动态Turbo Stream内容权限控制：Stimulus与AJAX实现指南

# app/controllers/application_controller.rb
class ApplicationController < ActionController::Base
  # ... 其他代码 ...

  def turbo_stream?
    request.format.turbo_stream?
  end
  helper_method :turbo_stream?
end

<!-- app/views/resource/_resource.html.erb -->
<%= turbo_frame_tag resource do %>
  <div id="<%= dom_id resource %>"
       data-controller="resource-permissions" <!-- 添加Stimulus控制器 -->
       data-resource-url="<%= resource_path(resource, format: :json) %>">

    <!-- 您的其他资源内容 -->

    <% if turbo_stream? || policy(resource).edit? %>
      <%= link_to edit_resource_path(resource),
                  class: "btn btn-primary #{'d-none' if turbo_stream?}",
                  data: { resource_action: :edit } do %>
        <i class="las la-edit"></i>
        <span class="d-none d-lg-inline">
          <%= t("buttons.edit") %>
        </span>
      <% end %>
    <% end %>

    <% if turbo_stream? || policy(resource).destroy? %>
      <%= link_to resource,
                  class: "btn btn-danger #{'d-none' if turbo_stream?}",
                  data: {
                    resource_action: :destroy,
                    turbo_confirm: t("confirm.short"),
                    turbo_method: :delete
                  } do %>
        <i class="las la-trash-alt"></i>
        <span class="d-none d-lg-inline">
          <%= t("buttons.remove") %>
        </span>
      <% end %>
    <% end %>

  </div>
<% end %>

# app/views/resources/_resource.json.jbuilder
json.extract! resource, :id, :name # 提取其他必要字段
json.permissions do
  json.edit policy(resource).edit?
  json.destroy policy(resource).destroy?
end

// app/javascript/controllers/turbostream_controller.js
import Rails from "@rails/ujs"
import { Controller } from "@hotwired/stimulus"

export default class extends Controller {
  connect() {
    // 监听 turbo:before-stream-render 事件
    // 这个事件在Turbo Stream渲染之前触发，允许我们修改渲染行为
    addEventListener("turbo:before-stream-render", this.beforeStreamRender.bind(this))
  }

  disconnect() {
    // 清理事件监听器，避免内存泄漏
    removeEventListener("turbo:before-stream-render", this.beforeStreamRender.bind(this))
  }

  beforeStreamRender(event) {
    // 保存Turbo Stream默认的渲染函数
    const defaultAction = event.detail.render

    // 覆盖 event.detail.render，以便在默认渲染完成后执行我们的逻辑
    event.detail.render = (streamElement) => {
      // 首先执行Turbo Stream的默认渲染
      defaultAction(streamElement)
      try {
        // 然后执行我们的自定义处理逻辑
        this.processStream(streamElement)
      } catch(error) {
        console.error("Error processing Turbo Stream:", error)
      }
    }
  }

  processStream(streamElement) {
    // 检查Turbo Stream的操作类型，我们主要关心添加、更新、替换操作
    if (["prepend", "append", "update", "replace"].includes(streamElement.action)) {
        // streamElement.children[0].content 包含了即将被插入或更新的HTML片段
        const template = streamElement.children[0].content
        // 查找带有 data-resource-url 属性的元素
        const templateDiv = template.querySelector('[data-resource-url]')

        if (templateDiv) {
          // 获取资源的ID，通常是 dom_id
          const id = templateDiv.getAttribute('id')
          // 调用函数设置按钮可见性
          this.setActionButtonVisibility(id)
        }
    }
  }

  setActionButtonVisibility(id) {
    // 找到刚刚被渲染到DOM中的资源容器
    const div = document.querySelector(`div#${id}`)
    if (!div) return; // 如果元素不存在，则退出

    // 获取资源URL和操作按钮
    const url = div.getAttribute('data-resource-url')
    const editButton = div.querySelector('[data-resource-action="edit"]')
    const destroyButton = div.querySelector('[data-resource-action="destroy"]')

    // 使用 Rails UJS 发送 AJAX 请求获取权限
    Rails.ajax({
      type: "GET",
      url: url,
      dataType: "json", // 明确指定期望的响应类型为JSON
      success: (data, _status, _xhr) => {
        try {
          if (editButton) {
            // 根据权限数据切换 'd-none' 类
            editButton.classList.toggle('d-none', !data.permissions.edit)
          }
          if (destroyButton) {
            destroyButton.classList.toggle('d-none', !data.permissions.destroy)
          }
        } catch(error) {
          console.error("Error updating button visibility:", error)
        }
      },
      error: (xhr, status, error) => {
        console.error(`Failed to fetch permissions for ${url}:`, error, status, xhr);
      }
    })
  }
}

<!-- app/views/resource/index.html.erb -->
<div data-controller="turbostream">
  <%= turbo_stream_from "resources" %>
  <div id="resources">
    <% @resources.each do |resource| %>
      <%= render resource %>
    <% end %>
  </div>
</div>