Rails:has_many通过不正确返回带有命名空间的模型 [英] Rails: has_many through not returning correctly with namespaced models

问题描述

我有3个模型. Rom::Favorite，Rom::Card，User.我在创建User has_many rom_cards through rom_favorites

I have 3 models. Rom::Favorite, Rom::Card, User. I am having an issue creating the User has_many rom_cards through rom_favorites

这是我模型的相关部分

Rom :: Card

class Rom::Card < ActiveRecord::Base
    has_many :rom_favorites, class_name: "Rom::Favorite", foreign_key: "rom_card_id", dependent: :destroy

    self.table_name = "rom_cards"

end

用户

class User < ActiveRecord::Base
  # Setup accessible (or protected) attributes for your model
  attr_accessible :email, :password, :password_confirmation, :remember_me, :role

  has_many :rom_favorites, class_name: "Rom::Favorite", dependent: :destroy
  has_many :rom_cards, class_name: "Rom::Card", through: :rom_favorites, class_name: "Rom::Favorite"

end

Rom ::收藏夹

   class Rom::Favorite < ActiveRecord::Base
      attr_accessible :rom_card_id, :user_id

      belongs_to :user
      belongs_to :rom_card, class_name: "Rom::Card"

      validates :user, presence: true
      validates :rom_card, presence: true
      validates :rom_card_id, :uniqueness => {:scope => :user_id}

      self.table_name = "rom_favorites"

    end

关联附带的所有实用程序方法都可以使用

All of the utility methods that come along with associations work except

a = User.find(1)
a.rom_cards

调用a.rom_cards返回一个空数组，并且似乎正在运行此SQL查询

The call a.rom_cards returns an empty array and it seems to run this SQL query

SELECT "rom_favorites".* FROM "rom_favorites" INNER JOIN "rom_favorites" "rom_favorites_rom_cards_join" ON "rom_favorites"."id" = "rom_favorites_rom_cards_join"."rom_card_id" WHERE "rom_favorites_rom_cards_join"."user_id" = 1

我在SQL方面不强，但我认为这似乎是正确的.

I am not strong in SQL, but I think this seems correct.

我知道a.rom_cards应该返回2张卡片，因为a.rom_favorites返回2个收藏夹，并且这些收藏夹中存在card_id.

I know a.rom_cards should return 2 cards because a.rom_favorites returns 2 favorites, and in those favorites are card_id's that exist.

应允许rom_cards的呼叫如下

has_many :rom_cards, class_name: "Rom::Card", through: :rom_favorites, class_name: "Rom::Favorite"

我觉得这个问题与以下事实有关:它试图通过收藏夹查找用户"卡片，并且正在寻找card_id(因为我指定了Rom :: Card类)而不是rom_card_id.但是我可能是错的，不是很确定.

I feel like the issue has something to do with the fact that it is trying to find the Users cards through favorites and it is looking for card_id (because I specified the class Rom::Card) instead of rom_card_id. But I could be wrong, not exactly sure.

推荐答案

您正在复制关联哈希中的键class_name.无需编写class_name: "Rom::Favorite"，因为使用through: :rom_favorites它将使用has_many :rom_favorites的配置选项.

You are duplicating the key class_name in the association hash. There is no need to write class_name: "Rom::Favorite" because by using through: :rom_favorites it will use the configuration options of has_many :rom_favorites.

尝试:

has_many :rom_cards, class_name: "Rom::Card", through: :rom_favorites

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