<!-- 表单示例 -->
<%= form_with(model: @model, id: "my_form", local: false) do |f| %>
  <%= f.select :attribute, options_for_select([["Option 1", "1"], ["Option 2", "2"]]), {}, { id: "my_select" } %>
<% end %>

// 使用jQuery UJS处理选择框更改事件
$(document).on('change', '#my_select', function() {
  // 触发表单提交
  $('#my_form').trigger('submit.rails');
});

<!-- 视图文件 -->
<%= form_with(model: @model, id: "dynamic_form", url: update_path(@model), method: :patch, local: false) do |f| %>
  <div class="field">
    <%= f.label :category_id %>
    <%= f.select :category_id, options_for_select(@categories, @model.category_id), 
                 { include_blank: true }, 
                 { class: "form-control", id: "category_select" } %>
  </div>
  
  <!-- 其他字段 -->
  <div class="field">
    <%= f.label :name %>
    <%= f.text_field :name %>
  </div>
<% end %>

<div id="result"></div>

// 在application.js或单独的JS文件中
$(document).on('change', '#category_select', function() {
  // 显示加载状态
  $('#result').html('<div class="loading">处理中...</div>');
  
  // 提交表单
  $('#dynamic_form').trigger('submit.rails');
});

// 处理AJAX响应
$(document).on('ajax:success', '#dynamic_form', function(event) {
  var data = event.detail[0];
  $('#result').html('<div class="success">更新成功: ' + data.message + '</div>');
});

$(document).on('ajax:error', '#dynamic_form', function(event) {
  var xhr = event.detail[2];
  $('#result').html('<div class="error">错误: ' + xhr.status + ' ' + xhr.statusText + '</div>');
});

# 控制器中处理AJAX请求
def update
  @model = Model.find(params[:id])
  
  respond_to do |format|
    if @model.update(model_params)
      format.html { redirect_to @model }
      format.json { render json: { message: "更新成功", data: @model } }
    else
      format.html { render :edit }
      format.json { render json: @model.errors, status: :unprocessable_entity }
    end
  end
end

private

def model_params
  params.require(:model).permit(:category_id, :name)
end