在 Rails 协会中找不到命名的关联可能是拼写错误的问题 [英] association named not found perhaps misspelled issue in rails association

问题描述

这是我的控制器

@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

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

这是我的控制器输出:

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'

推荐答案

这是一个典型的拼写错误:

This is a typical typo error:

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

因为你定义了这样的关系(使用单数):

Because you defined the relation like this (using singular):

# Post model
belongs_to :customer

<小时>

一些需要了解的内容:

---

Some stuff to know:

• 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，总是使用关系的复数名称(实际上是表的名称，默认是复数形式的模型名称，但也可以手动设置)

• In the joins/includes method, always use the exact same name as the relation
• In the where clauses, always use the pluralized name of the relation (actually, the table's name, which is by default the model name in plural but can also be manually set)

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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