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Class: Mongoid::Association::Referenced::HasOneThrough::Eager

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::Mongoid::Association::Eager
Instance Chain:
self, ::Mongoid::Association::Eager
Inherits: Mongoid::Association::Eager
Defined in: lib/mongoid/association/referenced/has_one_through/eager.rb

Overview

Two-query eager preloader for has_one :through associations.

Class Method Summary

::Mongoid::Association::Eager - Inherited

.new

Instantiate the eager load class.

Instance Method Summary

::Mongoid::Association::Eager - Inherited

#run

Run the preloader.
#each_loaded_document_of_class

Retrieves the documents of the specified class, that have the foreign key included in the specified list of keys.
#prepare_criteria_for_loaded_documents

Prepares the criteria to retrieve the documents of the specified class, that have the foreign key included in the specified list of keys.
#shift_association

Shift the current association metadata.

Constructor Details

This class inherits a constructor from Mongoid::Association::Eager

Instance Method Details

#build_intermediate_to_target(intermediates, through_fk, source_assoc) (private)

[ GitHub ] 

  


# File 'lib/mongoid/association/referenced/has_one_through/eager.rb', line 34



def build_intermediate_to_target(intermediates, through_fk, source_assoc)
  if source_assoc.stores_foreign_key?
    # FK is on the intermediate (e.g. belongs_to :store => intermediate.store_id)
    source_fk_values = intermediates.filter_map { |i| i.public_send(source_assoc.foreign_key) }.uniq
    targets = source_assoc.klass.where(source_assoc.primary_key => { '$in' => source_fk_values }).to_a
    targets_by_key = targets.index_by { |t| t.public_send(source_assoc.primary_key) }
    intermediates.to_h do |i|
      [ i.public_send(through_fk), targets_by_key[i.public_send(source_assoc.foreign_key)] ]
    end
  else
    # FK is on the source (e.g. has_one :store => store.franchise_id)
    source_pk = source_assoc.primary_key
    intermediate_pks = intermediates.filter_map { |i| i.public_send(source_pk) }.uniq
    targets = source_assoc.klass.where(source_assoc.foreign_key => { '$in' => intermediate_pks }).to_a
    targets_by_fk = targets.index_by { |t| t.public_send(source_assoc.foreign_key) }
    intermediates.index_by { |i| i.public_send(through_fk) }.transform_values do |i|
      targets_by_fk[i.public_send(source_pk)]
    end
  end
end


  








  

    #group_by_key   (private)
  



  

    
Required by the base class contract. Not called by this preloader
because preload manages document traversal directly without using
the grouped_docs / keys_from_docs machinery from the base class.

  



  [ GitHub ]


  

  


# File 'lib/mongoid/association/referenced/has_one_through/eager.rb', line 58



def group_by_key
  @association.through_association.primary_key
end


  








  

    #preload   (private)
  

  [ GitHub ]


  

  


# File 'lib/mongoid/association/referenced/has_one_through/eager.rb', line 11



def preload
  @docs.each { |d| set_relation(d, nil) }

  through_assoc = @association.through_association
  source_assoc  = @association.source_association

  owner_pk   = through_assoc.primary_key
  through_fk = through_assoc.foreign_key

  owner_ids = @docs.filter_map { |d| d.public_send(owner_pk) }.uniq
  return if owner_ids.empty?

  intermediates = through_assoc.klass.where(through_fk => { '$in' => owner_ids }).to_a
  intermediate_to_target = build_intermediate_to_target(intermediates, through_fk, source_assoc)

  @docs.each do |doc|
    owner_key_val = doc.public_send(owner_pk)
    target = intermediate_to_target[owner_key_val]
    proxy = target ? HasOneThrough::Proxy.new(doc, target, @association) : nil
    doc.set_relation(@association.name, proxy) unless doc.blank?
  end
end