I need Help Please just read

ysfkay · #1 (**permalink**) March 18th, 2009, 01:48 PM

I am a rookie programmer,
I am trying to create a requiredfield validator using the custom control available in .Net. I know about the inbuilt validators, but the case is that I need to create custom server side validators, therefore I dont want to mix the inbuilt client side validation controls that come with dotnet and the custom server side validators that I need to build. This is why I need to create a custom serverside textbox required field validator. But all efforts failed.THis is what I tried.

protected void e_serverValidate(................................. ... args)
{
if(TextBox1.Text.Trim()=="")
args.IsValid=false;
else
args.isValid=true;
}
Please how am I suppose to write the appriopriate code . Csharp, thank you

Lee Dumond · #2 (**permalink**) March 18th, 2009, 02:02 PM

You are aware that the standard validators do validate on the server side as well as the client side, yes? And that you can turn the client-side validation off?

As far as I know, you cannot use the CustomValidator on non-existent input. In other words, if the input is empty, the custom validation method never fires. Therefore, I don't see how you can use custom server-side validation to validate if a field is empty or not.

ysfkay · #3 (**permalink**) March 20th, 2009, 03:29 PM

Thanks that what I needed to hear that if the field is empty then the validation is not triggered, cuz I started to suspect that after trying all that I could think of,but you said that the standard validators also validate on the serverside, so how can I make like the standard required field validator validate on the server side instead of on the client side?

Lee Dumond · #4 (**permalink**) March 20th, 2009, 03:43 PM

Quote:

Originally Posted by ysfkay

but you said that the standard validators also validate on the serverside, so how can I make like the standard required field validator validate on the server side instead of on the client side?

You do not have to do anything special to enable server side validation. All of the standard validators validate on both the server side and client side by default.

You can optionally turn the client side validation off. However, you cannot turn the server side validation off. The server side validation always fires. (The actual method that performs the validation is part of the .NET source code.)

Of course, you should check the value of the IsValid property of the page in any methods you execute on postback.

Lee Dumond · #5 (**permalink**) March 20th, 2009, 06:11 PM

By the way, in case you are interested in how server-side validation works behind the scenes:

When the page is validated, it triggers the Validate method on all of the validation controls on the page. The Validate method is part of the IValidator implementation of BaseValidator.

The Validate method in turn calls the EvaluateIsValid method, which is an abstract method which is overridden in any control that inherits BaseValidator. The following code shows the override from the RequiredFieldValidator class:

Code:

protected override bool EvaluateIsValid()
{
    string controlValidationValue = base.GetControlValidationValue(base.ControlToValidate);
    return ((controlValidationValue == null) || !controlValidationValue.Trim().Equals(this.InitialValue.Trim()));
}

As you can see, it returns true if there is a non-null value for the control that is being validated.

Again, this is all performed on the server side and is built-in functionality.

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