Rails 依赖: :destroy 导致 ArgumentError

Question

我的 Rails 应用程序中有一个用户模型，如下所示

class User < ActiveRecord::Base
  has_many :parts, dependent: :destroy
  has_many :assemblies, dependent: :destroy
  has_many :packages, dependent: :destroy
  has_many :manufacturers, dependent: :destroy
  //more code here
end

我在其他一些型号中也有dependent: :restrict。

当我在rails console 中运行以下命令时，我得到一个 ArgumentError：

u = User.first
u.parts

对u.parts 的调用会给出以下错误消息：

ArgumentError: Unknown key: dependent
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.2.1/lib/active_support/core_ext/hash/keys.rb:44:in `block in assert_valid_keys'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.2.1/lib/active_support/core_ext/hash/keys.rb:43:in `each_key'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.2.1/lib/active_support/core_ext/hash/keys.rb:43:in `assert_valid_keys'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/builder/association.rb:33:in `validate_options'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/builder/association.rb:24:in `build'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/builder/collection_association.rb:23:in `build'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/autosave_association.rb:139:in `build'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/builder/has_and_belongs_to_many.rb:8:in `build'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/builder/collection_association.rb:13:in `build'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations.rb:1600:in `has_and_belongs_to_many'
    from /home/david/code/PartSorter/app/models/part.rb:5:in `<class:Part>'
    from /home/david/code/PartSorter/app/models/part.rb:1:in `<top (required)>'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.2.1/lib/active_support/dependencies.rb:469:in `load'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.2.1/lib/active_support/dependencies.rb:469:in `block in load_file'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.2.1/lib/active_support/dependencies.rb:639:in `new_constants_in'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.2.1/lib/active_support/dependencies.rb:468:in `load_file'
... 12 levels...
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.2.1/lib/active_support/dependencies.rb:554:in `get'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.2.1/lib/active_support/dependencies.rb:588:in `constantize'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/inheritance.rb:111:in `block in compute_type'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/inheritance.rb:109:in `each'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/inheritance.rb:109:in `compute_type'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/reflection.rb:172:in `klass'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/association.rb:117:in `klass'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/association.rb:165:in `find_target?'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/collection_association.rb:332:in `load_target'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/collection_proxy.rb:44:in `load_target'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/associations/collection_proxy.rb:88:in `method_missing'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.1/lib/rails/commands/console.rb:47:in `start'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.1/lib/rails/commands/console.rb:8:in `start'
    from /home/david/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.1/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

我不确定为什么这不起作用 - 我按照指南 here 添加了 dependent 部分，但它不起作用。有什么想法吗？

编辑： part.rb的内容如下：

class Part < ActiveRecord::Base
  has_many :part_packages
  has_many :packages, through: :part_packages
  belongs_to :manufacturer
  has_and_belongs_to_many :assemblies, :dependent => :restrict
  belongs_to :user


  validates :name, :user_id, :presence => true

  def quantity
    @quantity = 0
    self.part_packages.each do |pp|
      @quantity += pp.quantity
    end
    @quantity
  end
end

Answer 1

:dependent 不是 has_and_belongs_to_many 的有效选项，因此您需要摆脱它并编写自己的解决方案来满足您的需求。

或者，您可能希望有一个显式连接模型，而不是使用has_and_belongs_to_many。这样您就可以使用:dependent 与连接模型建立关系。