如何在HABTM中使用接受嵌套属性? [英] How can i use accepts nested attributes with the HABTM?

问题描述

我有两个模型User和Category.

I have two models User and Category.

    class User < ActiveRecord::Base
        has_and_belongs_to_many :categories
        accepts_nested_attributes_for :categories
    end

类似

    class Category < ActiveRecord::Base
        has_and_belongs_to_many :users
    end

我有一个要求，我必须将类别添加到类别表并添加引用，以便我可以获取与用户相关的类别，但是如果另一个用户输入相同的类别，则必须使用id代替创建一个新的.我该怎么办?

i have a requirement where i have to add the categories to the categories table and add the reference so that i can get the categories related to user but if another user enters the same category then i have to make use of the id instead of creating new one. How can i do it?

还有一件事是我必须添加一个引用该类别类型的属性类型.例如

And one more thing is i have to add an attribute type which refers that category type. for example

user1 ----> category1, category2
user2 ----> category2

这里的user1和user2具有category2，但是category2中的类型可能不同.那么我该如何维护呢?请帮我.我准备回答你的问题.

here user1 and user2 has category2 but the type in category2 may differ.So how can i maintain this? please help me. I am ready to answer your question.

推荐答案

必须使用has_many :through而不是HABTM来将字段type添加到关系中:

You must use has_many :through instead of HABTM to add the field type to the relationship:

class User < ActiveRecord::Base
  has_many :lines
  accepts_nested_attributes_for :lines
  has_many :categories, through: :lines
end

class Line < ActiveRecord::Base
  belongs_to :users
  belongs_to :category
end

class Category < ActiveRecord::Base
  has_many :lines
  has_many :users, through: :lines
end

将type属性添加到类Line.

ref: http://guides.rubyonrails.org/association_basics.html#the -通过关联有很多

您将需要两个具有轻松操作的控制器:users和categories

You will need two controllers with the restful actions: users and categories

然后，在您的用户表单中，如下所示:

Then, in your user form, something like:

<%= nested_form_for @user do |f| %>
...#user attributes
<%= f.fields_for :lines do |line| %>
<%= line.label :category %>
<%= line.collection_select(:category_id, Category.all, :id, :name , {include_blank: 'Select Category'} ) %>
<%= line.label :type %>
<%= line.text_field :type %>
...#the form continues

编辑-

类别独立于用户，用户独立于类别.

The category is independent of user, as well as user is independent of category.

关联类Line将通过category_id和user_id加入用户和类别:

The association class Line will join users and categories through the category_id and user_id:

________          _______________
| user |          |     line    |          ____________
|----- |          |-------------|          | category |
| id   |----------| user_id     |          |----------|
| name |1        *| category_id |----------| id       |
| email|          | type        |*        1| name     | 
|______|          |_____________|          |__________|

示例:

git hub: https://github.com/gabrielhilal/nested_form

heroku: http://nestedform.herokuapp.com/

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