This class represents a validation control that is used to force user entry in a corresponding input control, like a TextBox. Validation fails if the value in the input control does not differ from the InitialValue property. By default, InitialValue is set to System.String.Empty and validation will succeed as long as some information has been added to the input control.

You can use a combination of different validation controls for a single control. For example, you could use a RequiredFieldValidator to ensure that a value is entered and a RangeValidator to ensure that the value is within a specified data range. This is often required, as validators like RangeValidator will automatically validate a control if it is empty, regardless of the properties you have set.

public class RequiredFieldValidator : BaseValidator {
// Public Constructors
   public RequiredFieldValidator( );
// Public Instance Properties
   public string InitialValue{set; get; }
// Protected Instance Methods
   protected override void AddAttributesToRender(System.Web.UI.HtmlTextWriter writer);// overrides BaseValidator
   protected override bool EvaluateIsValid( );                    // overrides BaseValidator
}

Hierarchy

System.Object System.Web.UI.Control(System.ComponentModel.IComponent, System.IDisposable, System.Web.UI.IParserAccessor, System.Web.UI.IDataBindingsAccessor) WebControl(System.Web.UI.IAttributeAccessor) Label BaseValidator(System.Web.UI.IValidator) RequiredFieldValidator