Question

$ rails -v
Rails 3.1.1
$ ruby -v
ruby 1.9.2p312 (2011-08-11 revision 32926) [i686-linux]

如果您想重现这个问题，请关注我：

首先，创建这三个模型（只是复制）：

#school.rb
class School
  include Mongoid::Document
  include Mongoid::Timestamps

  has_many :students

end

#student.rb
class Student
  include Mongoid::Document
  include Mongoid::Timestamps

  has_many :books
  belongs_to :school

  accepts_nested_attributes_for :books

end

#book.rb
class Book
  include Mongoid::Document
  include Mongoid::Timestamps

  field :name

  belongs_to :student

  validate :check

  def check
    # The calling for the 'school' method caused the issue
    self.student.school
  end

end

其次，运行您的控制台并粘贴：

ruby-1.9.2-head :001 > School.destroy_all;Student.destroy_all; Book.destroy_all; School.create
ruby-1.9.2-head :001 >  Student.create school_id: School.first.id, 'books_attributes' => {'1' => {'name' => 'I am a book'}}

然后，让我们看看发生了什么：

ruby-1.9.2-head :002 > Book.count
MONGODB xxx_development['$cmd'].find({"count"=>"books", "query"=>{}, "fields"=>nil})
=> 2

更重要的是，如果你将'student has_many books'关系设置为'autosave：true'：

class Student
 ......
 has_many :books, autosave: true
 ......
end

让我们看看会发生什么：

ruby-1.9.2-head :001 > School.destroy_all;Student.destroy_all; Book.destroy_all; School.create
ruby-1.9.2-head :001 >  Student.create school_id: School.first.id, 'books_attributes' => {'1' => {'name' => 'I am a book'}}
ruby-1.9.2-head :002 > Student.count
MONGODB xxx_development['$cmd'].find({"count"=>"students", "query"=>{}, "fields"=>nil})
 => 2 

ruby-1.9.2-head :004 > Student.all.to_a
MONGODB xxx_development['students'].find({})
 => [#<Student _id: 4f62a8341d41c81bc6000002, _type: nil, created_at: 2012-03-16 02:40:52 UTC, updated_at: 2012-03-16 02:40:52 UTC, school_id: BSON::ObjectId('4f62a8341d41c81bc6000001')>, #<Student _id: 4f62a8341d41c81bc6000003, _type: nil, created_at: 2012-03-16 02:40:52 UTC, updated_at: 2012-03-16 02:40:52 UTC, school_id: nil>] 

ruby-1.9.2-head :005 > Book.count
MONGODB xxx_development['$cmd'].find({"count"=>"books", "query"=>{}, "fields"=>nil})
 => 2
ruby-1.9.2-head :006 > Book.all.to_a
MONGODB xxx_development['books'].find({})
 => [#<Book _id: 4f62a8341d41c81bc6000003, _type: nil, created_at: 2012-03-16 02:40:52 UTC, updated_at: 2012-03-16 02:40:52 UTC, name: "I am a book", student_id: BSON::ObjectId('4f62a8341d41c81bc6000002')>, #<Book _id: 4f62a8341d41c81bc6000002, _type: nil, created_at: 2012-03-16 02:40:52 UTC, updated_at: 2012-03-16 02:40:52 UTC, name: nil, student_id: nil>]

这个错误让我疯狂。在图书验证方法中调用'school'时为什么有其他模型？

或者我做错了什么？

Answer 1

这里的代码很好，你没有做任何不正确的事 - 但是Mongoid在master或2.4.x上使用相同的代码没有问题。在这里查看我的建议，找到罪魁祸首：

https://github.com/mongoid/mongoid/issues/1826

它是Mongoid或Rails3的错误吗？这里有完整的代码，你可以重现奇怪的'bug'

1 个答案: