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xamarin / XamarinCommunityToolkit

The Xamarin Community Toolkit is a collection of Animations, Behaviors, Converters, and Effects for mobile development with Xamarin.Forms. It simplifies and demonstrates common developer tasks building iOS, Android, and UWP apps with Xamarin.Forms.
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[Bug] NumericValidationBehavior throws an exception #1988

Open mmiller-d8 opened 1 year ago

mmiller-d8 commented 1 year ago

Description

I had this in the wrong area, so I'm moving it here. #1984 Although, I'm starting to wonder if anyone is actually triaging these.

Edit: Apparently, I can't add a label for the area.

Anyways...

In the Maui Community Tookit, the NumericValidationBehavior throws an exception if the entry field is empty.

Looking at the source, the first line in ValidateAsync throws an ArgumentNullException if the value is null. Unless I’m missing something, there’s no way to catch that and it crashes the app.

It should just return false. Ideally, there would be an IsRequired property that would allow it to return true if the value was null or empty.

Steps to Reproduce

  1. Create a page with an entry field.
  2. Add a NumericValidationBehavior and set the validation behavior to on lose focus
  3. Tap the entry field and then tap something else to take way it's focus
  4. Boom. It crashes the app

Expected Behavior

You can leave a field empty without crashing the app

Actual Behavior

It crashes the app

Basic Information

Workaround

No. I downloaded the source and created a local version with the change.

bijington commented 1 year ago

You actually want this repo: https://github.com/CommunityToolkit/Maui

That being said our documentation explains how to avoid this:

https://learn.microsoft.com/dotnet/communitytoolkit/maui/get-started?tabs=CommunityToolkitMaui#using-the-nuget-packages

mmiller-d8 commented 1 year ago

Thanks.

So, I have to turn off all exceptions in all behaviors to avoid one issue? My opinion still stands that it is a poor design choice and should be changed.

bijington commented 1 year ago

That is currently the case yes. I would add that the exceptions being thrown typically only relate to whether you want to safely handle nulls as a default value.

Feel free to open a discussion on the repository if you feel you have something to propose as a change