rails中belongs_to中model验证问题

问题描述:

在使用rails5开发时,追加了一个table并配置好belongs_to关系,随后在创建页面,提示table_id 不能为空。检查之后并没有验证,排查之后发现原来是rails5中,默认设置了这一验证,可同过optional属性设置掉。

参考链接:https://www.bigbinary.com/blog/rails-5-makes-belong-to-association-required-by-default

只为自己做笔记,方便查阅复习。

In Rails 5, whenever we define a belongs_to association, it is required to have the associated record present by default after this change.

It triggers validation error if associated record is not present.

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class User < ApplicationRecord
end
 
class Post < ApplicationRecord
  belongs_to :user
end
 
post = Post.create(title: 'Hi')
=> <Post id: nil, title: "Hi", user_id: nil, created_at: nil, updated_at: nil>
 
post.errors.full_messages.to_sentence
=> "User must exist"

As we can see, we can't create any post record without having an associated user record.

How to achieve this behavior before Rails 5

In Rails 4.x world To add validation on belongs_to association, we need to add option required: true .

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class User < ApplicationRecord
end
 
class Post < ApplicationRecord
  belongs_to :user, required: true
end
 
post = Post.create(title: 'Hi')
=> <Post id: nil, title: "Hi", user_id: nil, created_at: nil, updated_at: nil>
 
post.errors.full_messages.to_sentence
=> "User must exist"

  

By default, required option is set to false.

Opting out of this default behavior in Rails 5

We can pass optional: true to the belongs_to association which would remove this validation check.

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class Post < ApplicationRecord
  belongs_to :user, optional: true
end
 
post = Post.create(title: 'Hi')
=> <Post id: 2, title: "Hi", user_id: nil>

But, what if we do not need this behavior anywhere in our entire application and not just a single model?

Opting out of this default behavior for the entire application

New Rails 5 application comes with an initializer named new_framework_defaults.rb.

When upgrading from older version of Rails to Rails 5, we can add this initializer by running bin/rails app:update task.

This initializer has config named Rails.application.config.active_record.belongs_to_required_by_default = true

For new Rails 5 application the value is set to true but for old applications, this is set to false by default.

We can turn off this behavior by keeping the value to false.

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Rails.application.config.active_record.belongs_to_required_by_default = false
 
class Post < ApplicationRecord
  belongs_to :user
end
 
post = Post.create(title: 'Hi')
=> <Post id: 3, title: "Hi", user_id: nil, created_at: "2016-02-11 12:36:05", updated_at: "2016-02-11 12:36:05">

  

 

  

 

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