将 has_many 和 :belongs_to 转换为 has_many :through

发布于 2024-09-13 08:48:24 字数 1123 浏览 10 评论 0原文

我当前有一个关联，其中：

Group :has_many Members 和 Employee :belongs_to Group

但现在我希望一个 Employee 也与多个组关联。

为此，我正在考虑制作：

groupizations group_id:integerEmployee_id:integercreated_at:datetime

这将更改 Employee 和 Group 模型：

class Groupizations < ActiveRecord::Base
   belongs_to  :employee
   belongs_to  :group
end

class Group < ActiveRecord::Base
   has_many    :groupizations
   has_many    :employees, :through => categorizaitons
end

class Employee < ActiveRecord::Base
   has_many    :groupizations
   has_many    :groups, :through => categorizaitons
end

我从多对多上的 Railscasts 剧集。我唯一感到困惑的是，现在我使用以下代码创建了一个新员工：

  def create
    @employee = Employee.new(params[:employee])
    if @employee.save
      flash[:notice] = "Successfully created employee."
      redirect_to @employee
    else
      render :action => 'new'
    end
  end

此代码将如何更改？我现在需要同时将数据添加到分组中吗？

原文

I have a current association where:

Group :has_many Employees and Employee :belongs_to Group

but now I want an Employee to be associated to many Groups as well.

For this purpose I am thinking of making:

groupizations group_id:integer employee_id:integer created_at:datetime

This will change Employee and Group models:

class Groupizations < ActiveRecord::Base
   belongs_to  :employee
   belongs_to  :group
end

class Group < ActiveRecord::Base
   has_many    :groupizations
   has_many    :employees, :through => categorizaitons
end

class Employee < ActiveRecord::Base
   has_many    :groupizations
   has_many    :groups, :through => categorizaitons
end

I understand all of this from railscasts episode on Many-to-Many. Only thing I am confused about is that right now I create a new Employee with following code:

  def create
    @employee = Employee.new(params[:employee])
    if @employee.save
      flash[:notice] = "Successfully created employee."
      redirect_to @employee
    else
      render :action => 'new'
    end
  end

how will this code change? Do I need to add data into groupizations at the same time now?

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半边脸i 2024-09-20 08:48:24

如果您想将员工添加到组中，您只需执行以下操作：

@employee.groups << @group

将自动创建您所称的Groupization 记录。如果您想在关联中放入一些元数据（当您想要指定这种关系的性质时，这很常见），您可以做一些更正式的事情：

@employee.groupizations.create(
  :group => group,
  :badge_number => 'F920'
)

由于连接模型通常在两个 ID 列上有一个唯一索引，因此请确保避免插入重复记录时可能发生的错误。这些看起来不同，具体取决于您的后端数据库，因此请进行相应的测试。您可以根据需要使用find_or_create。

If you want to add an Employee to a Group, you would only need to do:

@employee.groups << @group

The Groupization record, as you've called it, will be created automatically. If you want to put some meta-data in the association, which is common when you want to specify the nature of this relationship, you could do something more formal:

@employee.groupizations.create(
  :group => group,
  :badge_number => 'F920'
)

As join models typically have a unique index on the two ID columns, be sure to rescue from errors that may occur when inserting a duplicate record. These look different depending on your back-end DB, so test accordingly. You can use find_or_create as needed.

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