By simply using the four ASP.NET validation Web controls (the RequiredFieldValidator, the CompareValidator, the RangeValidator, and the
RegularExpressionValidator), we are able to solve the vast majority of our form validation needs. However, there may be times when we need
to perform more complex , more conditional validation logic.In such cases CUSTOM VALIDATOR comes into picture.
Building a simple CustomValidator Control
The below code shows a simple Web form with a text box, a checkbox and a button. if the checkbox is checked , the textbox should not be
empty and if it is unchecked the textbox can be empty. We are providing client side validation for this .
| <script type="text/javascript"> //function for checking the validation function CheckEmpty(sender, args) { var check=document.getElementById("CheckBox1"); if(check.checked==true) { if(args.Value=="") { args.IsValid =false; } else args.IsValid = true; } } </script> </head> <body> <form id="form1" runat="server"> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> <asp:CheckBox ID="CheckBox1" runat="server" /> <%-- custom validator--%> <asp:CustomValidator runat="server" id="custPrimeCheck" ControlToValidate="TextBox1" ValidateEmptyText="true" ClientValidationFunction="CheckEmpty" ErrorMessage="Please enter some data" /> <asp:button ID="Button1" runat="server" text="Button" /> </form> </body> </html> |
| |
The args parameter passed in the CheckEmpty() function contains two properties that are vitally important:
Value - indicates the value of the form field the CustomValidator control is validating.
IsValid - a Boolean property , Set IsValid to true if the Value is valid, false otherwise.
We can also perform server side validation using Custom validators.
Thanks & Regards,
Arun Manglick
SMTS || Microsoft Technology Practice || Bridgestone - Tyre Link || Persistent Systems || 3023-6258
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