Twitter 喜欢在 Rails 中关注

Question

我在我的应用程序中关注了这个tutorial to create Twitter like following，但是，我的关注不是互惠的，事实上，对方根本没有关注用户。我的两个主要模型是User 和Stock。用户应该能够“关注”股票，但股票永远不会关注用户。

models/user.rb

class User < ActiveRecord::Base

  has_many :stock_relationships
  has_many :stocks, through: :stock_relationships, source: :user

  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable,
         :omniauthable, :omniauth_providers => [:facebook, :twitter, :linkedin, :google_oauth2]

   # stock following/unfollowing
   def follow_stock(stock)
     stock_relationships.create(stock_id: stock.id)
   end

   def unfollow_stock(stock)
     stock_relationships.find_by(stock_id: stock.id).destroy
   end

   def following_stock?(stock)
     stock_relationships.include?(stock.id)
   end

end

由于我的Stock 模型并不真正属于任何人，因此我在该模型中还没有任何东西：

models/stock.rb

class Stock < ActiveRecord::Base

end

为了跟踪 users 即 following 股票，我创建了另一个名为 StockRelationships 的模型：

models/stock_relationship.rb

class StockRelationship < ActiveRecord::Base
  belongs_to :user
end

我从控制台开始分配一个用户：

user = User.find(1)

我遇到了麻烦，因为在使用 following_stock? 方法时这似乎不起作用。

我可以创建一个stock_relationship：

pry(main)> user.follow_stock(stock)
   (0.2ms)  BEGIN
  SQL (2.2ms)  INSERT INTO "stock_relationships" ("stock_id", "user_id", "created_at", "updated_at") VALUES ($1, $2, $3, $4) RETURNING "id"  [["stock_id", 2], ["user_id", 1], ["created_at", "2016-07-12 01:01:00.552580"], ["updated_at", "2016-07-12 01:01:00.552580"]]
   (2.5ms)  COMMIT
=> #<StockRelationship:0x007ff0b960ba60
 id: 3,
 user_id: 1,
 stock_id: 2,
 created_at: Tue, 12 Jul 2016 01:01:00 UTC +00:00,
 updated_at: Tue, 12 Jul 2016 01:01:00 UTC +00:00>

我可以unfollow一只股票：

[10] pry(main)> user.unfollow_stock(stock)
  StockRelationship Load (0.4ms)  SELECT  "stock_relationships".* FROM "stock_relationships" WHERE "stock_relationships"."user_id" = $1 AND "stock_relationships"."stock_id" = $2 LIMIT 1  [["user_id", 1], ["stock_id", 2]]
   (0.1ms)  BEGIN
  SQL (0.3ms)  DELETE FROM "stock_relationships" WHERE "stock_relationships"."id" = $1  [["id", 3]]
   (1.5ms)  COMMIT
=> #<StockRelationship:0x007ff0b9d36a60
 id: 3,
 user_id: 1,
 stock_id: 2,
 created_at: Tue, 12 Jul 2016 01:01:00 UTC +00:00,
 updated_at: Tue, 12 Jul 2016 01:01:00 UTC +00:00>

但是，当我检查用户是否实际上是 following 股票时，我遇到了问题：

[13] pry(main)> user.following_stock?(stock)
=> false

应该返回true，因为用户实际上正在关注股票：

[15] pry(main)> StockRelationship.all
  StockRelationship Load (0.4ms)  SELECT "stock_relationships".* FROM "stock_relationships"
=> [#<StockRelationship:0x007ff0bfa00408
  id: 2,
  user_id: 1,
  stock_id: 1,
  created_at: Tue, 12 Jul 2016 00:32:55 UTC +00:00,
  updated_at: Tue, 12 Jul 2016 00:32:55 UTC +00:00>,
 #<StockRelationship:0x007ff0bfa002c8
  id: 4,
  user_id: 1,
  stock_id: 2,
  created_at: Tue, 12 Jul 2016 01:04:06 UTC +00:00,
  updated_at: Tue, 12 Jul 2016 01:04:06 UTC +00:00>]

我是否错误地实现了include?？我在模型中搞砸了什么吗？

提前致谢！

Answer 1

您的错误是数据类型比较问题。试试这个：

   def following_stock?(stock)
     # either use this
     stock_relationships.where(stock_id: stock.id).present?
     # OR
     stock_relationships.pluck(:stock_id).include?(stock.id)
   end

Answer 2

我现在不在一台可以测试的计算机上，但是查看您的代码，我偷偷怀疑原因可能是您的 has_many 关系中的source 声明。

在您的用户模型中，您有source: :user，我相信这会使关系在从关系的User 侧搜索时查找user_id 而不是stock_id。

您可能希望将其更改为 source: :stock，或者在您的情况下，由于模型名称和关系相同，您可以完全省略 source 声明。