Question

这是我的标记视图

    <body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" OnRowDataBound="GridView1_RowDataBound" DataKeyNames="SemesterID" DataSourceID="SqlDataSource1" >
            <Columns>
                <asp:BoundField DataField="SemesterID" HeaderText="SemesterID" InsertVisible="False" ReadOnly="True" SortExpression="SemesterID" />
                <asp:BoundField DataField="SemesterName" HeaderText="SemesterName" SortExpression="SemesterName" />
<asp:TemplateField>
                    <asp:PlaceHolder ID="pHldr" runat="server"></asp:PlaceHolder>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>
    </div>
        <asp:SqlDataSource ConnectionString="<%$ connectionStrings:MyConnection %>" ID="SqlDataSource1" runat="server" ProviderName="System.Data.SqlClient" SelectCommand="SELECT SemesterID, SemesterName FROM Semesters"></asp:SqlDataSource>
    </form>
</body>

这是我的代码behinde文件

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        for (int i = 0; i < 3; i++)
        {
            PlaceHolder plHldr = e.Row.FindControl("pHldr") as PlaceHolder;
            CheckBox cbx = new CheckBox();

            plHldr.Controls.Add(cbx);//Here I get the exception
        }
    }

我想在PlaceHolder中添加复选框等控件，但我在plHldr.Controls.Add(cbx);

中得到NullReferenceException

Answer 1

可能是因为你没有对第一行（行索引-1）进行处理，这是标题。尝试使用e.Row.RowIndex确保您没有尝试从标题行转换控件：

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowIndex < 0) return;

    for (int i = 0; i < 3; i++)
    {
        PlaceHolder plHldr = e.Row.FindControl("pHldr") as PlaceHolder;
        CheckBox cbx = new CheckBox();

        plHldr.Controls.Add(cbx);//Here I get the exception
    }
}

NullReferenceExecption在gridview的DataBound上添加控件时

1 个答案: