Error checking length of data entered in a web form

SouthendSupporter · March 26th, 2010, 11:19 AM

Hi
I have a web form requesting information regarding a business. One of the fields is Business Description which may not exceed 1500 characters.

My page starts like this:

Code:

<%@ Page Title="" Language="VB" MasterPageFile="~/MasterPages/ManagementMaster.master" AutoEventWireup="false" CodeFile="Members_AddEdit.aspx.vb" Inherits="Management_Members_AddEdit" %>

<%@ Register Assembly="System.Web.DynamicData, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
  Namespace="System.Web.DynamicData" TagPrefix="cc1" %>
  
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="cpmainContent" Runat="Server">
 <script type="text/javascript">
   function ClValidateText(oSrc, args) 
   {
     var txtDesc = document.getElementById('<%= tbBusDesc.ClientID %>');

     if (txtDesc.value.length == 10) 
     {
       args.IsValid = 'true'
     }
     else
     {
       args.IsValid = 'False'
     }
   }
</script>

The Details View entries for the field are:

Code:

<EditItemTemplate>
          <asp:TextBox ID="tbBusDesc" runat="server" type="multiline" Width="500" Height="100" Text='<%# Bind("BusinessDescription") %>' ></asp:TextBox>
          <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ErrorMessage="Please enter a description of the business" ControlToValidate="tbBusDesc" Text="*"></asp:RequiredFieldValidator>
          <asp:CustomValidator ID="CustomValidator1" runat="server" ErrorMessage="Business Description Exceeds 1500 characters" ControlToValidate="tbBusDesc1" Text="*" OnServervalidate="ValidateText10" Display="Dynamic" ></asp:CustomValidator>
        </EditItemTemplate>
        <InsertItemTemplate>
          <asp:TextBox ID="tbBusDesc" runat="server" type="multiline" Width="500" Height="100" Text='<%# Bind("BusinessDescription") %>' TextMode="MultiLine"></asp:TextBox>
          <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ErrorMessage="Please enter a description of the business" ControlToValidate="tbBusDesc" Text="*"></asp:RequiredFieldValidator>
          <asp:CustomValidator ID="CustomValidator2" runat="server" ErrorMessage="Business Description Exceeds 1500 characters" ControlToValidate="tbBusDesc2" Text="*" OnServerValidate="ValidateText10" ClientValidationFunction="ClValidateText"></asp:CustomValidator>       
        </InsertItemTemplate>

The server side check works fine:

Code:

    Protected Sub ValidateText10(ByVal source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs)
        args.IsValid = args.Value.Length <= 1500
    End Sub

(before I added the script for client side checking)
When I try build the page in VS (using ctlF5) I get build errors referencing Line1 and Line 12

Code:

var txtDesc = document.getElementById('<%= tbBusDesc.ClientID  %>');

Name tbBusDesc is not declared.
Presumably missing something simple but cannot see what :(

Lee Dumond · March 26th, 2010, 12:38 PM

I presume it is because tbBusDesc is embedded inside a template, which means you cannot access it directly using <%= tbBusDesc.ClientID %>.

Generally, you need to use the FindControl method to access controls inside of templates.