ruby-on-rails - Rails - 在表单中显示外键引用

Question

我正在用两个模型做一个简单的练习。运动和团队，定义为

rails g scaffold sport name:integer
rails g scaffold team name:integer fans:integer sport:references

(Note: The reason I'm using scaffold is rapidly prototyping so I can learn/experiment with the parts I'm not familiar with yet)

Problem is that my "sport" (i.e. the foreign key reference) is showing like the following

So it's got that weird #<blahl blah> notation to it...

<%= form_for(@team) do |f| %>
  <% if @team.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@team.errors.count, "error") %> prohibited this team from being saved:</h2>

      <ul>
      <% @team.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

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

我试过将一行更改为 @team.sport.name但它会导致错误 undefined method 'Ice Hockey' for #<Team:0x3e7e040> ...关于如何从此处正确显示名称的任何想法？

Answer 1

您正在使用 text_field 来引用现有对象，将 Sports 作为选项的 select 在这里更合适。

这是必须更改的地方:

<div class="field">
  <%= f.label :sport %><br />
  <%= f.text_field :sport %>
</div>

收件人:

<div class="field">
  <%= f.label :sport %><br />
  <%= f.select :sport_id, options_for_select(Sport.all.map{|s|[s.name, s.id]}) %>
</div>

f.select 将在 HTML 中生成一个选择框，选项将包含您数据库中的所有运动。

一些关于它的文档:

• http://apidock.com/rails/ActionView/Helpers/FormOptionsHelper/select
• http://guides.rubyonrails.org/form_helpers.html#select-boxes-for-dealing-with-models

更简洁的方法 是在您的 Controller 中设置一个变量 @sports 然后在您的 View 中调用它:

# in controller
def edit
  @sports = Sport.scoped
  #...

# in edit view
<div class="field">
  <%= f.label :sport %><br />
  <%= f.select :sport_id, options_for_select(@sports.map{ |s| [s.name, s.id] }) %>
</div>

---

附加信息:如果您想为选择“预选”一个选项，您必须将它作为 options_for_select 助手的第二个参数传递:

options_for_select(@sports.map{ |s| [s.name, s.id] }, params[:sport_id])
# this will select by default the option that matches the value of params[:sport_id]