IState<T> update property inside object doesn`t work

[limeniye]

I have AuthorizationCredentials type:

public enum AutorizationMode
{
    SignIn,
    SignUp
}

public record AuthorizationCredentials
{
    public AutorizationMode AutorizationMode { get; init; }

    public string? UserName { get; init; }

    public string? Password { get; init; }

    public string? RepeatedPassword { get; init; }
}

I`m try to notify my view that AutorizationMode property was changed.

public IState<AuthorizationCredentials> Credentials => State<AuthorizationCredentials>.Empty(this);

public async ValueTask SomeTestMethod(CancellationToken ct)
{
    await Credentials.UpdateValue(opt => opt.Map(credintials => credintials with { AutorizationMode = AutorizationMode.SignUp}), ct);
}

<PasswordBox x:Name="repeatePassowrdTextBox">
    <i:Interaction.Behaviors>
        <core:DataTriggerBehavior Binding="{Binding Credentials.AutorizationMode, Mode=OneWay, Converter={StaticResource EnumToIntConverter}}" Value="0">
            <core:ChangePropertyAction TargetObject="{Binding ElementName=repeatePassowrdTextBox}" PropertyName="Visibility" Value="Collapsed"/>
        </core:DataTriggerBehavior>
    </i:Interaction.Behaviors>
</PasswordBox>

But the breakpoint in mine EnumToIntConverter doesn't work after UpdateValue.
Am I doing something wrong?

[francoistanguay]

Are your bindings working (besides the changes not working?) ?
That state object must be contained in a class (typically a Model), for which the Reactive Source Generator is generating a "Bindable" version of it and this is what should be set in the DataContext of your View.

Are you able to share a repro? A bit more details about the surrounding code? Whether or not it's using Uno Navigation?

Thanks!

[limeniye]

@francoistanguay, yes, I'm using Uno navigation.

Passowrd and Login binding works well because I don't use some converters and don't change values from ViewMode code.

• App.xaml.hosts
• AuthorizationViewModel
• AuthorizationPage
• EnumToIntConverter

[dr1rrb]

Hey @limeniye,

I think your issue is because you have created an Empty state : State<AuthorizationCredentials>.Empty(this);. Empty means that you are creating a state which does not have any value, i.e. Option.None<AuthorizationCredentials>() (if you used a FeedView to render it, you have been in the empty visual state).

Then when you try to update it, you are using Option.Map() which is a helper that will apply the projection only if the given option do have a value (i.e. Option.Some), and will keep the previous option's type otherwise. So in your case you are staying in the Option.None.

To fix it you have 2 options (applying only one will make it works, but I would recommend that you do both to better reflect what you try to achieve):

Create non empty state

public IState<AuthorizationCredentials> Credentials => State.Value(this, () => new AuthorizationCredentials());

Force the update to set the desired value, no matter current state

public async ValueTask SetAuthorizationMode(string mode, CancellationToken ct)
{
	AutorizationMode modeEnum = (AutorizationMode)Enum.Parse(typeof(AutorizationMode), mode);

	await Credentials.Update(creds => (creds ?? new()) with { AutorizationMode = modeEnum }), ct);
}

Note: This is using the Update() that will directly unwrap the Option for you (providing a creds = default(AuthorizationCredentials) if option is not Some). You prefer to work with options and UpdateValue, you can do : await Credentials.UpdateValue(opt => (opt.SomeOrDefault() ?? new()) with { AutorizationMode = modeEnum }), ct);

[limeniye]

@dr1rrb, thank you for your answer.
Yes, it works for me.
I am very grateful to you.

[limeniye]

@dr1rrb , Yes, it works for me in this case.
But, it works only if all properties inside one type.
For example:

public partial class MainViewModel
{
    public IState<SomePropery123> A => State.Value(this, () => new SomePropery123());
    public IState<SomePropery123222> B => State.Value(this, () => new SomePropery123222());
    public IState<SomePropery12311111> C => State.Value(this, () => new SomePropery123111());
    public IState<SomePropery44> D => State.Value(this, () => new SomePropery44());
    // Some command
}

If I want to split this class into separate entities I have an issue:

public partial class MainViewModel
{
    public IState<SomeClassA> SomeObjectOne => State.Value(this, () => new SomeClassA());
    public IState<SomeClassB> SomeObjectTwo => State.Value(this, () => new SomeClassB());
}

public record SomeClassA
{
    public IState<SomePropery123> A => State.Value(this, () => new SomePropery123());
    public IState<SomePropery123222> B => State.Value(this, () => new SomePropery123222());    

    // Some command
}

public record SomeClassB
{
    public IState<SomePropery12311111> C => State.Value(this, () => new SomePropery123111());
    public IState<SomePropery44> D => State.Value(this, () => new SomePropery44());
}

In view side I changed binding from ="{Binding A.Name}" to ="{Binding SomeObjectOne.A.Name}".

The issue:

Error: BindingExpression path error: 'Name' property not found on 'Uno.Extensions.Reactive.Core.StateImpl`1[Ligric.UI.ViewModels.Presentation.ApiDataViewModel]'. BindingExpression: Path='AddingApi.Name' DataItem='Ligric.UI.ViewModels.Presentation.BindableUserApiViewModel'; target element is 'Microsoft.UI.Xaml.Controls.TextBox' (Name='null'); target property is 'Text' (type 'String')

The important thing is that this error only appears for IState properties, but not for commands. All commands work correctly.

[dr1rrb]

We generate the "bindable friendly proxy" only for classes suffixed by "Model" (configurable in your assembly). So here for the binding path SomeObjectOne.A the returned object is an IState (not an instance of SomePropery123), which does not have any property named Name.

But even if you suffix your class by "Model" (and use the generated type BindableSomeClassAModel), it will not work properly: entities that are going through feeds are expected to be immutable, which is not the case of SomeClassA (as it holds a state which is by nature mutable). If you do something like that, any update on IState<SomeClassA> SomeObjectOne will create a new instance of SomeClassA driving to possible loose of information.

I would recommend that you keep the IState only at the root level of your models (e.g SomeClassB / SomeObjectTwo) and re-use the entity itself. But if you really want to re-use a sub model between pages (for commands for instance), you should be able to instance the generated proxy directly (be aware that is not yet a officially supported use-case, you might face some weird issues), e.g. SomeClassAModel / SomeObjectOne:

public partial class MainViewModel
{
    public BindableSomeClassAModel SomeObjectOne { get; } = new();
    public IState<SomeClassB> SomeObjectTwo => State.Value(this, () => new SomeClassB());
}

public record SomeClassAModel
{
    public IState<SomePropery123> A => State.Value(this, () => new SomePropery123());
    public IState<SomePropery123222> B => State.Value(this, () => new SomePropery123222());    

    // Some command
}

public record SomeClassB
{
    public SomePropery12311111 C  { get; init; } = new();
    public SomePropery44 D  { get; init; } = new();
}