Validation Controls

Bryan Xu

ASP.NET supplies 6 different validation controls, each with some distinct properties besides the few common ones:

  • RequiredFieldValidator
  • RangeValidator
    • MaximumValue (In code behind, MaximumValue=DateTime.Today.ToString(“yyyy/MM/dd”))
    • MinimumValue (1850/1/1)
    • Type (String or Date)
  • RegularExpressionValidator
    • ValidationExpression – put in regular expression here. There are a few of pre-defined ones.
  • CompareValidator
    • ControlToValidate & ControlToCompare
  • CustomValidator
    • Double-click on design mode to get the event handler on server-side
      e.g. args.IsValid == (args.Value.Length >= 8 )
    • clientValidationFunction (JavaScript)
      e.g.
      function isLengthValid (source, args)
      {
      args.IsValid = (args.Value.Length >= 8 )
      }
    • Both client- and server-side validation function should be included
  • ValidationSummary
    • HeaderText
    • CssClass
    • DisplayMode
  • Common properties:
    • ControlToValidate – this is the most essential obvisouly, a must
    • ErrorMessage – Text in here will be displayed in the ValidationSummary
    • Text – This will be displayed right at where the validation control lies
    • Display (Static/Dynamic/None) – pretty intuitive. I see “dynamic” being the default, because it doesn’t take up space when it’s not being validated. There is no reason for some empty place holder.
    • EnableClientScript – default is true; if browser supports JavaScript, then validation is done on client first. If the validation fails, then postback is cancelled.
    • ValidationGroup – Just give it a name, and give the same name to the button or whatever control that is to trigger the validation, then only the fields with the same group name will be validated.
      Uses:
      Page.Validate(ValidationGroupPropertyValue) – tells the page to perform validation on fields with that specified validation group
      GetValidators(ValidationGroup) – returns a collection of validation controls that belong to the specified validation group
    • SetFocusOnError – same as the Focus() method; if set to True, causes the Web control the validation control is operating on to receive focus if the validation control is invalid

Example: To validate a password, should use the following validation

  • RequiredFieldValidator
  • RegularExpressionValidator
  • CompareValidator (for the re-type password field)
  • CustomValidator (To check length of password)

More references:

By Bryan Xu