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_join_constraint, #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.


758
759
760
761
762
# File 'lib/active_record/reflection.rb', line 758

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


960
961
962
# File 'lib/active_record/reflection.rb', line 960

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

#add_as_source(seed) ⇒ Object


956
957
958
# File 'lib/active_record/reflection.rb', line 956

def add_as_source(seed)
  collect_join_reflections seed
end

#add_as_through(seed) ⇒ Object


964
965
966
# File 'lib/active_record/reflection.rb', line 964

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.


860
861
862
863
864
# File 'lib/active_record/reflection.rb', line 860

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


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
947
948
# File 'lib/active_record/reflection.rb', line 910

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_cacheObject

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


832
833
834
835
836
# File 'lib/active_record/reflection.rb', line 832

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_chainObject

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>]

826
827
828
# File 'lib/active_record/reflection.rb', line 826

def collect_join_chain
  collect_join_reflections [self]
end

#constraintsObject


950
951
952
953
954
# File 'lib/active_record/reflection.rb', line 950

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

#has_scope?Boolean

Returns:

  • (Boolean)

846
847
848
849
850
# File 'lib/active_record/reflection.rb', line 846

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

#join_scopes(table, predicate_builder) ⇒ Object

:nodoc:


842
843
844
# File 'lib/active_record/reflection.rb', line 842

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

#klassObject


768
769
770
# File 'lib/active_record/reflection.rb', line 768

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)

853
854
855
# File 'lib/active_record/reflection.rb', line 853

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

#scopesObject


838
839
840
# File 'lib/active_record/reflection.rb', line 838

def scopes
  source_reflection.scopes + super
end

#source_optionsObject


902
903
904
# File 'lib/active_record/reflection.rb', line 902

def source_options
  source_reflection.options
end

#source_reflectionObject

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">

789
790
791
# File 'lib/active_record/reflection.rb', line 789

def source_reflection
  through_reflection.klass._reflect_on_association(source_reflection_name)
end

#source_reflection_nameObject

:nodoc:


881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
# File 'lib/active_record/reflection.rb', line 881

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_namesObject

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]

877
878
879
# File 'lib/active_record/reflection.rb', line 877

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

#through_optionsObject


906
907
908
# File 'lib/active_record/reflection.rb', line 906

def through_options
  through_reflection.options
end

#through_reflectionObject

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">

805
806
807
# File 'lib/active_record/reflection.rb', line 805

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

#through_reflection?Boolean

Returns:

  • (Boolean)

764
765
766
# File 'lib/active_record/reflection.rb', line 764

def through_reflection?
  true
end