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Regex Validation

This feature is supported only by the RadMaskedTextInput control.

RadMaskedTextInput allows you to enable an additional validation rule by defining a regular experession. The regex is applied over the value received after the Mask property validates the entered text.

Setting Regular Expression

The regex can be set via the ValidationRegex property of the RadMaskedTextInput control.

Example 1: Setting regex validation

<telerik:RadMaskedTextInput Mask="a20"                                     
                            maskedInput:ValidationHelper.DisplayValidationErrors="True"  />      

Example 1 shows how to restrict the user to enter only a valid email address with a maximum text length of 20 alphanumeric or special characters.

Take the ValueMode property into account when composing the regular expression. Depending on the mode the Value of the control might contain placeholders and literals.

Predefined Regular Expressions

The validation feature provides few predefined regular expressions that can be used.

  • Email: This expression allows you to validate email addresses.
  • IP: This expression allows you to validate IP addresses.

You can access the predefined regular expressions via the ValidationHelper class. It exposes the regexes via static readonly properties.

The ValidationHelper class can be found in the following namespace: xmlns:maskedInput="clr-namespace:Telerik.Windows.Controls.MaskedInput;assembly=Telerik.Windows.Controls.Input"

Example 2: Setting predefined regex in XAML

<telerik:RadMaskedTextInput ValidationRegex="{x:Static maskedInput:ValidationHelper.Email}" />       

Example 3: Setting predefined regex in code

this.maskedTextInput.ValidationRegex = ValidationHelper.Email; 

Set Error Message

You can set the error that will be shown in the validation tooltip via the ErrorMessage property of the RadMaskedInput control.

Example 4: Setting predefined error message in XAML

<telerik:RadMaskedTextInput ErrorMessage="Invalid email address"/> 

Figure 1: Custom error message

WPF RadMaskedInput Custom error message

Display Validation Errors

The visual element that presents the validation errors is not displayed by default when there is an error. If you want to display it set the ValidationHelper.DisplayValidationErrors attached property on the masked input control to True.

Example 5: Enabling the validation errors visual

<telerik:RadMaskedTextInput maskedInput:ValidationHelper.DisplayValidationErrors="True"  /> 

See Also

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