ruby-on-rails - HABTM 2 表 2 种不同的关系

Question

我有一个服务类型表，其中包含几十个服务的 ID 和名称。

我有一个 Projects 表，其中必须有一个 Proposed Services 列表和一个 Accepted Services 列表。

我知道我会在两边都使用 HABTM，中间有一个 project_service_types 表。

当我在同一张表之间有 2 个不同的关系时，我不知道该怎么做。我怀疑它使用 :join_table 和 :associated_forign_key，但我无法让它在我的应用程序中工作。

谢谢。

Answer 1

我用HABTM解决了它......

class ServiceType < ActiveRecord::Base
  has_and_belongs_to_many :accepted_projects, :class_name => "Project", :join_table => :projects_accepted_types
  has_and_belongs_to_many :proposed_projects, :class_name => "Project", :join_table => :projects_proposed_types
end

class Project < ActiveRecord::Base
  has_and_belongs_to_many :accepted_types, :class_name => "ServiceType", :join_table => :projects_accepted_types
  has_and_belongs_to_many :proposed_types, :class_name => "ServiceType", :join_table => :projects_proposed_types
end

Answer 2

虽然您可以使用 habtm 解决这个问题，但您所说的是 has_many :through 的用例。您想在关系中附加一些信息。为此，您需要创建一个表示关系的连接模型。

最后，这使您可以将您的服务提案视为您领域中的一流“事物”。接受服务后，您只需更改状态即可。这也节省了一个连接。

移民

create_table :project_services do |t|
  t.references :project
  t.references :service_type
  t.string :status
end

楷模

class ProjectService < ActiveRecord::Base
  belongs_to :project
  belongs_to :service
end

class Project < ActiveRecord::Base
  has_many :project_services
  has_many :accepted_services, :through => :project_services,
    :conditions => { :status => 'accepted' }
  has_many :proposed_services, :through => :proposed_services,
    :conditions => { :status => 'proposed' }
end

class Service < ActiveRecord::Base
  has_many :project_services
  has_many :accepted_projects, :through => :project_services,
    :conditions => { :status => 'accepted' }
  has_many :proposed_projects, :through => :proposed_services,
    :conditions => { :status => 'proposed' }
end

Answer 3

为此，您可能希望使用 has_many :through 如下：

class ProposedService < ActiveRecord::Base
    belongs_to :project
    belongs_to :service_type

class AcceptedService < ActiveRecord::Base
    belongs_to :project
    belongs_to :service_type

class Projects < ActiveRecord::Base
    has_many :proposed_services
    has_many :accepted_services
    has_many :service_types, :through => :proposed_services
    has_many :service_types, :through => :accepted_services

class ServiceTypes < ActiveRecord::Base
    has_many :proposed_services
    has_many :accepted_services
    has_many :projects, :through => :proposed_services
    has_many :projects, :through => :accepted_services

这里的多对多部分：

http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html

更详细地解释了这一点。希望这可以帮助！