoundError.new(self)
  end

  if options[:source_type] && !source_reflection.polymorphic?
    raise HasManyThroughAssociationPointlessSourceTypeError.new(active_record.name, self, source_reflection)
  end

  if source_reflection.polymorphic? && options[:source_type].nil?
    raise HasManyThroughAssociationPolymorphicSourceError.new(active_record.name, self, source_reflection)
  end

  if has_one? && through_reflection.collection?
    raise HasOneThroughCantAssociateThroughCollection.new(active_record.name, self, through_reflection)
  end

  if parent_reflection.nil?
    reflections = active_record.reflections.keys.map(&:to_sym)

    if reflections.index(through_reflection.name) > reflections.index(name)
      raise HasManyThroughOrderError.new(active_record.name, self, through_reflection)
    end
  end

  check_validity_of_inverse!
end

#clear_association_scope_cache ⇒ Object

This is for clearing cache on the reflection. Useful for tests that need to compare SQL queries on associations.



830
831
832
833
834
 
# File 'lib/active_record/reflection.rb', line 830

def clear_association_scope_cache # :nodoc:
  delegate_reflection.clear_association_scope_cache
  source_reflection.clear_association_scope_cache
  through_reflection.clear_association_scope_cache
end

#collect_join_chain ⇒ Object

Returns an array of reflections which are involved in this association. Each item in the array corresponds to a table which will be part of the query for this association.

The chain is built by recursively calling #chain on the source reflection and the through reflection. The base case for the recursion is a normal association, which just returns

self

as its #chain.

class Post < ActiveRecord::Base
  has_many :taggings
  has_many :tags, through: :taggings
end

tags_reflection = Post.reflect_on_association(:tags)
tags_reflection.chain
# => [<ActiveRecord::Reflection::ThroughReflection: @delegate_reflection=#<ActiveRecord::Reflection::HasManyReflection: @name=:tags...>,
      <ActiveRecord::Reflection::HasManyReflection: @name=:taggings, @options={}, @active_record=Post>]



824
825
826
 
# File 'lib/active_record/reflection.rb', line 824

def collect_join_chain
  collect_join_reflections [self]
end

#constraints ⇒ Object 



948
949
950
951
952
 
# File 'lib/active_record/reflection.rb', line 948

def constraints
  scope_chain = source_reflection.constraints
  scope_chain << scope if scope
  scope_chain
end

#has_scope? ⇒ Boolean

Returns:

  • (Boolean) 


844
845
846
847
848
 
# File 'lib/active_record/reflection.rb', line 844

def has_scope?
  scope || options[:source_type] ||
    source_reflection.has_scope? ||
    through_reflection.has_scope?
end

#join_scopes(table, predicate_builder, klass = self.klass) ⇒ Object

:nodoc:



840
841
842
 
# File 'lib/active_record/reflection.rb', line 840

def join_scopes(table, predicate_builder, klass = self.klass) # :nodoc:
  source_reflection.join_scopes(table, predicate_builder, klass) + super
end

#klass ⇒ Object 



766
767
768
 
# File 'lib/active_record/reflection.rb', line 766

def klass
  @klass ||= delegate_reflection.compute_class(class_name)
end

#nested? ⇒ Boolean

A through association is nested if there would be more than one join table

Returns:

  • (Boolean) 


851
852
853
 
# File 'lib/active_record/reflection.rb', line 851

def nested?
  source_reflection.through_reflection? || through_reflection.through_reflection?
end

#scopes ⇒ Object 



836
837
838
 
# File 'lib/active_record/reflection.rb', line 836

def scopes
  source_reflection.scopes + super
end

#source_options ⇒ Object 



900
901
902
 
# File 'lib/active_record/reflection.rb', line 900

def source_options
  source_reflection.options
end

#source_reflection ⇒ Object

Returns the source of the through reflection. It checks both a singularized and pluralized form for :belongs_to or :has_many.

class Post < ActiveRecord::Base
  has_many :taggings
  has_many :tags, through: :taggings
end

class Tagging < ActiveRecord::Base
  belongs_to :post
  belongs_to :tag
end

tags_reflection = Post.reflect_on_association(:tags)
tags_reflection.source_reflection
# => <ActiveRecord::Reflection::BelongsToReflection: @name=:tag, @active_record=Tagging, @plural_name="tags">



787
788
789
 
# File 'lib/active_record/reflection.rb', line 787

def source_reflection
  through_reflection.klass._reflect_on_association(source_reflection_name)
end

#source_reflection_name ⇒ Object

:nodoc:



879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
 
# File 'lib/active_record/reflection.rb', line 879

def source_reflection_name # :nodoc:
  return @source_reflection_name if @source_reflection_name

  names = [name.to_s.singularize, name].collect(&:to_sym).uniq
  names = names.find_all { |n|
    through_reflection.klass._reflect_on_association(n)
  }

  if names.length > 1
    raise AmbiguousSourceReflectionForThroughAssociation.new(
      active_record.name,
      macro,
      name,
      options,
      source_reflection_names
    )
  end

  @source_reflection_name = names.first
end

#source_reflection_names ⇒ Object

Gets an array of possible :through source reflection names in both singular and plural form.

class Post < ActiveRecord::Base
  has_many :taggings
  has_many :tags, through: :taggings
end

tags_reflection = Post.reflect_on_association(:tags)
tags_reflection.source_reflection_names
# => [:tag, :tags]



875
876
877
 
# File 'lib/active_record/reflection.rb', line 875

def source_reflection_names
  options[:source] ? [options[:source]] : [name.to_s.singularize, name].uniq
end

#through_options ⇒ Object 



904
905
906
 
# File 'lib/active_record/reflection.rb', line 904

def through_options
  through_reflection.options
end

#through_reflection ⇒ Object

Returns the AssociationReflection object specified in the :through option of a HasManyThrough or HasOneThrough association.

class Post < ActiveRecord::Base
  has_many :taggings
  has_many :tags, through: :taggings
end

tags_reflection = Post.reflect_on_association(:tags)
tags_reflection.through_reflection
# => <ActiveRecord::Reflection::HasManyReflection: @name=:taggings, @active_record=Post, @plural_name="taggings">



803
804
805
 
# File 'lib/active_record/reflection.rb', line 803

def through_reflection
  active_record._reflect_on_association(options[:through])
end

#through_reflection? ⇒ Boolean

Returns:

  • (Boolean) 


762
763
764
 
# File 'lib/active_record/reflection.rb', line 762

def through_reflection?
  true
end