Format Percentage

Kevin Marois

I have a nullable decimal TaxRate property on an entity. I want to format/style the textbox to enter a percentage. What I have so far doesn't work. If I start out by entering a decimal point, then it works fine. If I start out by entering a digit, then I cannot enter a decimal.

<Setter Property="Text" Value="{Binding SelectedStatesCountiesCities.TaxRate, StringFormat={}{0:N2}%}" />
<Style.Triggers>
    <Trigger Property="IsKeyboardFocused" Value="True">
        <Setter Property="Text" Value="{Binding SelectedStatesCountiesCities.TaxRate}" />
    </Trigger>
</Style.Triggers>

If it's not broken, fix it until it is. Everything makes sense in someone's mind. Ya can't fix stupid.

Richard Deeming

The UpdateSourceTrigger=PropertyChanged option means that your source property is updated every time you press a key in the TextBox. When you type a . character, one of two things will happen:

The box is currently empty. "." on its own cannot be parsed as a decimal, so the property will not be updated.
The box contains an integer:
- decimal.Parse("42.") returns 42.
- The property is updated to 42, triggering the PropertyChanged event.
- The binding on the box updates to reflect the new property value - the text is set to "42".

Depending on what you are trying to do, there may be ways around this - for example, manually updating the source value when the user presses Enter: c# - Binding to a double with StringFormat on a TextBox - Stack Overflow[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

Kevin Marois

Thanks for the reply. Setting UpdateSourceTrigger to LostFocus dit it BTW, here's an interesting solution: [c# - How do I get a TextBox to only accept numeric input in WPF? - Stack Overflow](https://stackoverflow.com/questions/1268552/how-do-i-get-a-textbox-to-only-accept-numeric-input-in-wpf)

If it's not broken, fix it until it is. Everything makes sense in someone's mind. Ya can't fix stupid.