Question

当我更改下拉列表的选定值时，我正在尝试填充ID为O1IDText的文本框。我收到错误＆＃34;对象引用没有设置为对象的实例＆＃34;。

以下是我在ASP下拉列表中的代码：

<EditItemTemplate>
    <asp:DropDownList ID="DropDownList1" AutoPostBack="true" runat="server" DataSourceID="SqlDataSource2" AppendDataBoundItems="true" OnDataBinding="DropDownlist1_DataBinding1" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" DataTextField="FullName" DataValueField="FullName" SelectedValue='<%# Bind("Official1") %>'>
    </asp:DropDownList>
</EditItemTemplate>

以下是我Textbox wihtin ASP的代码：

<EditItemTemplate>
    <asp:TextBox ID="O1IDText" runat="server" Text='<%# Bind("O1ID") %>'></asp:TextBox>
</EditItemTemplate>

最后我的代码落后于VB：

Protected Sub DropDownList1_SelectedIndexChanged(sender As Object, e As EventArgs)


    Dim ddList As DropDownList = CType(sender, DropDownList)
    RemoveHandler ddList.DataBinding, AddressOf DropDownlist1_DataBinding1
    Dim O1IDText As TextBox = TryCast(FindControl("O1IDText"), TextBox)


    Dim cmd As SqlCommand = con.CreateCommand()
    cmd.CommandType = System.Data.CommandType.Text
    cmd.CommandText = "Select ID from Official where [First Name] + ' ' + [Last Name]+ ' ' +[Email]+ ' ' +[Phone] = '" + ddList.SelectedValue + "'"
    Dim dr As SqlDataReader


    Try
        con.Open()
        dr = cmd.ExecuteReader()
        dr.Read()
        O1IDText.Text = dr("ID").ToString

    Catch ex As Exception
        con.Close()
    End Try

异常＆＃34;对象引用未设置为对象的实例＆＃34;在O1IDText.Text = dr("ID").ToString期间发生。

Answer 1

假设DropDownList和TextBox都在同一行或项目中，您可以这样获取TextBox：

Dim O1DText As TextBox = CType(ddList.NamingContainer.FindControl("O1DText"), TextBox)

使用数据库

1 个答案: