Rails N + 1 lorsque vous faites référence au même modèle deux fois

Question

J'ai 2 modèles:

class User < ActiveRecord::Base 

end 

class Message < ActiveRecord::Base 
    has_one :sender, :class_name => 'User' 
    has_one :recipient, :class_name => 'User' 
end 

et je veux obtenir tous les messages qu'un utilisateur REÇU donc en messages_controller.rb j'ai:

def messages_to_user 
    messages = Message.where(recipient_id: current_user.id) 

    respond_with messages 
    end 

ce service fonctionne, mais dans le journal que je peux voir N + 1 question classique:

Started GET "/messages_to_user" for 127.0.0.1 at 2017-01-22 15:35:01 +0200 
Processing by MessageController#user as */* 
    User Load (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? ORDER BY "users"."id" ASC LIMIT 1 [["id", 2]] 
    Message Load (0.0ms) SELECT "messages".* FROM "messages" WHERE "messages"."recipient_id" = ? [["recipient_id", 2]] 
[active_model_serializers] User Load (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 2]] 
[active_model_serializers] Rendered ActiveModel::Serializer::CollectionSerializer with ActiveModelSerializers::Adapter::Attributes (42.01ms) 
Completed 200 OK in 217ms (Views: 63.0ms | ActiveRecord: 3.0ms) 

donc j'ai essayé de résoudre en ajoutant includes:

def messages_to_user 
    messages = Message.includes(:recipient).where(recipient_id: current_user.id) 

    respond_with messages 
    end 

Mais j'obtiens l'erreur suivante:

SQLite3::SQLException: no such column: users.message_id: SELECT "users".* FROM "users" WHERE "users"."message_id" IN ('1', '2', '3', '4', '5', '6', '7', '8', '9') 

Comment il peut être fixé? Je veux retourner une collection de messages - pas un utilisateur et un ensemble de messages à l'intérieur de l'utilisateur. mais sans le N + 1 problème

EDIT

La connexion entre les 2 modèles se fait via la table des messages, voici la migration (champs expéditeur, destinataire), donc j'ai besoin du users.message_id dans users . en outre, n'importe quel utilisateur peut envoyer/recevoir plusieurs messages, peut-être que ma mise en œuvre ne reflète pas cela? comment cela devrait-il être fait?

est ici la migration Messages:

class CreateMessages < ActiveRecord::Migration 
    def change 
    create_table :messasges do |t| 
     t.string :title 
     t.references :sender, index: true, foreign_key: true 
     t.references :recipient, index: true, foreign_key: true 
     t.string :content 
     t.timestamps null: false 
    end 
    end 
end 

Answer 1

Essayez

messages = Message.includes(:recipient).references(:recipient).where(recipient_id: current_user.id)