Question

我有一个GridView，它包含一个下拉列表。我有一个列表，希望将此列表绑定到gridview中的下拉列表。

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"OnSelectedIndexChanged="GridView1_SelectedIndexChanged" OnRowDataBound="GridView1_RowDataBound">
        <Columns>
<ItemTemplate>
                    <asp:Label ID="Label2" runat="server"></asp:Label>
                    <asp:DropDownList ID="DropDownList3" runat="server" AppendDataBoundItems="True" OnSelectedIndexChanged="DropDownList3_SelectedIndexChanged1"  >

                    </asp:DropDownList>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>

和

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        DropDownList dropdown = (DropDownList)e.Row.FindControl("DropDownList3");
        ClassDal obj = new ClassDal();
        List<phone> list = obj.GetAll();
        dropdown.DataTextField = "phone";
        dropdown.DataValueField = "id";
        dropdown.DataSource = list.ToList();
        dropdown.DataBind();

    }

和

namespace sample_table
{
public class ClassDal
{
    public List<phone> GetAll()
    {
        using (PracticeDBEntities1 context = new PracticeDBEntities1())
        {
            return context.phone.ToList();
        }
    }
}
}

但是我收到了这个例外：对象引用未设置为对象的实例在行上：dropdown.DataTextField =＆＃34; phone＆＃34 ;;

Answer 1

在RowType事件处理程序中加入RowDataBound检查。

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if(e.Row.RowType == DataControlRowType.DataRow)
    {
        DropDownList dropdown = (DropDownList)e.Row.FindControl("DropDownList3");
        ClassDal obj = new ClassDal();
        List<phone> list = obj.GetAll();
        dropdown.DataTextField = "phone";
        dropdown.DataValueField = "id";
        dropdown.DataSource = list.ToList();  // <- why are you doing list.ToList()?
        dropdown.DataBind();
    }

}

Answer 2

您的问题将得到解决，只需将数据源置于文本字段之前，如下所示

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        DropDownList dropdown = (DropDownList)e.Row.FindControl("DropDownList3");
        ClassDal obj = new ClassDal();
        List<phone> list = obj.GetAll();
        dropdown.DataSource = list.ToList();
        dropdown.DataTextField = "phone";
        dropdown.DataValueField = "id";
         dropdown.DataBind();

    }

如何将列表绑定到gridview中的下拉列表

2 个答案: