Rails5.0.0.beta3中accepts_nested_attributes_for的问题，-api选项

Question

我正在使用 Rails 5.0.0.beta3，使用 -app 选项构建一个仅限 API 的应用程序 新，我在accepts_nested_attributes_for时遇到了问题。

在我的应用程序中，创建(或新建，然后保存！)失败，并显示一条消息，提示父对象必须存在。

为了进行测试，我开发了一个新的应用程序，并在ANAF文档中对成员和帖子使用了测试用例:

class Member < ApplicationRecord  
  has_many :posts  
  accepts_nested_attributes_for :posts  
end  

和

class Post < ApplicationRecord
 belongs_to :member
end

（这些类定义是由Rails脚手架生成器生成的，所以继承自应用记录，而不是ActiveRecord::Ba，但在这篇文章中，这并不重要。）

创建并运行这些已定义且匹配的迁移后，我启动一个 Rails 控制台并按照文档中的步骤操作：

params = { member: {
name: 'joe', posts_attributes: [
    { title: 'Kari, the awesome Ruby documentation browser!' },
    { title: 'The egalitarian assumption of the modern citizen' },
    { title: '', _destroy: '1' } # this will be ignored
]}}  

{:member=>{:name=>"joe", :posts_attributes=>[{:title=>"Kari, the awesome Ruby documentation browser!"}, {:title=>"The egalitarian assumption of the modern citizen"}, {:title=>"", :_destroy=>"1"}]}}

然后：

>> member = Member.create(params[:member])
 (0.2ms)  BEGIN
 (0.4ms)  ROLLBACK
#<Member id: nil, name: "joe", created_at: nil, updated_at: nil>

没有喜悦！

当我将创建拆分为新的，然后保存！，我得到了同样的结果，但有一个更清晰的错误：

>> member = Member.new(params[:member])  
#<Member id: nil, name: "joe", created_at: nil, updated_at: nil>

会员.保存！< br >(15.0 ms)BEGIN active record::record invalid:验证失败:Posts成员必须< br >来自/Users/pauldavis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/validations . Rb:78:in < code > raise _ validation _ error ' < br > from/Users/Paul Davis/。' rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/validations . Rb:50:in save！'来自/Users/pauldavis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/attribute _ methods/dirty . Rb:30:in < code > save！来自/Users/pauldavis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/transactions . Rb:324:in 块in save！'来自/Users/pauldavis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/transactions . Rb:395:in < code > block in with _ transaction _ returning _ status ' from/Users/Paul Davis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/connection _ adapters/abstract/database _ statements . Rb:233:in block in transaction ' from/Users/Paul Davis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/connection _ adapters/abstract/transaction . Rb:189:in < code > within _ new _ transaction ' from/Users/Paul Davis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/connection _ adapters/abstract/database _ statements . Rb:233:in transaction ' from/Users/Paul Davis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/transactions . Rb:211:in < code > transaction ' from/Users/Paul Davis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/transactions . Rb:392:in with _ transaction _ returning _ status ' from/Users/Paul Davis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/transactions . Rb:324:in < code >保存！来自/Users/pauldavis/。' rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/active record/lib/active _ record/suppressor . Rb:45:in save！'发自(irb):14发自/Users/pauldavis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/rail ties/lib/rails/commands/console . Rb:65:in < code > start ' from/Users/Paul Davis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/rail ties/lib/rails/commands/console _ helper . Rb:9:in start '(0.2 ms)从/Users/pauldavis/回滚。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/rail ties/lib/rails/commands/commands _ tasks . Rb:78:in < code > console ' from/Users/Paul Davis/。' rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/rail ties/lib/rails/commands/commands _ tasks . Rb:49:in run _ command！'来自/Users/pauldavis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/rails-b 785064958 f 9/rail ties/lib/rails/command . Rb:20:in < code > run ' from/Users/Paul Davis/。rvm/gems/ruby-2 . 2 . 4/bundler/gems/Rails-b 785064958 f 9/rail ties/lib/Rails/commands . Rb:18:in ' from/Users/pauldavis/Documents/Projects/Active/Rails/好奇/doko/m . 0/test _ anaf/bin/Rails:9:in < code > require ' from/Users/pauldavis/Documents/Projects/Active/Rails/好奇/doko/m . 0/test _ anaf/bin/Rails:9

关于为什么文档中的此示例代码可以工作的任何想法？我的环境会不会有问题？-api 选项会破坏 ActiveRecord 中的某些内容吗？顺便说一句，我正在使用PostgreSQL

谢谢！

Answer 1

我也有同样的问题，我在https://github.com/rails/rails/issues/18233找到了解决办法

只需添加

class Post < ApplicationRecord
belongs_to :member, required: false
end

Rails 5中的accepts_nested_attributes_for似乎有问题，因此您需要将要求：假添加到您的子模型中。

Answer 2

这是一个报告为rails#25198的回归。如前所述，您可以使用inverse_of作为解决方法。

计划在5.0.1中修复。

Answer 3

我也遇到了同样的问题。
似乎规范已经从Rails 5更改。
通过放置选项，和之前的操作相同。

belongs_to应默认为required:true#18233

class Post < ApplicationRecord
  belongs_to :member, optional: true
end

这是我笨拙的可能会说英语，但。。。