Class: ActiveRecord::CompositeKeyPreloader

Inherits:
Object
  • Object
show all
Defined in:
lib/active_record/composite_key_preloader.rb

Overview

Modified ActiveRecord::Associations::Preloader::Association

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(klass, owners, reflection, composite_key) ⇒ CompositeKeyPreloader

Returns a new instance of CompositeKeyPreloader.



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# File 'lib/active_record/composite_key_preloader.rb', line 21

def initialize(klass, owners, reflection, composite_key)
  @klass         = klass
  @owners        = owners
  @reflection    = reflection
  @preloaded_records = []
  @composite_key = composite_key
end

Class Method Details

.call(records, association, composite_key) ⇒ Object

The CompositeKeyPreloader does the same as default rails preloader ( ActiveRecord::Associations::Preloader ) The difference: CompositeKeyPreloader allows to reference another table by multiple columns

Parameters:

  • records (Array<ActiveModel>) —

    Collection of active record models

  • association (Symbol) —

    ActiveRecord model association name to preload

  • composite_key (Array<Symbol>) —

    Array of primary_keys, defines how association should be loaded. Default Rails implementation does not allow to specify composite key (multi-column key)



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# File 'lib/active_record/composite_key_preloader.rb', line 13

def self.call(records, association, composite_key)
  records_for_preload = records.reject { |record| record.association(association).loaded? }
  return if records_for_preload.blank?

  assoc = records.first.association(association)
  new(assoc.klass, records, assoc.reflection, composite_key).run
end

Instance Method Details

#run ⇒ Object 



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# File 'lib/active_record/composite_key_preloader.rb', line 29

def run
  records = load_records

  owners.each do |owner|
    owner_key = @composite_key.map { |key_name| owner[key_name] }
    associate_records_to_owner(owner, records[owner_key] || [])
  end
end