在Turbo Streams中实现基于用户权限的动态UI更新

# app/controllers/application_controller.rb

class ApplicationController < ActionController::Base
  # ... 其他代码 ...

  def turbo_stream?
    formats.any?(: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-resource-url="<%= resource_path(resource, format: :json) %>">

    <!-- 省略其他内容 -->

    <% 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, :description # 假设资源有id, name, description字段
# ... 其他资源属性 ...

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
    addEventListener("turbo:before-stream-render",
                     (e) => { this.beforeStreamRender(e) })
  }

  beforeStreamRender(event) {
    // 保存 Turbo Stream 默认的渲染行为
    const defaultAction = event.detail.render
    // 覆盖 event.detail.render 方法，在默认渲染之后执行我们的自定义逻辑
    event.detail.render = (streamElement) => {
      defaultAction(streamElement) // 执行 Turbo Stream 的默认渲染
      try { this.processStream(streamElement) } // 执行我们的权限处理
      catch(error) { console.error("Error processing Turbo Stream:", error) }
    }
  }

  processStream(streamElement) {
    // 检查 Turbo Stream 的操作类型，只处理 'prepend', 'append', 'update'
    if (["prepend", "append", "update"].includes(streamElement.action)) {
        // 获取 streamElement 中的模板内容
        var template = streamElement.children[0].content
        // 在模板内容中查找带有 data-resource-url 属性的元素
        var templateDiv = template.querySelector('[data-resource-url]')
        if (templateDiv != null) {
          var id = templateDiv.getAttribute('id')
          // 如果找到，则调用 setActionButtonVisibility 来更新按钮可见性
          this.setActionButtonVisibility(id)
        }
    }
  }

  setActionButtonVisibility(id) {
    // 根据 ID 获取已渲染到 DOM 中的资源 div
    var div = document.querySelector(`div#${id}`)
    if (!div) {
      console.warn(`Resource div with ID ${id} not found after stream render.`);
      return;
    }
    // 获取资源的 JSON URL
    var url = div.getAttribute('data-resource-url')
    // 获取编辑和删除按钮
    var editButton = div.querySelector('[data-resource-action="edit"]')
    var destroyButton = div.querySelector('[data-resource-action="destroy"]')

    // 使用 Rails.ajax 发送 GET 请求获取权限
    Rails.ajax({
      type: "GET",
      url: url,
      success: (data, _status, _xhr) => {
        try {
          // 根据返回的权限数据切换按钮的 d-none 类
          if (editButton) {
            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 resource ${id}:`, status, error);
      }
    })
  }
}

<!-- app/views/resource/index.html.erb -->

<div data-controller="turbostream">
  <%= turbo_frame_tag "resources" do %>
    <% @resources.each do |resource| %>
      <%= render resource %>
    <% end %>
  <% end %>
</div>