ASP.NET GridView - Add a new record

最新推荐文章于 2025-07-18 11:21:58 发布

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本文介绍了一种在ASP.NET GridView中实现插入功能的方法，并解决了当数据源为空时不显示的问题。通过简单的代码修改，在Grid顶部预置空白行，用作新记录的编辑行。

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Introduction

This code drop is part of a Smash and Grab series for the seriously ADD (Attention Deficit Disorder) programmer. I'll bet there are a lot of other programmers out there who would like to make code available to others, but just don't want to spend the hours required to create a full-blown "CodeProject" article. This is an attempt to see if I can make some useful code available to other programmers, and do it in 10 minutes. I encourage others to contribute to "Smash and Grab".

The point of this series is to present usable pre-canned classes or techniques which solve a real world problem without going into too much detail about how it works. I mean, who really cares about how System.Collections.ArrayList works, you just use it.

Please fully comment the code so that the person who really cares (and has the time) will be able to understand the underlying algorithm.

Using the code

There has been a lot of whining on the net about what a train-wreck the ASP.NET 2.0 GridView is because it won't do inserts and if the table source is empty, the grid does not even render.

Here is a solution in less than 15 lines of code.

Create a GridView as usual (I am using the NorthWind Categories table as an example).
Create the data source.

Change:

SelectCommand="SELECT [CategoryID], [CategoryName]," + 
            " convert(nvarchar(1000),[Description]) FROM [Categories]";

to:

SelectCommand="SELECT '' as [CategoryID], '' as [CategoryName]," + 
         " '' as [Description] UNION SELECT [CategoryID]," + 
         " [CategoryName], convert(nvarchar(1000),[Description])" + 
         " FROM [Categories]";

This inserts a blank row as the first line of the grid.

This is the line that you will be editing to add the new record.

Add:
```
OnRowUpdating="GridView1_RowAdding";
```
as an event to the grid (you can do it through the GUI).
Add the highlighted JavaScript code.
It finds the first "Edit Delete" text and changes it to "Add".
Add the "GridView1_RowAdding" method.

OnRowUpdating is called by the GridView before it updates a row. The GridView thinks it is doing an update to CategoryID=0 (which will silently fail). Meanwhile, you are scooping the data and doing a secret insert.

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<%@ Page Language="C#" AutoEventWireup="true" 
             CodeFile="AddUpdate.aspx.cs" Inherits="AddUpdate" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
    <script>
    function FixGrid(idGrid)
    {
      // content looks like:
      //"<A href=/"javascript:__doPostBack('GridView1',
      //    'Edit$0')/">Edit</A> 
      // <A href=/"javascript:__doPostBack('GridView1',
      //    'Delete$0')/">Delete</A>"
      // replace Edit with Add, remove Delete
      var Parts = 
       idGrid.firstChild.childNodes[1].childNodes[0].innerHTML.split(">Edit<");
      var tmp = Parts.join(">Add<"); 
      Parts = tmp.split(">Delete<");
      idGrid.firstChild.childNodes[1].childNodes[0].innerHTML = 
                                        Parts.join("><");
    }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server" 
                 AutoGenerateColumns="False" DataKeyNames="CategoryID"
            DataSourceID="SqlDataSource1" 
                    OnRowUpdating="GridView1_RowAdding">
            <Columns>
                <asp:CommandField ShowDeleteButton="True" 
                    ShowEditButton="True" />
                <asp:BoundField DataField="CategoryID" 
                    HeaderText="CategoryID" InsertVisible="False"
                    ReadOnly="True" SortExpression="CategoryID" />
                <asp:BoundField DataField="CategoryName" 
                       HeaderText="CategoryName" 
                       SortExpression="CategoryName" />
                <asp:BoundField DataField="Description" 
                       HeaderText="Description" 
                       SortExpression="Description" />
            </Columns>
        </asp:GridView>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
              ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
            DeleteCommand="DELETE FROM [Categories] 
                           WHERE [CategoryID] = @CategoryID"
            InsertCommand="INSERT INTO [Categories] 
                           ([CategoryName], [Description]) 
                           VALUES (@CategoryName, @Description)"
            SelectCommand="SELECT '' as [CategoryID], 
                '' as [CategoryName], '' as [Description]
                UNION SELECT [CategoryID], [CategoryName], 
                convert(nvarchar(1000),[Description])
                FROM [Categories]" 
            UpdateCommand="UPDATE [Categories] SET 
                           [CategoryName] = @CategoryName, 
                           [Description] = @Description 
                           WHERE [CategoryID] = @CategoryID">
            <DeleteParameters>
                <asp:Parameter Name="CategoryID" Type="Int32" />
            </DeleteParameters>
            <UpdateParameters>
                <asp:Parameter Name="CategoryName" Type="String" />
                <asp:Parameter Name="Description" Type="String" />
                <asp:Parameter Name="CategoryID" Type="Int32" />
            </UpdateParameters>
            <InsertParameters>
                <asp:Parameter Name="CategoryName" Type="String" />
                <asp:Parameter Name="Description" Type="String" />
            </InsertParameters>
        </asp:SqlDataSource>
    
    </div>
    </form>
        <script>
            FixGrid(document.all.GridView1);
        </script>
</body>
</html>

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using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class AddUpdate : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void GridView1_RowAdding(object sender, 
                        GridViewUpdateEventArgs e)
    {
        if (e.RowIndex > 0)
            return; // RowIndex=0 is the row we want to insert
        System.Collections.Hashtable h = 
                    new System.Collections.Hashtable();

        foreach (System.Collections.DictionaryEntry x in e.NewValues)
        {
            h[x.Key] = x.Value;
        }
        // you now have the data to insert in a hashtable
        // get it into the database using your
        // usual Data Access Layer methods

    }
}