DataGrid的模板列可以方便的定制所需要的样式，比如上图：
在编辑状态的时候学院是下拉框，选择了当前的学院，但是如果学院很多，下拉框会很长，找起来也会很麻烦，所以可能需要再增加一个查找的功能。这样一个列完全可以通过模板列来实现，可是如果项目中有很多这样的需求，添加这么多复杂的模板列一来很麻烦，二来也有代码冗余，没有重用性，为此，我们可以尝试定制自己的DataGridColumn（类似已经存在的HyperLinkColumn）来为这个列进行小小的封装。
先建立一个类文件：
using System;using System.Data;using System.Web.UI;using System.Web.UI.WebControls;namespace csdn
{
public class MyColumn:DataGridColumn
{ public string DataTextField; public string DataValueField; public DataTable DataSource; public override void InitializeCell(TableCell cell,int columnIndex,ListItemType itemType) { base.InitializeCell(cell,columnIndex,itemType); switch(itemType) { case ListItemType.Header: cell.Text=this.HeaderText; break; case ListItemType.Item:case ListItemType.AlternatingItem: cell.DataBinding+=new EventHandler(this.cell_ItemDataBinding); break; case ListItemType.EditItem: cell.DataBinding +=new EventHandler(cell_EditItemDataBinding); DropDownList ddl=new DropDownList(); cell.Controls.Add(ddl); TextBox t=new TextBox(); t.Width=80; cell.Controls.Add(t); Button b=new Button(); b.Text="查找"; b.Click+=new EventHandler(this.btn_Click); cell.Controls.Add(b); break;
} } private void cell_ItemDataBinding(object sender, EventArgs e) { TableCell cell=(TableCell)sender; DataGridItem dgi=(DataGridItem)cell.NamingContainer; cell.Text=(DataBinder.Eval(dgi.DataItem,this.DataTextField)).ToString(); } private void cell_EditItemDataBinding(object sender,EventArgs e) { TableCell cell=(TableCell)sender; DropDownList ddl=(DropDownList)cell.Controls[0]; DataGridItem dgi=(DataGridItem)cell.NamingContainer; for(int i=0;i<this.DataSource.Rows.Count;i++) ddl.Items.Add(new ListItem(this.DataSource.Rows[i][this.DataTextField].ToString(),this.DataSource.Rows[i][this.DataValueField].ToString())); ddl.Items.FindByValue((DataBinder.Eval(dgi.DataItem,this.DataValueField)).ToString()).Selected=true; } private void btn_Click(object sender,EventArgs e) { TableCell cell=(TableCell)(((Button)sender).Parent); DropDownList ddl=(DropDownList)cell.Controls[0]; TextBox t=(TextBox)cell.Controls[1]; DataGridItem dgi=(DataGridItem)cell.NamingContainer; ListItem li=ddl.Items.FindByText(t.Text); if(li!=null) { ddl.SelectedIndex=-1; li.Selected=true; } } }
}
然后为页面添加这个自定义列：
<%@ Page language="c#" Codebehind="WebForm67.aspx.cs" AutoEventWireup="false" Inherits="csdn.WebForm67" %><%@ Register TagPrefix="MyDataGridColumn" Assembly="csdn" NameSpace="csdn"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" ><HTML> <HEAD> <title>Test</title> <META http-equiv="Content-Type" content="text/html; charset=gb2312"> <meta content="Microsoft Visual Studio .NET 7.1" name="GENERATOR"> <meta content="C#" name="CODE_LANGUAGE"> <meta content="JavaScript" name="vs_defaultClientScript"> <meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema"> <LINK href="css.css" type="text/css" rel="stylesheet"> </HEAD> <body> <form id="Form1" method="post" runat="server"> <asp:datagrid id="DataGrid1" runat="server" DataKeyField="stuid" CellSpacing="1" BorderWidth="0px" OnEditCommand="edit" OnCancelCommand="cancel" OnUpdateCommand="update" CellPadding="5" CssClass="border" AutoGenerateColumns="False"> <ItemStyle CssClass="item"></ItemStyle> <HeaderStyle CssClass="header"></HeaderStyle> <Columns> <asp:BoundColumn HeaderText="姓名" DataField="stuname"></asp:BoundColumn> <MyDataGridColumn:MyColumn HeaderText="学院" DataTextField="depname" DataValueField="depid"></MyDataGridColumn:MyColumn> <asp:EditCommandColumn ButtonType="PushButton" UpdateText="更新" CancelText="取消" EditText="编辑"></asp:EditCommandColumn> </Columns> </asp:datagrid> </form> </body></HTML>
后台代码如下：
using System;using System.Collections;using System.ComponentModel;using System.Data;using System.Data.SqlClient;using System.Drawing;using System.Web;using System.Web.SessionState;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.HtmlControls;namespace csdn{ /**//// <summary> /// WebForm67 的摘要说明。 /// </summary> public class WebForm67 : System.Web.UI.Page { protected System.Web.UI.WebControls.DataGrid DataGrid1; private void Page_Load(object sender, System.EventArgs e) { // 在此处放置用户代码以初始化页面 if(!IsPostBack) { SetBind(); } } protected void SetBind() { SqlConnection conn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["conn"]); SqlDataAdapter da=new SqlDataAdapter("select * from stu,dep where stu.studepid=dep.depid",conn); DataSet ds=new DataSet(); da.Fill(ds); this.DataGrid1.DataSource=ds.Tables[0]; this.DataGrid1.DataBind(); } protected void edit(object sender,DataGridCommandEventArgs e) { this.DataGrid1.EditItemIndex=e.Item.ItemIndex; SetBind(); } protected void cancel(object sender,DataGridCommandEventArgs e) { this.DataGrid1.EditItemIndex=-1; SetBind(); } protected void update(object sender,DataGridCommandEventArgs e) { if(e.Item.ItemType==ListItemType.EditItem) { SqlConnection conn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["conn"]); SqlCommand comm