Question

I m building an app where a User has tasks and a task has a location. The tasks and locations are in a nested_form using formtastic_cocoon, which is the formtastic gem with a jQuery extension.

location.address字段是一个自动完成的文本字段，用于搜索数据库中已存在的地址。因此，当用户选择地址时，表单中会填充一个隐藏的location_id。

我想做的是，当用户编辑任务时，我希望它显示当前选择的地址，但我看不到任何地方可以检索到该值。我可以得到location_id，就像在任务模型中一样，但我似乎无法得到相关的location.address。

模型是

class Task < ActiveRecord::Base
     attr_accessible :user_id, :date, :description, :location_id

     belongs_to :user
     has_one :location
end

class Location < ActiveRecord::Base
     attr_accessible :address, :city, :state, :zip

     has_many :tasks
end

那么以我的形式，我有

  <div class="nested-fields"> 
     <%= link_to_remove_association "remove task", f %>
      <div class="searchAddress">
         < input type="text" value="HERE IS WHERE I WANT TO SHOW THE ADDRESS" >
     </div>
   <%= f.hidden_field :location_id %>
   <%= f.inputs :date, description %>
</div>

-----------经过编辑以包含所有formtastic代码---------------

form.html.erb
<%= semantic_form_for @user, :html=>{:multipart=true} do |form| %>

    <%= form.inputs :username, :photo %>


      <%= form.semantic_fields_for :tasks do |builder | %>

   <%= render  task_fields , :f => builder %>
  <% end %>
<% end %>

------- end edit -------------- I have tried outputing different manner of f , but don t see any reference to the associated locations, yet if I debug User.Task[0].Location outside of the form, I get the correct location details. How do I get that inside the form??

---------更新------------

离这件事越来越近了。原来我可以输出

<%= debug f.object %>

我得到了返回的任务对象。不幸的是，它不包括location对象，只包括location_id字段的值。

Answer 1

你试过@task.location.address吗？

Answer 2

你的方法是正确的。但也有一些遗漏的概念宣告了关联。我想更改如下：

# app/models/task.rb

class Task < ActiveRecord::Base
  attr_accessible :user_id, :location_id, :date, :description

  belongs_to :user
  belongs_to :location
end

由于我们将位置外键存储在任务表中，因此最好在此处声明belongs_to关联。

# app/models/location.rb

class Location < ActiveRecord::Base
  attr_accessible :address, :city, :state, :zip

  has_many :tasks

  # this method will return full address of a location
  def full_address
    [address, city, state, zip].reject(&:blank?).join(", ")
  end
end

然后，您需要添加所选位置的完整地址。

# app/views/users/_task_fields.html.erb

<div class="nested-fields"> 
  <%= link_to_remove_association "remove task", f %>
  
  <div class="searchAddress">
    <input type="text" value="<%= f.object.location&.full_address %>">
  </div>
  
  <%= f.hidden_field :location_id %>
  <%= f.inputs :date, description %>
</div>

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