从GridView删除行，对象未设置为对象引用

Question

I am trying to delete row from Datagrid. I am using Ilist as a datasource. I already initialised IList object in DataGrid_Rowdeleting event but still same exception is harrasing me. Please help me out. My code is as below

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
using System.Data;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            IList lst = new ArrayList();
            Session["lst"] = lst;
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        Class1 c = new Class1();
        c.product = txtName.Text;
        c.quantity = txtQty.Text;
        IList lst = (IList)Session["lst"];
        lst.Add(c);
        GridView1.DataSource = lst;
        GridView1.DataBind();

    }
    protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
       DataTable dt = new DataTable();
       dt = (DataTable)GridView1.DataSource;
        dt.Rows.RemoveAt(e.RowIndex);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }

    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {

    }
}

Answer 1

Problem is here:

dt = (DataTable)GridView1.DataSource;

DataSource is not null only when set explicitly in previous steps of the page life cycle. In your case it was not set anywhere during postback (which was triggered by delete command), thus DataSource is null.

Correct way to handle this is to run necessary delete query in the DB, retrieve updated info and rebind the grid.

Answer 2

Try This one

protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
   IList lst = (IList)Session["lst"];
   lst .RemoveAt(e.RowIndex);
    GridView1.DataSource = lst ;
    GridView1.DataBind();
}