Form validating event
One of the features of HTML5 is the ability to validate most user data without relying on scripts.This is done by using validation attributes on form elements.For more information beyond this tutorial, see the Constraint validation guide. When you enter data, the web application checks it to see that the data is correct.
private: void text Box1_Validating( Object^ sender, System:: Component Model:: Cancel Event Args^ e ) void text Box1_Validated( Object^ sender, System:: Event Args^ e ) public: bool Valid Email Address( String^ email Address, [Out]interior_ptrprivate void text Box1_Validating(object sender, System. Cancel Event Args e) private void text Box1_Validated(object sender, System. Length = 0 Then error Message = "Email address is required." Return False End If ' Confirm that there is an "@" and a "." in the email address, and in the correct order. Cr _ "For example '[email protected]' " Return False End Function Private Sub text Box1_Validating(By Val sender As Object, _ By Val e As System. Text, error Msg) Then ' Cancel the event and select the text to be corrected by the user.
Let's see how to use this API to build custom error messages.
First, the HTML: attribute to turn off the browser's automatic validation; this lets our script take control over validation.
The following code example uses the derived class Text Box and validates an email address that the user enters. Length) ' Set the Error Provider error with the text to display. Set Error(text Box1, error Msg) End If End Sub Private Sub text Box1_Validated(By Val sender As Object, _ By Val e As System. Validated ' If all conditions have been met, clear the error provider of errors. Set Error(text Box1, "") End Sub When you change the focus by using the keyboard (TAB, SHIFT TAB, and so on), by calling the Select or Select Next Control methods, or by setting the Container Control.
If the email address is not in the standard format (containing "@" and "."), the validation fails, an Error Provider icon is displayed, and the event is canceled. Active Control property to the current form, focus events occur in the following order: Caution Do not attempt to set focus from within the Enter, Got Focus, Leave, Lost Focus, Validating, or Validated event handlers.