Ruby-on-rails accepts_nested_attributes_for with has_many => :through 选项

accepts_nested_attributes_for with has_many => :through Options

提问by Andrew C

I have two models, links and tags, associated through a third, link_tags. The following code is in my Link model.

我有两个模型，链接和标签，通过第三个，link_tags 关联。以下代码在我的 Link 模型中。

Associations:

协会：

class Link < ActiveRecord::Base
  has_many :tags, :through => :link_tags
  has_many :link_tags

  accepts_nested_attributes_for :tags, :allow_destroy => :false, 
  :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } }
end

class Tag < ActiveRecord::Base
  has_many :links, :through => :link_tags
  has_many :link_tags
end

class LinkTag < ActiveRecord::Base
  belongs_to :link
  belongs_to :tag
end

links_controller Actions:

links_controller 操作：

  def new
    @link = @current_user.links.build
    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @link }
    end
  end

  def create
    @link = @current_user.links.build(params[:link])

    respond_to do |format|
      if @link.save
        flash[:notice] = 'Link was successfully created.'
        format.html { redirect_to links_path }
        format.xml  { render :xml => @link, :status => :created, :location => @link }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @link.errors, :status => :unprocessable_entity }
      end
    end
  end

View code from new.html.erb:

从 new.html.erb 查看代码：

<% form_for [current_user, @link], :url => account_links_path do |f| %>
<%= render :partial => "form", :locals => { :f => f } %>
<% end %>

And the corresponding partial:

以及相应的部分：

  <%= f.error_messages %>

  <p>
    <%= f.label :uri %><br />
    <%= f.text_field :uri %>
  </p>
  <p>
    <%= f.label :title %><br />
    <%= f.text_field :title %>
  </p>

  <h2>Tags</h2>
  <% f.fields_for :tags_attributes do |tag_form| %>
  <p>
    <%= tag_form.label :name, 'Tag:' %>
    <%= tag_form.text_field :name %>
  </p>
  <% unless tag_form.object.nil? || tag_form.object.new_record? %>
  <p>
    <%= tag_form.label :_delete, 'Remove:' %>
    <%= tag_form.check_box :_delete %>
  </p>
  <% end %>
  <% end %>

  <p>
    <%= f.submit 'Update' %>
  </p>

The following line of code, in the create action in the Link controller throws an error:

下面这行代码，在 Link 控制器的 create 动作中抛出了一个错误：

@link = @current_user.links.build(params[:link])

The error: Tag(#-621698598) expected, got Array(#-609734898)

错误： Tag(#-621698598) expected, got Array(#-609734898)

Are there additional steps needed in the has_many => :through case? These seem to be the only indicated changes for the basic has_many case.

在 has_many => :through 案例中是否需要额外的步骤？这些似乎是基本 has_many 情况的唯一指示更改。

回答by Jyothu

Take a look at the line of your code

看看你的代码行

<% f.fields_for :tags_attributes do |tag_form| %>

You need to use just :tagsinstead of :tags_attributes. This will solve your issue

您需要使用 just:tags而不是:tags_attributes. 这将解决您的问题

Make sure that You have build links and tags in your controller like

确保您在控制器中构建了链接和标签，例如

def new
  @link = @current_user.links.build
  @link.tags.build
end

回答by Tiago

I found this here on stackoverflow:

我在stackoverflow上找到了这个：

Rails nested form with has_many :through, how to edit attributes of join model?

带有 has_many 的 Rails 嵌套表单：通过，如何编辑连接模型的属性？

please tell me if it worked.

请告诉我它是否有效。

回答by jaredonline

In order for this to work, you need to pass in the right params hash:

为了使其工作，您需要传入正确的 params 哈希：

params = {
  :link => {
    :tags_attributes => [
      {:tag_one_attr => ...}, {:tag_two_attr => ...}
    ],
    :link_attr => ...
  }
}

And your controller will look like:

你的控制器看起来像：

def create
  @link = Link.create(params[:link]) # this will automatically build the rest for your
end

回答by obiwanchinobi

Try this:

尝试这个：

<% f.fields_for :tags_attributes do |tag_form| %>

回答by Steve

In your controller in the new action (that loads the form partial), are you building a @tag through your link?

在您的控制器中的新操作（加载表单部分）中，您是否通过链接构建了 @tag？

So you should see something along the lines of:

所以你应该看到一些类似的东西：

@link = Link.new
@tag = @link.tags.build

It might be best to post the contents of the new and create action of your links_controller.

最好发布链接控制器的新内容和创建操作。

回答by soheildb

try

尝试

<% f.fields_for :tags do |tag_form| %> 

(ie lose the _attributes in :tag_attributes) That's how I've usually done nested forms

（即丢失 :tag_attributes 中的 _attributes）这就是我通常完成嵌套表单的方式

回答by Aaron Rentheitroad

You need to build a tag in your controller or in the view

您需要在控制器或视图中构建标签

def new
  @link = @current_user.links.build
  @link.tags.build
end

#in your view you can just use the association name
<% f.fields_for :tags do |tag_form| %>