Restriction or Validation in WPF Currency TextBox

18 Nov 20186 minutes to read

This section explains how to validate or restrict the WPF Currency TextBox control value.

Restrict the value within minimum and maximum value

The Value of the WPF Currency TextBox can be restricted within the maximum and minimum limits. Once the value has reached the maximum or minimum value, the value does not exceed the limit. You can change the maximum and minimum limits by using the MinValue and MaxValue properties. The default validation mode for MinValidation and MaxValidation is OnLostFocus.

You can choose when to validate the maximum and minimum limits while changing the values by using the MinValidation and MaxValidation properties.

• OnKeyPress — When MaxValidation or MinValidation is set to OnKeyPress, the value in the WPF Currency TextBox is validated shortly after each key press. As a result, it is not possible to enter any invalid input and the value will never exceed the configured maximum or minimum limits.

• OnLostFocus - When MaxValidation or MinValidation is set to OnLostFocus, the value in the WPF Currency TextBox is validated when the control loses keyboard focus. The WPF Currency TextBox will accept any value during editing; validation takes place only after focus is lost. If the value is then greater than MaxValue or less than MinValue, it is automatically reset to MaxValue or MinValue, respectively.

• MaxValueOnExceedMaxDigit - When you give input greater than specified maximum limit, MaxValueOnExceedMaxDigit property will decide either it should retain the old value or reset to maximum limit that is specified. For example, if MaxValue is set to 100 and you are trying to input 200. Value will changed to 100 when MaxValueOnExceedMaxDigit is true. When MaxValueOnExceedMaxDigit is false, 20 will be retained and last entered 0 will be ignored.

  MaxValueOnExceedMaxDigit property takes effect only when the MaxValidation is set to OnKeyPress.

• MinValueOnExceedMinDigit - When you give input less than specified minimum limit, MinValueOnExceedMinDigit property will decide either it should retain the old value or reset to minimum limit that is specified. For example, if MinValue is set to 200 and the Value is 205 and you are trying change the value to 20. Value will changed to 200 when MinValueOnExceedMinDigit is true. When MinValueOnExceedMinDigit is false, Old value 205 will be retained.

  MinValueOnExceedMinDigit takes effect only when the MinValidation is set to OnKeyPress.

XAML

<syncfusion:CurrencyTextBox x:Name="currencyTextBox" Width="150" MaxValue="100" MinValue="10"
                          MinValueOnExceedMinDigit="True"
                          MinValidation="OnKeyPress" MaxValidation="OnLostFocus"/>

C#

CurrencyTextBox currencyTextBox = new CurrencyTextBox();
currencyTextBox.Width = 150;
currencyTextBox.Height = 25;
currencyTextBox.MinValue = 10;
currencyTextBox.MaxValue =100;
currencyTextBox.MinValidation = MinValidation.OnKeyPress;
currencyTextBox.MaxValidation = MaxValidation.OnLostFocus;
currencyTextBox.MinValueOnExceedMinDigit = true;

MinValidation is set to OnKeyPress, it cannot let to enter a value less than the MinValue. If try to enter a value less than the MinValue, then the MinValue will set to the Value property because MinValueOnExceedMinDigit is set to true.

MaxValidation is set to OnLostFocus, so the MaxValidation will be performed only in the lost focus.

Restrict Number of Decimal Digits

You can format the decimal digits in the WPF Currency TextBox control using CurrencyDecimalDigits property. You can also restrict the decimal digits of the text within minimum and maximum limit in WPF Currency TextBox control using MinimumCurrencyDecimalDigits and MaximumCurrencyDecimalDigits properties. The default value of MinimumCurrencyDecimalDigits,MaximumCurrencyDecimalDigits and CurrencyDecimalDigits properties is -1.

If the value of MinimumCurrencyDecimalDigits property is greater than the value of MaximumCurrencyDecimalDigits property, the text of WPF Currency TextBox will be updated based on value of MinimumCurrencyDecimalDigits property.

XAML

<syncfusion:CurrencyTextBox Value="125.32545" HorizontalAlignment="Center" VerticalAlignment="Center"
                            MaximumCurrencyDecimalDigits="4"
                            MinimumCurrencyDecimalDigits="1" />

C#

CurrencyTextBox currencyTextBox = new CurrencyTextBox();
currencyTextBox.Value = 125.32545;
currencyTextBox.MaximumCurrencyDecimalDigits = 4;
currencyTextBox.MinimumCurrencyDecimalDigits = 1;

When the value of MinimumCurrencyDecimalDigits, MaximumCurrencyDecimalDigits and CurrencyDecimalDigits properties are specified, CurrencyDecimalDigits property takes high precedence and updates the text of WPF Currency TextBox property.

XAML

<syncfusion:CurrencyTextBox Value="125.32545" HorizontalAlignment="Center" VerticalAlignment="Center"
                            MaximumCurrencyDecimalDigits="4"
                            MinimumCurrencyDecimalDigits="1" 
                            CurrencyDecimalDigits="3"
                            />

C#

CurrencyTextBox currencyTextBox = new CurrencyTextBox();
currencyTextBox.Value = 125.32545;
currencyTextBox.MaximumCurrencyDecimalDigits = 4;
currencyTextBox.MinimumCurrencyDecimalDigits = 1;
currencyTextBox.CurrencyDecimalDigits = 3;

Read-Only Mode

The WPF Currency TextBox does not allow the user to input or edit the value when the IsReadOnly property is set to true. The user can still select text and display the cursor on the WPF Currency TextBox by setting the IsReadOnlyCaretVisible property to true. However, the value can still be changed programmatically in read-only mode.

XAML

<syncfusion:CurrencyTextBox x:Name="currencyTextBox" IsReadOnly="True" Value="10" IsReadOnlyCaretVisible="True"/>

C#

CurrencyTextBox currencyTextBox = new CurrencyTextBox();
currencyTextBox.Value = 10;
currencyTextBox.IsReadOnly = true;
currencyTextBox.IsReadOnlyCaretVisible = true;