FindControl返回Null

Question

我试图根据相关的文本框控制按钮状态.名称与前缀不同.文本框和按钮位于页面上的表格中.

<asp:Table ID="Table1" runat="server" CssClass="table">
            <asp:TableRow>
                <asp:TableCell Width="15%">
                    <asp:Label ID="lblRequestHeader" runat="server" Text="Requested" CssClass="bold text-center"
                        Width="90%"></asp:Label>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:Label ID="lblApprovalHeader" runat="server" Text="Approval" CssClass="bold text-center"
                        Width="90%"></asp:Label>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:Label ID="lblApprovalTimeHeader" runat="server" Text="Date/Time of Approval"
                        CssClass="bold text-center" Width="90%"></asp:Label>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:Label ID="lblReadyHeader" runat="server" Text="Ready To Pick Up" CssClass="bold text-center"
                        Width="90%"></asp:Label>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:Label ID="lblCollectedHeader" runat="server" Text="Collected By TestHouse" CssClass="bold text-center"
                        Width="90%"></asp:Label>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:Label ID="lblDeliveredHeader" runat="server" Text="Delivered From TestHouse"
                        CssClass="bold text-center" Width="90%"></asp:Label>
                </asp:TableCell>
            </asp:TableRow>
            <asp:TableRow>
                <asp:TableCell Width="15%">
                    <asp:TextBox ID="txtRequestTime" runat="server" Width="90%"> </asp:TextBox>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:TextBox ID="txtApproval" runat="server" Width="90%"></asp:TextBox>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:TextBox ID="txtApprovalTime" runat="server" Width="90%"></asp:TextBox>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:TextBox ID="txtReadyTime" runat="server" Width="90%"></asp:TextBox>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:TextBox ID="txtCollectedTime" runat="server" Width="90%"></asp:TextBox>
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:TextBox ID="txtDeliveredTime" runat="server" Width="90%"></asp:TextBox>
                </asp:TableCell>
            </asp:TableRow>
            <asp:TableRow>
                <asp:TableCell Width="15%">
                </asp:TableCell>
                <asp:TableCell Width="15%">
                </asp:TableCell>
                <asp:TableCell Width="15%">
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:Button ID="btnReadyTime" runat="server" Text="Ready To Collect" Width="90%" />
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:Button ID="btnCollectedTime" runat="server" Text="Collected" Width="90%" />
                </asp:TableCell>
                <asp:TableCell Width="15%">
                    <asp:Button ID="btnDeliveredTime" runat="server" Text="Delivered" Width="90%" />
                </asp:TableCell>
            </asp:TableRow>
        </asp:Table>

文本框由dataretrieval填充,然后按下调用方法设置按钮的状态,如下所示:

txtReadyTime.Text = slabdetails.ReadyTimestamp.ToString();
textboxenabled(txtReadyTime);

此方法将文本框名称修改为按钮名称,然后尝试查找按钮以启用/禁用它.

 public void textboxenabled(TextBox box)
    {
       string btnName = box.ID.Replace("txt", "btn");
        try
        {
            Button btn = FindControl(btnName) as Button;
            if (box.Text == "")
                btn.Enabled = true;
            else
                btn.Enabled = false;
        }
        catch
        {
        }
    }

但是,尽管字符串完全匹配按钮的名称,控件仍返回null.可以采取哪些措施来解决这个问题？

Answer 1

感谢Matthew Watson,FindControl在使用母版页的项目中存在问题.要在页面中查找控件,必须先手动浏览母版页及其内容:

这个:

  Button btn = FindControl(btnName) as Button;

必须采取以下格式:

  Button btn = this.Master.FindControl("MainContent").FindControl(btnName) as Button;