asp.net:AJAX+LINQ+TreeView 动态填充多级节点

演示示例为一个学生信息查看菜单：先选择部门，再选择班级，最后选择学生姓名，查看学生信息；

效果图：

 

 

采用TreeView的SelectedNodeChanged事件作为一个包含用来显示学生信息的Lable的UpdatePanel的触发器，如下：

<form id="form1" runat="server"> <div> <asp:ScriptManager ID="ScriptManager1" runat="server"> </asp:ScriptManager> <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional"> <ContentTemplate> <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label> </ContentTemplate> <Triggers> <asp:AsyncPostBackTrigger ControlID="TreeView1" EventName="SelectedNodeChanged" /> </Triggers> </asp:UpdatePanel> <asp:TreeView ID="TreeView1" runat="server" onselectednodechanged="TreeView1_SelectedNodeChanged" ontreenodepopulate="TreeView1_TreeNodePopulate" Width="169px" ExpandDepth="0" ShowLines="True"> <Nodes> <asp:TreeNode Text="部门->班级->学生" SelectAction="Expand" PopulateOnDemand="true" Value="请选择"></asp:TreeNode> </Nodes> </asp:TreeView> </div> </form>

 

其中一些涉及数据库的查询，采用LINQ的写法，再此不多作说明，其先决条件：在“服务器资源管理器”中添加连接，选择数据库，右击“解决方案资源管理器”，选择“添加新项”，选择“LINQ to sql类”，将你需要用的表从“服务器资源管理器”拖入跳出的界面中，一定要保存，好了，完整代码如下：

using System; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; using System.Text;//StringBuilder所在命名空间 public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e) { JWInfoDataContext db = new JWInfoDataContext(); //LNNQ写法 var result = (from stuIn in db.学生信息 where stuIn.学号.ToString() == this.TreeView1.SelectedNode.Value.ToString() select stuIn).First(); if (result != null) { StringBuilder strStuInfo = new StringBuilder(); strStuInfo.AppendLine("学号：" + result.学号.ToString()); strStuInfo.AppendLine("<br />姓名：" + result.姓名.ToString()); strStuInfo.AppendLine("<br />性别：" + result.性别.ToString()); strStuInfo.AppendLine("<br />班级编号：" + result.班级编号.ToString()); Label1.Text = strStuInfo.ToString(); } else { Label1.Text = "没有数据！"; } } protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e) { //获取根节点深度，****注意***设置TreeView的ExpandDepth="0"，即默认根节点深度为0 switch (e.Node.Depth) { case 0://填充一级节点 PopulateDept(e.Node); break; case 1://填充二级节点 PopulateClassID(e.Node); break; case 2://三级 PopulateStu(e.Node); break; default: break; } } /// <summary> /// 填充一级节点的代码 /// </summary> /// <param name="node"></param> private void PopulateDept(TreeNode node) { DataTable dt = RunQuery("PopulateDept", null); if (dt.Rows.Count > 0) { foreach (DataRow row in dt.Rows) { //创建一级节点 TreeNode newNode = new TreeNode(); newNode.Text = row["部门名称"].ToString(); newNode.Value = row["部门编号"].ToString(); //指示为动态填充节点 newNode.PopulateOnDemand = true; //设置选择节点时激发TreeNodeExpanded 事件 newNode.SelectAction = TreeNodeSelectAction.Expand; //将子节点加入父节点中 node.ChildNodes.Add(newNode); } } } /// <summary> /// 填充二级节点 /// </summary> /// <param name="node"></param> private void PopulateClassID(TreeNode node) { DataTable dt = RunQuery("PopulateClassID", node.Value); if (dt.Rows.Count > 0) { foreach (DataRow row in dt.Rows) { TreeNode newNode = new TreeNode(); newNode.Text = row["班级名称"].ToString(); newNode.Value = row["班级编号"].ToString(); newNode.PopulateOnDemand = true; newNode.SelectAction = TreeNodeSelectAction.Expand; node.ChildNodes.Add(newNode); } } } /// <summary> /// 填充末节点(学生列表) /// </summary> /// <param name="node"></param> private void PopulateStu(TreeNode node) { DataTable dt = RunQuery("PopulateStu", node.Value); if (dt.Rows.Count > 0) { foreach (DataRow row in dt.Rows) { TreeNode newNode = new TreeNode(); newNode.Text = row["姓名"].ToString(); newNode.Value = row["学号"].ToString(); //不设置动态填充节点 newNode.PopulateOnDemand = false; //设置选择该级节点时引发 SelectedNodeChanged 事件 newNode.SelectAction = TreeNodeSelectAction.Select; node.ChildNodes.Add(newNode); } } } /// <summary> /// 取得节点信息 /// </summary> /// <param name="QueryString">填充节点等级说明</param> /// <param name="nodeValue">筛选条件</param> /// <returns>查询结果</returns> private DataTable RunQuery(string QueryString, string nodeValue) { DataTable mytable = new DataTable(); if (QueryString == "PopulateDept") { mytable.Columns.Add("部门编号", typeof(string)); mytable.Columns.Add("部门名称", typeof(string)); //LINQ实体操作类，生成的 JWInfoDataContext db = new JWInfoDataContext(); var result = from dept in db.部门 select new { dept.部门编号, dept.部门名称 }; foreach (var item in result) { DataRow newRow = mytable.NewRow(); newRow["部门编号"] = item.部门编号.ToString(); newRow["部门名称"] = item.部门名称.ToString(); mytable.Rows.Add(newRow); } } else if (QueryString == "PopulateClassID") { mytable.Columns.Add("班级编号", typeof(string)); mytable.Columns.Add("班级名称", typeof(string)); JWInfoDataContext db = new JWInfoDataContext(); var reuslt = from Class in db.班级 where Class.部门编号 == nodeValue select new { Class.班级编号, Class.班级名称 }; foreach (var item in reuslt) { DataRow row = mytable.NewRow(); row["班级编号"] = item.班级编号.ToString(); row["班级名称"] = item.班级名称.ToString(); mytable.Rows.Add(row); } } else if (QueryString == "PopulateStu") { mytable.Columns.Add("学号", typeof(string)); mytable.Columns.Add("姓名", typeof(string)); JWInfoDataContext db = new JWInfoDataContext(); var result = from stu in db.学生信息 where stu.班级编号 == nodeValue select new { stu.学号, stu.姓名 }; foreach (var item in result) { DataRow row = mytable.NewRow(); row["学号"] = item.学号.ToString(); row["姓名"] = item.姓名.ToString(); mytable.Rows.Add(row); } } return mytable; } }