Bind textbox to float value. Unable to input dot / comma

Question

When I try to input a DOT or a COMMA in a textbox, for example 1.02 or 83,33 the textbox prevents me to input such a value (and the input turns red). The textbox is bound to a float property. Why?

I have bound a textbox to a float Property Power of a class implementing INotifyPropertyChanged.

private float _power;

public float Power
{
    get { return _power; }
    set
    {
        _power = value;
        OnPropertyChanged("Power");
    }
}

In Xaml

<TextBox Name="txtPower" Height="23" TextWrapping="Wrap" Text="{Binding Path=Power, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"></TextBox>

I have no custom validation at all right now.

Also tried decimal but it does not work either. For string everything works fine.

xmedeko · Answer 1 · 2019-03-29T07:16:34.340

32

If you have .NET 4.5 or newer, you may enforce the pre 4.5 behaviour

System.Windows.FrameworkCompatibilityPreferences.KeepTextBoxDisplaySynchronizedWithTextProperty = false;

See Sebastian Lux's blog: With .NET 4.5 it is no longer possible to enter a separator character (comma or dot) with UpdateSourceTrigger = PropertyChanged by default. Microsoft says, this intended.

edited Mar 29 '19 at 07:16

answered Mar 11 '16 at 14:22

xmedeko

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The link is broken, which of course is why you shouldn't provide link-only answers. – A.R. Feb 25 '19 at 23:43
@A.R. This is the full contained answer. Just one line of code. The link is just for credits. – xmedeko Feb 26 '19 at 07:18
1

It just suggests "try this" meaning it may not work. No explanation, no context. just a broken link. If you think the one liner does it all, at least make an edit an remove the broken link. – A.R. Feb 27 '19 at 20:05
1

just a note that this will affect all textboxes. https://social.msdn.microsoft.com/Forums/vstudio/en-US/92ae5178-4a92-4784-b30b-226ecb1eb146/decimal-binding-issue-in-wpf – walterhuang Feb 28 '19 at 19:15

score 30 · Accepted Answer · edited Jan 30 '13 at 09:50

30

Try adding a StringFormat definition to the binding. Like so:

<TextBox Name="txtPower" Height="23" 
    TextWrapping="Wrap" Text="{Binding Path=Power, Mode=TwoWay, 
    UpdateSourceTrigger=PropertyChanged,StringFormat=N2}"></TextBox>

edited Jan 30 '13 at 09:50

Ravi Y

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answered Jan 30 '13 at 09:48

yonigozman

707
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3

I used StringFormat={}{##.##} and this works for me. Not sure whats N2. Thanks! – LukeSolar Jan 30 '13 at 10:56
1

@LukeSolar here is a answer for you https://stackoverflow.com/questions/4506323/difference-between-tostringn2-and-tostring0-00 – huoxudong125 Jan 27 '15 at 01:16
14

While this resolve the issue of entering something like 1.1, it adds multiple issues such as number is always displayed with decimals (i.e 1 is shows as 1.00), using backspace or delete keys in box will not work for some reason. Placing cursor befor dot, then typing .11 results in 1.11.11 – pixel Dec 17 '15 at 04:17
@pixel I experience the same behavior and IHMO this is unuseable. Did you find any solution to this, except changing the `UpdateSourceTrigger` to `LostFocus` ? – LuckyLikey Aug 03 '17 at 15:38
For anyone struggling with the `StringFormat` if you need `UpdateSourceTrigger=PropertyChanged` a possible workaround is to bind to a `string` property and then validating that string inside the setter. You can also logically connect it to a `float`, `double`, or `decimal` property, so both values will syncronize. – LuckyLikey Aug 03 '17 at 15:45
@LuckyLikey Sorry, dont remember any more, was long time ago and I believe someone else looked at the issue – pixel Aug 03 '17 at 16:04
Oddly enough, with added `StringFormat` the textbox initially is empty. When I remove StringFormat it correctly shows its initial value (initial value is round one, "1", no decimal points); – astrowalker Jan 23 '20 at 07:40

score 1 · Answer 3 · answered Jul 06 '17 at 10:51

to fix dot and comma issue in textbox binding to decimal or float

1-  UpdateSourceTrigger = LostFocus 
2-  add string format StringFormat={}{0:#.##} to escape unneeded zeros 


<TextBox Name="txtPower" Height="23" 
         TextWrapping="Wrap" Text="{Binding Path=Power, Mode=TwoWay, 
         UpdateSourceTrigger=LostFocus ,StringFormat={}{0:#.##}}"></TextBox>

Bind textbox to float value. Unable to input dot / comma

3 Answers3

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