Validation using the Validating TextBox
Use this information to help you configure a Validating TextBox control.
The Validating TextBox control has all the usual TextBox properties with additional IsValid and InvalidText properties. The IsValid property is typically configured with an expression. The expression must evaluate to true for the value to be considered valid.
The InvalidText property is used to specify the tooltip text to display when the value entered in the text box is invalid.
When the data entry does not meet the validation specification, the text box outlined in red and a tooltip is displayed, indicating the error.The following illustration provides an example.