ruby-on-rails - Rails 协会中未找到名为关联的可能拼写错误的问题

Question

这是我的 Controller

@post = Post.joins(:customers).select("customers.*,posts.*").find params[:id]

我的帖子模型

belongs_to :customer

我的客户模型

has_many :posts

我收到错误为

Association named 'customers' was not found on Post; perhaps you misspelled it?

这是我的 Controller 输出:

Processing by PostsController#show as */*
  Parameters: {"id"=>"6"}
  Post Load (0.5ms)  SELECT "posts".* FROM "posts" WHERE "posts"."id" = $1 LIMIT 1  [["id", "6"]]
Completed 500 Internal Server Error in 113ms

ActiveRecord::ConfigurationError (Association named 'customers' was not found on Post; perhaps you misspelled it?):
  app/controllers/posts_controller.rb:16:in `show'

Answer 1

这是一个典型的拼写错误:

@post = Post.joins(:customers).select("customers.*,posts.*").find params[:id]
# should be:
@post = Post.joins(:customer).select("customers.*,posts.*").find params[:id]
                          #^^ no plural

因为您像这样定义了关系(使用单数):

# Post model
belongs_to :customer

<小时/>

一些需要知道的事情:

• 在 joins/includes 方法中，始终使用与关系完全相同的名称
• 在 where 子句中，始终使用关系的复数名称(实际上是表的名称，默认情况下是复数模型名称，但也可以手动设置)

示例:

# Consider these relations:
User has_many :posts
Post belongs_to :user

# Usage of joins/includes & where:
User.includes(:posts).where(posts: { name: 'BlogPost #1' })
                  #^            ^
Post.joins(:user).where(users: { name: 'Little Boby Table' })
              #^^           ^

<小时/>

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