Container.DataItem的含义

本文详细介绍了ASP.NET中各种数据绑定的方法,包括绑定到简单属性、集合、表达式、方法返回值等多种情况,并对比了不同绑定方式的性能差异。

今天有同事问我这样一个问题:

后台:this.GridView.DataSource=new String[]{"AA","BB","CC"};this.GridView.DataBind();

前台:不知道怎么绑定才能显示初数组的值?

这个问题其实很简单,前台只需要<%#Container.DataItem%>即可,可能最主要问题是大家对这里Container.DataItem不是很理解,一下我做一简单解释:

绑定到简单属性:<%#UserName%>
绑定到集合:<asp:ListBox id="ListBox1" datasource='<%# myArray%>' runat="server">
绑定到表达式:<%#(class1.property1.ToString() + "," + class1.property2.ToString())%>
绑定到方法返回值:<%# GetSafestring(str) %>
绑定到Hashtable:<%# ((DictionaryEntry)Container.DataItem).Key%>
绑定到ArrayList:<%#Container.DataItem %>

若数组里里放的是对象则可能要进行必要的转换后再绑定如:
<%#((对象类型)Container.DataItem).属性%>

绑定到DataView,DataTable,DataSet:
<%#((DataRowView)Container.DataItem)["字段名"]%>或
<%#((DataRowView)Container.DataItem).Rows[0]["字段名"]%>
要格式化则:
<%#string.Format("格式",((DataRowView)Container.DataItem)["字段名"])%>
<%#DataBinder.Eval(Container.DataItem,"字段名","格式")%>

绑定到DataReader:
<%#((IDataReader)Container.DataItem).字段名%>

当然为了方便一般使用最多的就是DataBinder类的Eval方法了.不过这样对于同时要绑定大量的数据效率要低一些

在绑定数据时经常会用到这个句程序:<%# DataBinder.Eval(Container.DataItem,"xxxx")%>或者<%# DataBinder.Eval(Container,"DataItem.xxxx")%>
今天又学到一种,而且微软也说这种方法的效率要比以上两种高。

<%# ((DataRowView)Container.DataItem)["xxxx"]%>

很有用的,这样可以在前台页面做好多事情了。

还要记住要这样用必须要在前台页面导入名称空间System.Data,否则会生成错误信息。

<%@ Import namespace="System.Data" %>

这种用法其实和<%# ((DictionaryEntry)Container.DataItem).Key%>是一个道理。

绑定到DataSet、DataTable时:

<%#((System.Data.DataRowView)Container.DataItem)["字段名"]%>
<%#((System.Data.DataRowView)Container.DataItem)[索引]%>


绑定到DataReader时:
<%#((System.Data.Common.DbDataRecord)Container.DataItem)[索引]%>
<%#((System.Data.Common.DbDataRecord)Container.DataItem)["字段名"]%>

关键是Container这个东西,它比较神秘。它的名称空间是System.ComponentModel。对于它我还需要进一步理解。

初学.NET,现在在看DataGrid控件,在ItemTemplate显示数据时,
DataBinder.Eval(Container.DataItem,"Name")和Container.DataItem("Name")有什么区别?


DataBinder是System.Web里面的一个静态类,它提供了Eval方法用于简化数据绑定表达式的编写,但是它使用的方式是通过 Reflection等开销比较大的方法来达到易用性,因此其性能并不是最好的。而Container则根本不是任何一个静态的对象或方法,它是 ASP.NET页面编译器在数据绑定事件处理程序内部声明的局部变量,其类型是可以进行数据绑定的控件的数据容器类型(如在Repeater内部的数据绑定容器叫RepeaterItem),在这些容器类中基本都有DataItem属性,因此你可以写Container.DataItem,这个属性返回的是你正在被绑定的数据源中的那个数据项。如果你的数据源是DataTable,则这个数据项的类型实际是DataRowView。

最后感谢:http://hi.baidu.com/superxxpp/blog/item/a8c69e4a59e8732a08f7ef5f.html

import { h, createApp, ref, nextTick } from 'vue' import A4Page from '@/components/A4Page/index.vue' import moment from "moment"; export const createTempComponentAndGenerateImage = function (data) { console.log(data) return new Promise((resolve, reject) => { // 创建隐藏的 DOM 容器 const container = document.createElement('div') container.style.position = 'absolute' container.style.right = '0px' container.style.top = '0' container.style.backgroundColor = 'red' container.style.zIndex = 99999 document.body.appendChild(container) // 创建 ref const a4PageRef = ref(null) // 定义自定义事件处理函数 const getBlodData = (payload) => { console.log('接收到 A4Page 组件的自定义事件:', payload) // 可以在这里执行后续逻辑 } const dataFormat = (formatData) => { let meetingTime = '', compereList = '', userList = '', attendList = '', absenteeList = '', recorderList = ''; // 处理会议时间 if (formatData.meetingTime) { meetingTime = moment(formatData.meetingTime).format("YYYY-MM-DD HH:mm") } // 处理主持人字段 if (formatData.compereList && formatData.compereList.length > 0) { compereList = formatData.compereList.map(item => item.userName).join(',') } // 处理及记录人字段 if (formatData.recorderList && formatData.recorderList.length > 0) { recorderList = formatData.recorderList.map(item => item.userName).join(',') } // 处理参会人员字段 if (formatData.userList && formatData.userList.length > 0) { userList = formatData.userList.map(item => item.userName).join(',') } // 处理实到人员字段 if (formatData.attendList && formatData.attendList.length > 0) { attendList = formatData.attendList.map(item => item.userName).join(',') } // 处理缺席人员字段 if (formatData.absenteeList && formatData.absenteeList.length > 0) { absenteeList = formatData.absenteeList.map(item => { if (item.reason) { return `${item.userName}(${item.reason})` } else { return `${item.userName}` } }).join(',') } return { meetingTypeField: formatData.meetingTypeField, // 会议类型 meetingTheme: formatData.meetingTheme, // 主题 meetingTime, // 时间 meetingAddr: formatData.meetingAddr, // 地点 compereList, // 主持人 recorderList, // 记录人 userList, // 参会人员 attendList, // 实到人员 absenteeList, // 缺席人员 observer: formatData.observer, // 列席人员 meetingContent: formatData.meetingContent // 会议内容 } } // 创建临时组件(直接使用 A4Page) const TempComponent = { setup () { return () => h(A4Page, { // 1. 绑定 ref ref: a4PageRef, // 2. 传入 props pageData: dataFormat(data), // 3. 绑定自定义事件(注意命名方式为 onEventName) getBlodData: getBlodData }) } } // 创建 Vue 应用并挂载组件 const app = createApp(TempComponent) const instance = app.mount(container) // // 模拟组件挂载后执行的逻辑 // setTimeout(() => { // // 此时可以访问组件实例 // if (a4PageRef.value) { // console.log('A4Page 实例:', a4PageRef.value) // // 假设 A4Page 中有方法 generateContent,可以调用它 // if (typeof a4PageRef.value.initA4Page === 'function') { // // a4PageRef.value.initA4Page() // nextTick(() => { // console.log(a4PageRef.value.initA4Page) // }) // } // } // // 此处你可以调用 html2canvas 来截图 // // import html2canvas from 'html2canvas' // // html2canvas(container).then(canvas => { // // resolve(canvas.toDataURL()) // // }) // // 模拟成功返回 // resolve('组件已渲染完成') // }, 100) }) } 如何判断临时的创建的组件是全部还在完成的,
08-15
解读SELECT sum(CASE WHEN jthgl.data_value1 = '不合格品' THEN car_num ELSE 0 END )AS bhg, sum(CASE WHEN jthgl.data_value1 != '不合格品' THEN car_num ELSE 0 END )AS hgp, sum(CASE WHEN jthgl.data_value1 IS NOT NULL THEN car_num ELSE 0 END )AS zongshu, (sum(CASE WHEN jthgl.data_value1 != '不合格品' THEN car_num ELSE 0 END )/ sum(CASE WHEN jthgl.data_value1 IS NOT NULL THEN car_num ELSE 0 END ))* 100 AS HEGELV FROM ( SELECT * FROM ( SELECT a.*, b.data_value1, trunc((rn - 1) / 5) rshang, MOD((rn - 1), 5) rmod, CASE WHEN a.CONTAINER_NR IS NOT NULL THEN listagg(a.CONTAINER_NR, ',') WITHIN GROUP( ORDER BY a.CONTAINER_NR) OVER(PARTITION BY a.COMM_NR) END carorCon FROM ( SELECT t.COMM_NR, --t.CAR_NUM, t.mat_nr, t.mat_desc, t.mat_nr || '-' || t.mat_desc matCode, trunc(t.created_dt) post_dt, t.vendor_desc, t.level_result, a.CREATED_BY_NAME, a.ORIGIN_DESC, CASE WHEN b.CONTAINER_NR IS NULL THEN b.CAR_NO ELSE b.CONTAINER_NR END CONTAINER_NR, --b.CAR_NO, b.ms_bill_nr, ROW_NUMBER() OVER(PARTITION BY a.comm_nr ORDER BY trunc(t.created_dt) DESC) rn FROM IR_QL_INSP_COMM T, IR_BU_STOCK_BUSI a, IR_BU_STOCK_ITEM b WHERE t.comm_nr = a.comm_nr AND a.STOCK_BUSI_NR = b.STOCK_BUSI_NR AND T.MAT_NR IN ('R0000056', 'R0000229') AND t.comm_nr IN ( SELECT DISTINCT comm_nr FROM IR_QL_INSP_ITEM b WHERE to_char(b.end_dt,'yyyy-mm-dd') = ?)) a LEFT JOIN ( SELECT T.KEY_VALUE1, T.DATA_VALUE1 FROM IR_MD_REFERENCE_DATA_ITEM T WHERE T.REFERENCE_DATA_ID = 'LEVEL_RESULT') b ON a.level_result = b.KEY_VALUE1) x LEFT JOIN ( SELECT t.comm_nr comm_nr_c, count(b.car_no) car_num FROM IR_QL_INSP_COMM T, IR_BU_STOCK_BUSI a, IR_BU_STOCK_ITEM b WHERE t.comm_nr = a.comm_nr AND a.STOCK_BUSI_NR = b.STOCK_BUSI_NR AND T.MAT_NR IN ('R0000056', 'R0000229') AND t.comm_nr IN ( SELECT DISTINCT comm_nr FROM IR_QL_INSP_ITEM b WHERE to_char(b.end_dt,'yyyy-mm-dd') = ?) GROUP BY t.comm_nr) y ON x.comm_nr = y.comm_nr_c)jthgl
08-05
<template> <div class="conversation-container"> <div class="conversation-list"> <div class="conversation-list-item"> <div class="conversation-list-title">待接入 {{ pendingConversations.length }}</div> <div class="conversation-list-body"> <router-link tag="div" :to="chat(conversation)" replace v-for="(conversation, key) in pendingConversations" :key="key"> <div class="conversation-item"> <div class="conversation-item-head"> <img :src="conversation.data.avatar" class="conversation-item-avatar" /> </div> <div class="item-info"> <div class="item-info-name">{{ conversation.data.name }}</div> <div v-if="conversation.lastMessage.type === 'text'" class="item-info-message"> {{ conversation.lastMessage.payload.text }} </div> <div v-else-if="conversation.lastMessage.type === 'image'" class="item-info-message">[图片消息]</div> <div v-else-if="conversation.lastMessage.type === 'video'" class="item-info-message">[视频消息]</div> <div v-else-if="conversation.lastMessage.type === 'audio'" class="item-info-message">[语音消息]</div> <div v-else-if="conversation.lastMessage.type === 'order'" class="item-info-message">[自定义消息:订单] </div> <div v-else-if="conversation.lastMessage.type === 'CS_END'" class="item-info-message">会话已结束</div> <div v-else-if="conversation.lastMessage.type === 'CS_ACCEPT'" class="item-info-message">接入成功</div> <div v-else-if="conversation.lastMessage.type === 'CS_TRANSFER'" class="item-info-message"> {{ conversation.lastMessage.senderId === currentAgent.id ? `已转接给` + conversation.lastMessage.payload.transferTo.data.name : '已接入来自' + conversation.lastMessage.senderData.name + '的转接' }} </div> <div v-else class="item-info-message">[未识别内容]</div> </div> </div> </router-link> </div> </div> <div class="conversation-list-item"> <div class="conversation-list-title">已接入 {{ conversations.length }}</div> <div v-if="conversations.length" class="conversation-list-body"> <router-link tag="div" :to="chat(conversation)" replace v-for="(conversation, key) in conversations" :key="key"> <div class="conversation-item" @contextmenu.prevent.stop="e => showRightClickMenu(e, conversation)"> <div class="conversation-item-head"> <img :src="conversation.data.avatar" class="conversation-item-avatar" /> <span v-if="conversation.unread" class="conversation-item-unread">{{ conversation.unread }}</span> </div> <div class="conversation-item-info"> <div class="item-info-top"> <div class="item-info-name">{{ conversation.data.name }}</div> <div class="item-info-time">{{ formatDate(conversation.lastMessage.timestamp) }}</div> </div> <div class="item-info-bottom"> <div v-if="conversation.lastMessage.status === 'sending'" class="item-info-sending"></div> <div v-if="conversation.lastMessage.status === 'fail'" class="item-info-failed"></div> <div v-if="conversation.lastMessage.type === 'text'" class="item-info-message"> {{ conversation.lastMessage.senderId === currentAgent.id ? '你' : conversation.lastMessage.senderData.name }}: {{ conversation.lastMessage.payload.text }} </div> <div v-else-if="conversation.lastMessage.type === 'image'" class="item-info-message">[图片消息]</div> <div v-else-if="conversation.lastMessage.type === 'video'" class="item-info-message">[视频消息]</div> <div v-else-if="conversation.lastMessage.type === 'audio'" class="item-info-message">[语音消息]</div> <div v-else-if="conversation.lastMessage.type === 'order'" class="item-info-message">[自定义消息:订单] </div> <div v-else-if="conversation.lastMessage.type === 'CS_END'" class="item-info-message">会话已结束</div> <div v-else-if="conversation.lastMessage.type === 'CS_ACCEPT'" class="item-info-message">接入成功</div> <div v-else-if="conversation.lastMessage.type === 'CS_TRANSFER'" class="item-info-message"> {{ conversation.lastMessage.senderId === currentAgent.id ? `已转接给` + conversation.lastMessage.payload.transferTo.data.name : '已接入来自' + conversation.lastMessage.senderData.name + '的转接' }} </div> <div v-else class="item-info-message">[未识别内容]</div> </div> </div> </div> </router-link> </div> </div> <div v-if="rightClickMenu.visible" :style="{ 'left': rightClickMenu.x + 'px', 'top': rightClickMenu.y + 'px' }" class="action-box"> <div class="action-item" @click="topConversation">{{ rightClickMenu.conversation.top ? '取消置顶' : '置顶' }}</div> <div class="action-item" @click="deleteConversation">删除聊天</div> </div> </div> <div class="conversation-main"> <router-view :key="$route.params.id"></router-view> </div> </div> </template> <script setup> import { ref, onMounted, onBeforeUnmount } from 'vue'; import { useRouter, useRoute } from 'vue-router'; import { formatDate } from '../utils/utils.js'; import GoEasy from 'goeasy'; // 引入真实的 GoEasy SDK import { useCounterStore } from '../stores/counter.js' const router = useRouter(); const route = useRoute(); // 定义响应式数据 const pendingConversations = ref([]); const conversations = ref([]); const rightClickMenu = ref({ conversation: null, visible: false, x: null, y: null, }); const currentAgent = ref(null); // 初始化 GoEasy const goEasy = GoEasy.getInstance({ host: 'hangzhou.goeasy.io', //应用所在的区域地址: 【hangzhou.goeasy.io |singapore.goeasy.io】 appkey: 'BC-f00d5ee0720d4dab888ca1b5536483ab', // common key, modules: ['im'], }); console.log('GoEasy initialized:', goEasy); console.log('GoEasy IM module:', goEasy.im); // 检查 IM 模块是否存在 // 其他代码保持不变... const loadConversations = () => { goEasy.im.pendingConversations({ onSuccess: (result) => { console.log('待接入会话:', result.content.conversations); renderPendingConversations(result.content); }, onFailed: (error) => { console.log('获取待接入列表失败:', error); }, }); goEasy.im.latestConversations({ onSuccess: (result) => { console.log('已接入会话:', result.content.conversations); renderLatestConversations(result.content); }, onFailed: (error) => { console.log('获取已接入列表失败:', error); }, }); }; const listenConversationUpdate = () => { // 监听会话列表变化 goEasy.im.on(goEasy.IM_EVENT.CONVERSATIONS_UPDATED, renderLatestConversations); goEasy.im.on(goEasy.IM_EVENT.PENDING_CONVERSATIONS_UPDATED, renderPendingConversations); }; const renderPendingConversations = (content) => { pendingConversations.value = content.conversations; }; const renderLatestConversations = (content) => { conversations.value = content.conversations; }; const chat = (conversation) => { return { path: `/conversations/chat/${conversation.id}`, query: { name: conversation.data.name, avatar: conversation.data.avatar, }, }; }; const showRightClickMenu = (e, conversation) => { rightClickMenu.value.conversation = conversation; rightClickMenu.value.visible = true; rightClickMenu.value.x = e.pageX; rightClickMenu.value.y = e.pageY; }; const hideRightClickMenu = () => { rightClickMenu.value.visible = false; }; const topConversation = () => { const conversation = rightClickMenu.value.conversation; const description = conversation.top ? '取消置顶' : '置顶'; goEasy.im.topConversation({ top: !conversation.top, conversation: conversation, onSuccess: () => { console.log(description, '成功'); }, onFailed: (error) => { console.log(description, '失败:', error); }, }); }; const deleteConversation = () => { if (!rightClickMenu.value.conversation.ended) { alert('删除失败:会话尚未结束'); return; } if (confirm('确认要删除这条会话吗?')) { goEasy.im.removeConversation({ conversation: rightClickMenu.value.conversation, onSuccess: () => { console.log('删除会话成功'); }, onFailed: (error) => { console.log(error); }, }); } }; onMounted(() => { // 隐藏 Conversation 右键菜单 document.addEventListener('click', hideRightClickMenu); // 获取当前客服信息 currentAgent.value = useCounterStore().currentAgent; console.log(currentAgent.value); // 监听 GoEasy 连接状态 goEasy.connect({ onSuccess: () => { console.log('GoEasy connected successfully'); // 确保用户信息存在 if (!currentAgent.value || !currentAgent.value.id || !currentAgent.value.name || !currentAgent.value.avatar) { console.error('Agent information is incomplete'); return; } // 登录IM goEasy.im.login({ id: currentAgent.value.id, // 必须 data: { // 必须 name: currentAgent.value.name, avatar: currentAgent.value.avatar, // 添加其他必要字段 }, onSuccess: () => { console.log('IM login success'); listenConversationUpdate(); loadConversations(); }, onFailed: (error) => { console.error('IM login failed:', error); } }); }, onFailed: (error) => { console.error('GoEasy connection failed:', error); } }); }); </script> <style scoped> .conversation-container { width: 100%; height: 100%; display: flex; background: #FFFFFF; } .conversation-list { width: 220px; border-right: 1px solid #eee; display: flex; flex-direction: column; padding: 10px; position: relative; } .conversation-list-title { font-size: 15px; margin: 5px 10px; color: rgba(0, 0, 0, 0.9); } .conversation-list-body { overflow-y: auto; max-height: 350px; scrollbar-width: none; -ms-overflow-style: none; } .conversation-list-body::-webkit-scrollbar { display: none; } .action-box { width: 100px; height: 60px; background: #ffffff; border: 1px solid #cccccc; position: fixed; z-index: 100; border-radius: 5px; } .action-item { padding-left: 15px; line-height: 30px; font-size: 13px; color: #262628; cursor: pointer; } .action-item:hover { background: #dddddd; } .conversation-item { display: flex; padding: 10px; cursor: pointer; } .conversation-item-head { position: relative; margin-right: 5px; } .conversation-item-avatar { width: 40px; height: 40px; border-radius: 4px; } .conversation-item-unread { position: absolute; top: -9px; right: -9px; width: 18px; height: 18px; line-height: 18px; border-radius: 50%; text-align: center; color: #fff; font-size: 12px; background-color: #fa5151; } .conversation-item-info { flex: 1; display: flex; flex-direction: column; justify-content: space-between; } .item-info-top { display: flex; justify-content: space-between; align-items: center; } .item-info-name { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; word-break: break-all; font-size: 15px; width: 80px; line-height: 25px; color: #333333; } .item-info-time { color: #666666; font-size: 12px; } .item-info-bottom { display: flex; align-items: center; } .item-info-message { font-size: 12px; line-height: 20px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; width: 150px; color: #606266; } .item-info-failed { background: url("../assets/images/failed.png") no-repeat center; background-size: 12px; width: 12px; height: 12px; margin-right: 2px; } .item-info-sending { background: url("../assets/images/pending.gif") no-repeat center; background-size: 12px; width: 12px; height: 12px; margin-right: 2px; } .router-link-active { background: #eeeeee; border-radius: 5px; } .conversation-main { flex: 1; background: #FFFFFF; } </style>我在用GoEasy实现即时通讯时报错code: 400, content: 'data: id and data are required for IM module
06-10
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