`ObservableProperty` seems to break JSON Deserialization when used with `JsonSerializerContext`

[karmeye]

Describe the bug

Using this, the property is not populated with the json value.

[ObservableProperty]
[property: JsonPropertyName("from_uuid")]
[property: JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
private string? fromUuid;

However, if I write it manually it works.

[JsonPropertyName("from_uuid")]
[JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
public string? FromUuid
{
    get => fromUuid;
    set
    {
        if (!EqualityComparer<string?>.Default.Equals(fromUuid, value))
        {
            fromUuid = value;
            OnPropertyChanged(nameof(FromUuid));
        }
    }
}
private string? fromUuid;

Regression

No response

Steps to reproduce

See description above. Use source-generation based serialization rather than reflection.

Expected behavior

I would expect it to deserialize. Not sure if it's Mvvm issue or System.Text.Json. But reported it here.

Screenshots

No response

IDE and version

VS 2022

IDE version

No response

Nuget packages

• CommunityToolkit.Common
• CommunityToolkit.Diagnostics
• CommunityToolkit.HighPerformance
• CommunityToolkit.Mvvm (aka MVVM Toolkit)

Nuget package version(s)

8.2.2

Additional context

Probably serialization also doesn't work.

Help us help you

No, just wanted to report this

[puli1027]

I also encountered this problem

[stephenquan]

I also encountered this issue with the following sample class:

public partial class Person : ObservableObject
{
    [ObservableProperty]
    [property: JsonPropertyName("f")]
    [NotifyPropertyChangedFor(nameof(FullName))]
    string firstName = string.Empty;

    [ObservableProperty]
    [property: JsonPropertyName("n")]
    [NotifyPropertyChangedFor(nameof(FullName))]
    string lastName = string.Empty;

    public string FullName => $"{FirstName} {LastName}";
}

With the application encountering an exception on startup. This appears to be a regression in CommunityToolkit.Mvvm 8.3.0 whereas it is working in 8.2.2.

I created a standalone repo https://github.com/stephenquan/Maui.Mvvm.Json.Test that demonstrates this.

[Sergio0694]

@stephenquan are you able to provide a minimal repro, possibly like a unit test or some self-contained code snippet that replicates the issue? Are you seeing differences in the generated code between 8.2.2 and 8.3.0 in your case? Thank you!

[stephenquan]

@Sergio0694 see my comment where I provided a github repo that is a minimal repro. I checked in the 8.2.2 generated file for Person.cs https://github.com/stephenquan/Maui.Mvvm.Json.Test/blob/main/GeneratedFiles/Maui.Mvvm.Json.Test.Person.g.cs.txt and the 8.3.0 generated file is in the mvvm-8.3.0 branch https://github.com/stephenquan/Maui.Mvvm.Json.Test/blob/mvvm-8.3.0/GeneratedFiles/Maui.Mvvm.Json.Test.Person.g.cs.txt

You can see the changes between 8.2.2 to 8.3.0 included the GeneratedFiles thru this commit reference: stephenquan/Maui.Mvvm.Json.Test@a8f06ce

[Sergio0694]

Yeah I saw that, that's why I asked for a minimal repro, as in, a self-contained snippet. If you actually meant that that is a minimal repro, as in, removing MAUI doesn't reproduce the issue anymore, then I suspect this might be unrelated from the MVVM Toolkit itself. I don't even have the MAUI workload installed, that's also why I'm asking for a standalone minimal repro 🙂

[Sergio0694]

The generated code is identical (except for INotifyPropertyChanging events, I assume you disabled that?) 🤔

[stephenquan]

I don't know why the changing events look different. It definitely wasn't intentional.

[stephenquan]

The exceptions in my app are .NET MAUI errors. Below is the exception/stacktrace when the app is in it's startup sequence. I will try creating another app, say, a console app.

at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean wrapExceptions)
at Microsoft.Maui.Controls.ShellContent.<>c__DisplayClass19_0.<Microsoft.Maui.Controls.IShellContentController.GetOrCreateContent>b__0()
at Microsoft.Maui.Controls.ElementTemplate.CreateContent()
at Microsoft.Maui.Controls.Internals.DataTemplateExtensions.CreateContent(DataTemplate self, Object item, BindableObject container)
at Microsoft.Maui.Controls.ShellContent.Microsoft.Maui.Controls.IShellContentController.GetOrCreateContent()
at Microsoft.Maui.Controls.Handlers.ShellContentHandler.CreatePlatformElement()
at Microsoft.Maui.Handlers.ElementHandler2.OnCreatePlatformElement() at Microsoft.Maui.Handlers.ElementHandler.CreatePlatformElement() at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context) at Microsoft.Maui.Controls.Handlers.ShellSectionHandler.SyncNavigationStack(Boolean animated, NavigationRequestedEventArgs e) at Microsoft.Maui.Controls.Handlers.ShellSectionHandler.MapCurrentItem(ShellSectionHandler handler, ShellSection item) at Microsoft.Maui.PropertyMapper2.<>c__DisplayClass5_0.b__0(IElementHandler h, IElement v)
at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView)
at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView)
at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view)
at Microsoft.Maui.Controls.Handlers.ShellSectionHandler.SetVirtualView(IElement view)
at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler)
at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value)
at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context)
at Microsoft.Maui.Controls.Handlers.ShellItemHandler.UpdateCurrentItem()
at Microsoft.Maui.Controls.Handlers.ShellItemHandler.MapCurrentItem(ShellItemHandler handler, ShellItem item)
at Microsoft.Maui.PropertyMapper2.<>c__DisplayClass5_0.<Add>b__0(IElementHandler h, IElement v) at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView) at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView) at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view) at Microsoft.Maui.Controls.Handlers.ShellItemHandler.SetVirtualView(IElement view) at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler) at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value) at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context) at Microsoft.Maui.Controls.Platform.ShellView.CreateShellItemView() at Microsoft.Maui.Controls.Platform.ShellView.SwitchShellItem(ShellItem newItem, Boolean animate) at Microsoft.Maui.Controls.Handlers.ShellHandler.MapCurrentItem(ShellHandler handler, Shell view) at Microsoft.Maui.PropertyMapper2.<>c__DisplayClass5_0.b__0(IElementHandler h, IElement v)
at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView)
at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView)
at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view)
at Microsoft.Maui.Handlers.ViewHandler2.SetVirtualView(IView view) at Microsoft.Maui.Controls.Handlers.ShellHandler.SetVirtualView(IView view) at Microsoft.Maui.Handlers.ViewHandler2.SetVirtualView(IElement view)
at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler)
at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value)
at Microsoft.Maui.Controls.VisualElement.Microsoft.Maui.IElement.set_Handler(IElementHandler value)
at Microsoft.Maui.Platform.ElementExtensions.ToHandler(IElement view, IMauiContext context)
at Microsoft.Maui.Platform.ElementExtensions.ToPlatform(IElement view, IMauiContext context)
at Microsoft.Maui.Handlers.WindowHandler.MapContent(IWindowHandler handler, IWindow window)
at Microsoft.Maui.PropertyMapper`2.<>c__DisplayClass5_0.b__0(IElementHandler h, IElement v)
at Microsoft.Maui.PropertyMapper.UpdatePropertyCore(String key, IElementHandler viewHandler, IElement virtualView)
at Microsoft.Maui.PropertyMapper.UpdateProperties(IElementHandler viewHandler, IElement virtualView)
at Microsoft.Maui.Handlers.ElementHandler.SetVirtualView(IElement view)
at Microsoft.Maui.Controls.Element.SetHandler(IElementHandler newHandler)
at Microsoft.Maui.Controls.Element.set_Handler(IElementHandler value)
at Microsoft.Maui.Platform.ElementExtensions.SetHandler(IWinRTObject nativeElement, IElement element, IMauiContext context)
at Microsoft.Maui.Platform.ElementExtensions.SetWindowHandler(Window platformWindow, IWindow window, IMauiContext context)
at Microsoft.Maui.Platform.ApplicationExtensions.CreatePlatformWindow(Application platformApplication, IApplication application, OpenWindowRequest args)
at Microsoft.Maui.Platform.ApplicationExtensions.CreatePlatformWindow(Application platformApplication, IApplication application, LaunchActivatedEventArgs args)
at Microsoft.Maui.MauiWinUIApplication.OnLaunched(LaunchActivatedEventArgs args)
at Microsoft.UI.Xaml.Application.Microsoft.UI.Xaml.IApplicationOverrides.OnLaunched(LaunchActivatedEventArgs args)
at ABI.Microsoft.UI.Xaml.IApplicationOverrides.Do_Abi_OnLaunched_0(IntPtr thisPtr, IntPtr args)

[Sergio0694]

"I don't know why the changing events look different. It definitely wasn't intentional."

Oh I see, that's due to #722. By the way, in 8.3.0, you use:

<PropertyGroup>
  <MvvmToolkitEnableINotifyPropertyChangingSupport>false</MvvmToolkitEnableINotifyPropertyChangingSupport>
</PropertyGroup>

If you want to disable support for INotifyPropertyChanging entirely, if you don't need it.

[stephenquan]

@Sergio0694 I tried the Person class in a straight console top-level application and it works with CommunityToolkit.Maui 8.3.0 with no issue. Would you like me to split my issue into a new one that is "MAUI + CommunityToolkit.Mvvm 8.3.0 + Json" ? Also, because it's MAUI, I'm unsure if my issue belongs in this repo anymore or over in https://github.com/dotnet/maui ?

using CommunityToolkit.Mvvm.ComponentModel;
using System.Text.Json.Serialization;
using System.Text.Json;
string json = @"{""f"":""John"",""n"":""Doe""}";
var person = JsonSerializer.Deserialize<Person>(json);
Console.WriteLine(person.FullName); // Output: John Doe
public partial class Person : ObservableObject
{
    [ObservableProperty]
    [property: JsonPropertyName("f")]
    [NotifyPropertyChangedFor(nameof(FullName))]
    string firstName = string.Empty;
    [ObservableProperty]
    [property: JsonPropertyName("n")]
    [NotifyPropertyChangedFor(nameof(FullName))]
    string lastName = string.Empty;
    public string FullName => $"{FirstName} {LastName}";
}

[Sergio0694]

@stephenquan could you try #923 (comment) in your MAUI app with 8.3.0 and see if that fixes the crash? I wonder if it's the same issue.

[stephenquan]

Hi @Sergio0694, thanks for the suggestion, so, I tried adding a WindowsSdkPackageVersion to match the TargetFrameworks .NET MAUI sets, and this is what it looks like:

<TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows'))">$(TargetFrameworks);net8.0-windows10.0.19041.0</TargetFrameworks>
<WindowsSdkPackageVersion Condition="$([MSBuild]::IsOSPlatform('windows'))">10.0.19041.0</WindowsSdkPackageVersion>

But it resulted in the following error:

1>F:\Maui\Maui.Mvvm.Json.Test\Maui.Mvvm.Json.Test\Maui.Mvvm.Json.Test.csproj : error NU1102: Unable to find package Microsoft.Windows.SDK.NET.Ref with version (= 10.0.19041)
1>F:\Maui\Maui.Mvvm.Json.Test\Maui.Mvvm.Json.Test\Maui.Mvvm.Json.Test.csproj : error NU1102: - Found 263 version(s) in NuGet [ Nearest version: 10.0.19041.1-preview ]

So I bumped the WindowsSdkPackageVersion up

<WindowsSdkPackageVersion Condition="$([MSBuild]::IsOSPlatform('windows'))">10.0.19041.1-preview</WindowsSdkPackageVersion>

But this generates a new issue:

1>C:\Program Files\dotnet\sdk\8.0.303\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Windows.targets(55,5): error NETSDK1148: A referenced assembly was compiled using a newer version of Microsoft.Windows.SDK.NET.dll. Please update to a newer .NET SDK in order to reference this assembly.

Incidentally, I decided to target my .NET MAUI project for Android, and, surprisingly, the application was built and ran with no issue! So the problem seems to be windows only.