RoR - 调用 fields_for 可变次数的辅助方法

Question

在我的 Rails 应用程序中，我有一个多次使用fields_for 的表单，有时会嵌套调用fields_for。

不幸的是，图形设计师坚持输入字段的排序方式不能根据它们所属的模型进行分组。因此，我想制作一个可以轻松构建fields_for 块的助手，但我看不到如何让助手方法嵌套可变数量的块。

为了说明，我设想代码如下所示：

<%= form_for @object do |f| %>
  <!-- The helper method should have a similar effect to the following... -->
  <%= f.fields_for :assoc_a do |assoc_a_builder| %>
    <%= assoc_a_builder.fields_for :assoc_b do |assoc_b_builder| %>
      <%= assoc_b_builder.text_field :field_name %>
    <% end %>
  <% end %>      
  <!-- ...when given the following data... -->
  <%= my_helper [f, :assoc_a, :assoc_b], :text_field, :field_name %>

<% end %>

知道我该如何做到这一点吗？

Answer 1

我实现了以下辅助方法（可能不是最好的方法）。

视图中的示例函数调用：

<%= form_for @object do |builder| %>
  <%= nested_form_field 'My label text', [builder, :association_name, :field_name], :collection_select, :my_model_id, MyModel.all, :id, :name %>
<% end %>

函数定义：

  # Outputs a label and input, nesting calls to fields_for if 'form' arg is an Array.
  # e.g. <%= nested_form_field nil, [builder, :approved_details], :collection_select, :my_model_id, MyModel.all, :id, :name %>
  # Make label_text nil for just the input tag, no wrapping elements.
  def nested_form_field label_text, form, helper_method, field, *args_for_helper_method
    if form.is_a? Array
      if form.length > 1
        form.shift.fields_for form.first do |builder|
          form[0] = builder
          nested_form_field label_text, form, helper_method, field, *args_for_helper_method
        end
      else
        nested_form_field label_text, form.first, helper_method, field, *args_for_helper_method
      end
    else
      if label_text.nil?
        form.send helper_method, field, *args_for_helper_method
      else
        %Q(<div class=row>
        <div class=span4>#{label_text}</div>
        #{ form.send helper_method, field, *args_for_helper_method }
        </div>).html_safe
      end
    end
  end

Answer 2

<%= simple_form_for(@primer3) do |f| %>
  <%= f.error_notification %>

  <div class="form-inputs">
    <% @primer3.attributes.each_pair do |name, value| %>
      <%= f.input name if value %>
    <% end %>
  </div>

  <div class="form-actions">
    <%= f.button :submit %>
  </div>
<% end %>