Conditional validation

I have an ASP.NET web app (with C#). In it I have a form with several fields and 开发者_如何转开发validators. For one of the validators I only need to validate when:

• a certain textbox is empty
• and a certain record does not exist in the database (this is already handled).

I know I can't enable/disable the validator on page_load because something might be entered into that textbox. I also tried the following in the onclick event of the submit button but it didn't seem to work:

                    Validator1.Enabled = true;
                    Validator1.Validate();

I also tried Page.Validate() but that didn't work either...

Can anyone please help?

Thanks

Use a customvalidator. Inside the Validation Event you have code like this pseudo code:

OnValidating(object sender, ServerValidateEventArgs e)
{
 if(CertainTextBox.Text.IsNullOrEmpty() && CertainRecordDoesNotExistInDB))
{
 // validate
// and set e.Valid to the desired validation output
}
else
{
 e.IsValid = false;
}
}

this things should be done by JavaScript on client. Then on submit you should validate at server side.