两个belongs_to关联的相同模型

发布于 2024-10-22 10:07:25 字数 879 浏览 8 评论 0原文

我有一个模型 PointOfContact，其中 has_many Systems。从Systems方面，我想将PointOfContact标识为technical_manager或project_manager（或两者）。同时仍然只在数据库中保留 PointOfContact 1 次。

我的尝试如下：

class System < ActiveRecord::Base
  belongs_to :project_manager, :class_name => 'PointOfContact'
  belongs_to :technical_manager, :class_name => 'PointOfContact'
end

class PointOfContact < ActiveRecord::Base
  has_many :systems
end

当我运行我的规范时（示例如下），我可以正确创建 System 联系点关联。然而，PointOfContact 不知道它与 System 的关联。这是为什么？

@sys = System.create
@tm = PointOfContact.create
@pm = PointOfContact.create

@sys.project_manager = @pm
@sys.technical_manager = @tm

@pm.systems.should have(1).items #> expected 1 items, got 0

原文

I have an model PointOfContact which has_many Systems. From the Systems side I want to identify the PointOfContact as either the technical_manager or project_manager (or both). While still only keeping the PointOfContact 1 time in the DB.

My attempt follows:

class System < ActiveRecord::Base
  belongs_to :project_manager, :class_name => 'PointOfContact'
  belongs_to :technical_manager, :class_name => 'PointOfContact'
end

class PointOfContact < ActiveRecord::Base
  has_many :systems
end

When I run my specs (example follows) I can correctly create the System point of contact associations. However, the PointOfContact is not aware of its association with System. Why is that?

@sys = System.create
@tm = PointOfContact.create
@pm = PointOfContact.create

@sys.project_manager = @pm
@sys.technical_manager = @tm

@pm.systems.should have(1).items #> expected 1 items, got 0

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注定孤独终老 2024-10-29 10:07:25

感谢 RailsForum.com 上的 jamesw：两个属于关联的相同模型已找到解决方案。

class System < ActiveRecord::Base
  belongs_to :project_manager, :class_name => 'PointOfContact', :foreign_key => 'project_manager_id'
  belongs_to :technical_manager, :class_name => 'PointOfContact', :foreign_key => 'technical_manager_id'
end

class PointOfContact < ActiveRecord::Base
  has_many :project_managed_systems, :class_name => 'System', :foreign_key => 'project_manager_id'
  has_many :technical_managed_systems, :class_name => 'System', :foreign_key => 'technical_manager_id'
end

Thanks to jamesw over at RailsForum.com: Same Model for Two belongs_to Associations a solution has been found.

class System < ActiveRecord::Base
  belongs_to :project_manager, :class_name => 'PointOfContact', :foreign_key => 'project_manager_id'
  belongs_to :technical_manager, :class_name => 'PointOfContact', :foreign_key => 'technical_manager_id'
end

class PointOfContact < ActiveRecord::Base
  has_many :project_managed_systems, :class_name => 'System', :foreign_key => 'project_manager_id'
  has_many :technical_managed_systems, :class_name => 'System', :foreign_key => 'technical_manager_id'
end

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少女情怀诗 2024-10-29 10:07:25

来自 Rails 文档：

带注释的示例：

# Employee class with two Employee associations
class Employee < ApplicationRecord

  # Employees I manage
  has_many :subordinates, class_name: "Employee",
                          foreign_key: "manager_id"

  # Employee that manages me
  # NOTE: with :manager reference name, foreign_key defaults to "manager_id",
  # hence it is not needed as above. Favor "convention over configuration".
  belongs_to :manager, class_name: "Employee"
end

From the Rails documentation:

Annotated example:

# Employee class with two Employee associations
class Employee < ApplicationRecord

  # Employees I manage
  has_many :subordinates, class_name: "Employee",
                          foreign_key: "manager_id"

  # Employee that manages me
  # NOTE: with :manager reference name, foreign_key defaults to "manager_id",
  # hence it is not needed as above. Favor "convention over configuration".
  belongs_to :manager, class_name: "Employee"
end

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