How to set XamlRoot for ContentDialog when using C# Markup + MVUX

[liziyu0714]

I want to open a ContentDialog through my Model,as the document said,I need to set the Xamlroot.
But I am using the C# Markup + MVUX and don't know how to access the Page .
What should I do?

[morning4coffe-dev]

Hey @liziyu0714,

Thanks for your question! I recommend creating a custom service that you initialize with a XamlRoot (e.g., from App.cs during startup). Once the app loads, this service can provide the value whenever you call it. For more details on opening a ContentDialog from a ViewModel, check out this guide: https://platform.uno/docs/articles/features/dialogs.html?tabs=mvux%2Ccs-markup#opening-a-contentdialog-from-a-modelviewmodel
Let me know if this helps.

[DevTKSS]

@morning4coffe-dev don't know if without linking its not notification you or you dont like to answer... could understand that if its simple for a pro.
So you told, to "simply" add a void below which do the initialization of the class you provided in zip.
Tryed to do what you said in the last snipped and stumbling over a question, you might could answer?
Maybe I missunderstood also the mvux thing in connection to the Model (not ViewModel which is generated in c# markup):
In the template Sub "GoToSecond" is called via a simple "() => GoToSecond" which task is placed in the model and uses the navigator extension. Your example is using the MainPage, not MainModel like this. The xaml ui examples are also using the (Object sender, RoutedEventArgs e) which made me think, this seems to not made for c# markup with mvux. Is that thought right, or would you, as more experienced Developer, tell that this is wrong understood? Is a mvux c# app still using this eventbased thing?
I am referring for this to uno documentation Reference/UI/Features/Dialogs:
"MVUX
If you are using the MVUX pattern, you don't need to specify the Command. Instead, you can directly call the dialog display method in your view, it is generated automatically in BindableModel:

C#

public async Task DisplayDeleteFileDialogCommand()
{
// ...
}"
assuming from this, I thought I will have to use a task in the vm.SomeContentDialog to correctly do that, but if I do so, I see no chance to get on the xamlRoot. For me it seems like a deadlock (maybe just in my head) how to get the xaml root available outside of the page itself. In the previous mentioned Dialog reference is also mentioned to use this RootProvider thing, but "At App initialization",
so I went to the app.xaml.cs file in my application and stumbled over the configureServices where I could addSingleton. But seems like its not satisfied with that and this seems to do no new method on the way, but needs a interface, so the service has to be instance able...
" .ConfigureServices((context, services) =>
{
// TODO: Register your services
//services.AddSingleton<IMyService, MyService>();
})"
but this would need a Interface, which is not possible while using the void and propertys as static.
Could you give me your Opinion to that? The idea would be, to init it once, but... where? on the MainPage? fine with me, but then we will be stuck again with the fact, that its not application wide, just in mainPage. Its like a dog biting its own tail.

[liziyu0714]

@DevTKSS

Is a mvux c# app still using this eventbased thing?

You can refer to the document: Commands.
In mvux ,the viewmodel is auto generated from the model, and your methods are packed up automatically to commands so that you can use something like "() => GoToSecond", it has nothing to do with event.

For me it seems like a deadlock (maybe just in my head) how to get the xaml root available outside of the page itself.

In mvux , you can still use events, and use them in the Page Class (eg. MainPage.cs).
That is to say , you can call Initialize in the Loaded event of the Page:

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.DataContext<MainViewModel>((page, vm) => page
            .NavigationCacheMode(NavigationCacheMode.Required)
            .Background(Theme.Brushes.Background.Default)
            .Content(...);
        this.Loaded += (sender, args) => { XamlRootService.Initialize(XamlRoot); };
    }
}

If you still have any questions , please ask me.

[DevTKSS]

@liziyu0714
thanks for reply.
So you got it working?
I am still struggeling to get the dialog shown sadly. Along documentation it should be possible to call this from Model after filling the xamlRoot to that service he gave in the zip file and filling the xamlroot in the loaded event. But (if you maybe seen my opened Question topic) on my end there is nothing showing up and instead the syncronizationContext seems to be suddenly null after going to the model to run the task instead of doing it in the Main Page. Does this happen on your side also using that service? It dont make any sense to me or the others (discussing also on discord) why that do happen.

[morning4coffe-dev]

Hey @DevTKSS, sorry for the delay in my response, did you manage to get it working with C#M+MVUX? I can take a look into creating a sample for this as well, if you need one, but similar concepts should apply.

[DevTKSS]

sadly no, but changed to xaml markup and the call of the dialog from the xaml.cs codebehind which worked. Like @liziyu0714 said in the comments below, it happend on her side also and I checked with @mikernet via discord also before opening a seperate issue to that. Would appreciate if someone has a working solution to that issue to be able in the future to call a contentdialog from viewmodel again in the future. Issue number to that with full description and provided repo: #18657
Feel free to also take a look into that. Used the service you provided which is at least working, but got some UI thread problems which makes it not possible for me to get it working from MainModel which should be possible if we look in the documentation which tells its possible from ViewModel with such a service. Seems like there is a problem in the generated code for me, but I am clearly no professional on this.

[liziyu0714]

Thanks!
Could you provide an example?
I don't know how to implement the service.

[morning4coffe-dev]

Here’s a simple sample I created that you can download and review: XamlRootSample.zip. It uses a basic architecture, making it applicable for both MVVM and MVUX since it relies on static services for simplicity, which is suitable for this case. For your project, you can take the ShowDialogAsync method from MainPage and move it to your Model/ViewModel—just remember to call XamlRootService.Initialize at some point during app startup (you can use the same Loaded method with C#M).

[liziyu0714]

Yes.I write an similar service to get xamlroot, and it works in MVVM template. But in my project using mvux it doesn't work, just like yours. And I find that if you call showasync in loaded method(in mvux),it can work.

…

________________________________ From: DevTKSS ***@***.***> Sent: Saturday, November 2, 2024 12:46:56 AM To: unoplatform/uno ***@***.***> Cc: liziyu0714 ***@***.***>; Mention ***@***.***> Subject: Re: [unoplatform/uno] How to set XamlRoot for ContentDialog when using C# Markup + MVUX (Discussion #18598) @liziyu0714<https://github.com/liziyu0714> thanks for reply. So you got it working? I am still struggeling to get the dialog shown sadly. Along documentation it should be possible to call this from Model after filling the xamlRoot to that service he gave in the zip file and filling the xamlroot in the loaded event. But (if you maybe seen my opened Question topic) on my end there is nothing showing up and instead the syncronizationContext seems to be suddenly null after going to the model to run the task instead of doing it in the Main Page. Does this happen on your side also using that service? It dont make any sense to me or the others (discussing also on discord) why that do happen. — Reply to this email directly, view it on GitHub<#18598 (reply in thread)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AM4YCZDXS5SN5NFJOY4IRK3Z6OWABAVCNFSM6AAAAABQUWVRPWVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTCMJSGQYTOMA>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[DevTKSS]

but... just a thought: If i can only call it from the loaded event method, I can not trigger it from a button command, so would that make any sense? Possibly I just misunderstood it

[liziyu0714]

in mvvm template ,it can be called from model.But in mvux,it can't

…

________________________________ From: DevTKSS ***@***.***> Sent: Saturday, November 2, 2024 12:58:43 AM To: unoplatform/uno ***@***.***> Cc: liziyu0714 ***@***.***>; Mention ***@***.***> Subject: Re: [unoplatform/uno] How to set XamlRoot for ContentDialog when using C# Markup + MVUX (Discussion #18598) but... just a thought: If i can only call it from the loaded event method, I can not trigger it from a button command, so would that make any sense? Possibly I just misunderstood it — Reply to this email directly, view it on GitHub<#18598 (reply in thread)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AM4YCZBOVYGUIDEZCKGY2ILZ6OXMHAVCNFSM6AAAAABQUWVRPWVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTCMJSGQZTAMY>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[DevTKSS]

added that point as link to my question topic post, to be maybe an issue. Dont know if they can escalate it to one but I think its relevant that it only happens in mvux
I did try on xaml.cs along the video and suddenly a ContentDialog appeared. But in my opinion its not meant to be that way if in the documentation they telling its able to call it from the model also