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需要通过关系在has_many的联接模型上创建和更新属性

join has-many-through nested-attributes ruby-on-rails-3.2 ruby-on-rails-3

Betjamin Richards · 技术社区 · 11 年前

我有以下型号:

class Individual < ActiveRecord::Base
  has_many visits
  has_many cities, :through => visits
  accepts_nested_attributes_for :visits, reject_if: proc { |a| a[:city_id].blank? }, allow_destroy: true
end

class Visit < ActiveRecord::Base
  belongs_to individual
  belongs_to city
end

class City < ActiveRecord::Base
  has_many visits
  has_many individuals, :through => visits
end

我正试图为每个人开发一个表格,列出我数据库中的所有城市,并允许他们勾选他们访问过的城市,然后添加有关该城市的一些基本属性。我目前拥有的是:

             <%= form_for(individual) do |f| %>
                  <% for city in cities.each do %>
                    <tr>
                      <td>
                          <%= check_box_tag "individual[visits_attributes][][city_id]", city_id.id, individual.cities.include?(city) %>
                      </td>
                      <td>
                        <label>How good was your visit here?</label>
                        <%= select_tag "individual[visits_attributes][][sentiment]", options_for_select([ ...... ])) %>
                      </td>
                      <td>
                        <label>What was the weather like?</label>
                        <%= select_tag "individual[visits_attributes][][weather]", options_for_select([ ...... ])) %>
                      </td>
                      <td>
                        <label>Where did you stay?</label>
                        <%= select_tag "individual[visits_attributes][][accomodation]", options_for_select([ ...... ])) %>
                      </td>
                    </tr>
                  <% end %>
                  <%= f.submit "Update", :class => "btn" %>
              <% end %>

这有点奏效,但感觉不对,就像脱轨一样。此外,它会创建重复的记录,我还没能让它删除记录。

有人能提出更好的方法吗?或者帮助我重构我已经拥有的东西?

2 回复 | 直到 11 年前

Carlos Drew 11 年前

我没有时间写完整的答案,但要点是你想使用 fields_for 以针对对象输出关联字段。这在Rails中也被称为“嵌套模型表单”。

查看这些资源以获得一些帮助:
Nested Model Form Railscast
Rails API fields_for

Betjamin Richards 11 年前

这就是我最终解决问题的方法。

结合@carlos的输入,我使用Ryan Bates的助手动态添加新的nested_attributes字段,但将其更改为在我的城市列表中工作

<%= form_for(individual) do |f| %>
  <% for city in cities.each do %>
    <% if individual.visits.include?(city) %>
      <% visit = f.object.visits.find_by_city_id(city.id) %>
      <%= f.fields_for(:visits, visit, child_index: visit.id ) do |existing_visit| %>
        <tr>
          <td>
              <%= check_box_tag "individual[visits_attributes][#{visit.id}][city_id]", city.id, individual.visits.include?(city) %>
              <%= existing_visit.hidden_field :_destroy %>
          </td>
          <td>
            <label>How good was your visit here?</label>
            <%= existing_visit.select :sentiment, options_for_select([ ...... ])) %>
          </td>
          <td>
            <label>What was the weather like?</label>
            <%= existing_visit.select :weather, options_for_select([ ...... ])) %>
          </td>
          <td>
            <label>Where did you stay?</label>
            <%= existing_visit.select :accomodation, options_for_select([ ...... ])) %>
          </td>
        </tr>
      <% end %>
    <% else %>
      <% visit = f.object.visits.build %>
      <% random_index = city.id.to_s+"_"+Time.now.to_i.to_s %>
      <%= f.fields_for(:visits, visit, child_index: random_index) do |new_visit| %>
        <tr>
          <td>
              <%= check_box_tag "individual[visits_attributes][#{random_index}][city_id]", city.id, nil %>
          </td>
          <td>
            <label>How good was your visit here?</label>
            <%= new_visit.select :sentiment, options_for_select([ ...... ])) %>
          </td>
          <td>
            <label>What was the weather like?</label>
            <%= new_visit.select :weather, options_for_select([ ...... ])) %>
          </td>
          <td>
            <label>Where did you stay?</label>
            <%= new_visit.select :accomodation, options_for_select([ ...... ])) %>
          </td>
        </tr>
      <% end %>
    <% end %>
    <%= f.submit "Update", :class => "btn" %>
  <% end %>
<% end %>

关键是使用if语句检查记录是新记录还是现有记录,然后在fields_for helper上正确设置child_index:。

我还必须使用check_box_tag而不是.check_box帮助程序,这样它就不会产生隐藏的复选框字段。

当用户取消选中访问所在城市旁边的框时,我使用Javascript触发隐藏字段来删除记录。

如果您需要更多详细信息,请与我们联系。