无法使用has_one关联获取嵌套表单 [英] Cannot get nested form with a has_one association to work

问题描述

我有以下模型:

class User < ActiveRecord::Base
    has_one :city
    accepts_nested_attributes_for :city
end

class City < ActiveRecord::Base
    belongs_to :user
end

此控制器操作:

   def create
    @user = User.new(params[:user])

    respond_to do |format|
      if @user.save
        format.html { redirect_to(@user, :notice => 'User was successfully created.') }
        format.xml  { render :xml => @user, :status => :created, :location => @user }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @user.errors, :status => :unprocessable_entity }
      end
    end
  end

和此视图:

<%= form_for :user,:url => users_path,:method => :post do |f| %>
<%= f.fields_for :city do |b| %>
    <%= b.collection_select :id,City.all,:id,:name %>
  <% end %>

  <div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

我正试图允许用户从已添加的城市列表中选择一个城市.我正在尝试给他一个选择.选择部分可以正常工作，但是为其生成的html代码如下所示:

I am trying to allow the user to select a city from the list of already added cities. I am trying to present him a select. The select part it works, but the generated html code for it, looks like this:

<select name="user[city][id]" id="user_city_id">
   <option value="1">One</option>
   <option value="2">Two</option>
</select>

请注意，它的名称在任何地方都没有attribute.因此，当我尝试保存它时，出现此错误:

Notice that it's name doesn't have attribute anywhere. So, when I try to save it, I get this error:

City(#37815120) expected, got ActiveSupport::HashWithIndifferentAccess(#32969916)

我该如何解决?

有一些进展，我试图将fields_for更改为此:

there is some progress, I tried to change the fields_for to this:

<%= f.fields_for :city_attributes do |b| %>
    <%= b.collection_select :id,City.all,:id,:name %>
<% end %>

现在，html似乎可以正确生成.但是我现在收到此错误:

and now, the html seems to generate correctly. But I get this error now:

Couldn't find City with ID=1 for User with ID=

我不知道下一步该怎么做.

I have no idea what to do next.

覆盖city_attributes=方法似乎有效:

def city_attributes=(attribs)
    self.city = City.find(attribs[:id])
end

我不知道这是不是要走的路，但这似乎很好.

I don't know if it's the way to go, but it seems good.

推荐答案

看看这个与您的问题相似的问题: 第3条:"accepts_nested_attributes_for"如何实现?工作吗?

Have a look at this question that seems similar to yours : Rails 3: How does "accepts_nested_attributes_for" work?

实际上，由于城市已经存在，我认为这里不需要嵌套表格.

Actually, since the Cities already exsit, I think there is no need for nested forms here.

尝试更换

<%= f.fields_for :city_attributes do |b| %>
    <%= b.collection_select :id,City.all,:id,:name %>
<% end %>

使用

<%= f.collection_select :city, City.all,:id,:name %>

评论后更新

您可以更改与您的关系(并相应地更新数据库方案)

Could you change your relationship with (and update database scheme accordingly)

class User < ActiveRecord::Base
    belongs_to :city
end

class City < ActiveRecord::Base
    has_many :users
end

然后尝试使用:

<%= f.collection_select :city_id, City.all,:id,:name %>

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