Rails 5.0.0.beta3 中的accepts_nested_attributes_for 出现问题，-api 选项

Question

我正在使用 Rails 5.0.0.beta3，使用 rails new 上的 -app 选项构建一个仅限 API 的应用程序，但我在使用 accept_nested_attributes_for 时遇到问题。

在我的应用程序中，创建（或新建，然后保存！）具有嵌套属性的对象失败，并显示父父对象必须存在的消息。

为了测试，我制作了一个新应用程序，并仅使用了测试用例，其中包含ANAF documentation 中的成员和帖子：

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，因此继承自 ApplicationRecord，而不是 ActiveRecord::Base，但对于 this post，这并不重要。）

定义了这些类，并创建并运行了匹配的迁移，我启动了一个 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>

不开心！

当我将 create 拆分为 new，然后 save! 时，我得到了相同的结果，但错误更清晰：

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

member.save！
(15.0ms) 开始 ActiveRecord::RecordInvalid：验证失败：帖子成员必须存在
来自 /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/validations.rb:78:in raise_validation_error'
from /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/validations.rb:50:insave！ 来自 /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/attribute_methods/dirty.rb:30:in save!' from /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/transactions.rb:324:inblock in save！ 来自 /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/transactions.rb:395:in block in with_transaction_returning_status' from /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:233:inblock in transaction' 来自 /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb:189:in within_new_transaction' from /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:233:intransaction' 来自 /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/transactions.rb:211:in transaction' from /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/transactions.rb:392:inwith_transaction_returning_status' 来自 /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/transactions.rb:324:in save!' from /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/activerecord/lib/active_record/suppressor.rb:45:insave！ 来自 (irb):14 来自 /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/railties/lib/rails/commands/console.rb:65:in start' from /Users/pauldavis/.rvm/gems/ruby-2.2.4 /bundler/gems/rails-b785064958f9/railties/lib/rails/commands/console_helper.rb:9:instart' (0.2ms) 回滚 来自 /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/railties/lib/rails/commands/commands_tasks.rb:78:in console' from /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/railties/lib/rails/commands/commands_tasks.rb:49:inrun_command！ 来自 /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/railties/lib/rails/command.rb:20:in run' from /Users/pauldavis/.rvm/gems/ruby-2.2.4/bundler/gems/rails-b785064958f9/railties/lib/rails/commands.rb:18:in' 来自 /Users/pauldavis/Documents/Projects/Active/Rails/curious/doko/m.0/test_anaf/bin/rails:9:in require' from /Users/pauldavis/Documents/Projects/Active/Rails/curious/doko/m.0/test_anaf/bin/rails:9:in' 来自 -e:1:in load' from -e:1:in'

您对文档中的示例代码为何有效有任何想法吗？我的环境可能有问题吗？ -api 选项是否会破坏 ActiveRecord 中的某些内容？顺便说一句，我正在使用 PostgreSQL

谢谢！

Answer 1

我也遇到了同样的问题。
似乎规范已从 Rails 5 更改。
通过把选项，和前面一样的操作。

belongs_to should default to required: true #18233

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

我笨拙会说英语，但是……

Answer 2

这是一个报告为rails#25198 的回归。正如所指出的，您可以使用inverse_of 作为解决方法。

计划在 5.0.1 中修复。

Answer 3

我遇到了同样的问题，我在https://github.com/rails/rails/issues/18233找到了解决方案

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required: false 添加到您的子模型中。

Answer 4

我发现将inverse_of 选项添加到关联允许accepts_nested_attributes 工作。比猴子修补好，仍然允许验证关联

Answer 5

我在我的 Rails 5 beta 3 应用程序中也遇到了accepts_nested_attributes_for 的问题，并且似乎有问题。理想情况下，应该提交一个错误报告，但我们没有时间正确地完成它。我们有以下设置：

accepts_nested_attributes_for :attachments, allow_destroy: true

最终，我们不得不像这样对模型内部的方法进行猴子补丁：

  def attachments_attributes=(attributes)
    attributes.reject! do |_attachment|  
      if _attachment = Attachment.find(_attachment['id'])
        if _attachment.drop_id.nil?
          attachments << _attachment
          next true
        end
      end
      next false
    end
    # assign_nested_attributes_for_collection_association(:attachments, attributes)
  end

唯一的问题是带有assign_nested_attributes_for_collection_association 的最后一行（注释掉的行）有一些问题，但希望这能让您了解如何解决这个问题。