无法批量删除

Question

  前台：
<asp:GridView ID="GridView2" runat="server" AllowPaging="True" AutoGenerateColumns="False"
            DataKeyNames="id"  Width="661px">
            <Columns>
                <asp:BoundField DataField="id" HeaderText="id" InsertVisible="False" ReadOnly="True"
                    SortExpression="id" />
                <asp:BoundField DataField="title" HeaderText="title" SortExpression="title" />
                <asp:TemplateField HeaderText="删除" >
                <ItemTemplate>
                <asp:CheckBox ID="chk" runat="server"/>
                </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>
<br />
        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="选中并删除" />
后台： protected void Button1_Click(object sender, EventArgs e)
    {
        string sqlText = "(";
        string str = "select * from news";
        for (int i = 0; i < GridView2.Rows.Count; i++)
        {
            //搜索第n行3列 
            CheckBox cbx = (CheckBox)GridView1.Rows[i].FindControl("chk");
            if (cbx.Checked==true)
            {
                sqlText = sqlText + Convert.ToInt32(GridView2.DataKeys[i].Value) + ",";
            }
        }
        //去掉最后的逗号，并且加上右括号 
        sqlText = sqlText.Substring(0, sqlText.Length - 1) + ")";
        sqlText = "delete news where id in" + sqlText;
        try
        {
            //执行删除语句 
            SqlConnection conn = yjdbclass.opennconn();
            conn.Open();
            SqlCommand cmd = new SqlCommand(sqlText, conn);
            int delCount = Convert.ToInt32(cmd.ExecuteNonQuery());
            Response.Write("<script>alert('共删除" + delCount + "条数据');</script>");
            yjdbclass.gridview(str, this.GridView2);
        }
        catch (Exception ex)
        {
            //若有错误发生，输出错误信息 
            Response.Write(ex.Message);
        } 
        finally
        {
            yjdbclass.gridview(str,this.GridView2);
        }    }出错：
if (cbx.Checked==true)      //未将对象引用设置到对象实例

Answer 1

CheckBox cbx = (CheckBox)GridView1.Rows[i].FindControl("chk"); 
改成
CheckBox cbx = new CheckBox();
cbx = (CheckBox)GridView1.Rows[i].FindControl("chk"); 

Answer 2

CheckBox cbx = (CheckBox)GridView1.Rows[i].FindControl("chk"); 
这句话并没能够找到该checkbox控件，因此cbx为null
因此cbx.Checked才会报“未将对象引用设置到对象实例”错误

Answer 3

一楼的这样改还不是一样~~~~
faint~~~

Answer 4

给你改一下for (int i = 0; i <= GridView2.Rows.Count - 1; i++)
        {
            CheckBox cbx = (CheckBox)GridView1.Rows[i].FindControl("chk"); 
            if (cbx .Checked == true)
            {
//这里 你继续            }
        }

Answer 5

对不起没有仔细看
是你循环的问题，GridView2.Rows.Count-1就对了

Answer 6

for (int i = 0; i < GridView2.Rows.Count; i++) 
        { 
}
我这样做没问题
if( (CheckBox)GridView1.Rows[i].FindControl("chk").checked)