ViewModel binding via XAML isn't working.

[solatticus]

I'm not able to get a view model bound via XAML. If I set it after the InitializeComponent call in the page constructor, it works though.

Checked in an example: https://github.com/solatticus/Ooui.Samples

XamlParseException: Position 8:10. Type sample:ChatSampleViewModel not found in xmlns Ooui.Samples.Forms
Xamarin.Forms.Xaml.CreateValuesVisitor.Visit(ElementNode node, INode parentNode)
Xamarin.Forms.Xaml.ElementNode.Accept(IXamlNodeVisitor visitor, INode parentNode)
Xamarin.Forms.Xaml.RootNode.Accept(IXamlNodeVisitor visitor, INode parentNode)
Xamarin.Forms.Xaml.XamlLoader.Visit(RootNode rootnode, HydrationContext visitorContext)
Xamarin.Forms.Xaml.XamlLoader.Load(object view, string xaml)
Xamarin.Forms.Xaml.Extensions.LoadFromXaml<TXaml>(TXaml view, Type callingType)
Ooui.Samples.Forms.ChatSamplePage.InitializeComponent() in Ooui.Samples.Forms.ChatSamplePage.xaml.g.cs

        [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Xamarin.Forms.Build.Tasks.XamlG", "0.0.0.0")]
        private global::Xamarin.Forms.ListView MessageListView;

        [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Xamarin.Forms.Build.Tasks.XamlG", "0.0.0.0")]
        private void InitializeComponent() {
            global::Xamarin.Forms.Xaml.Extensions.LoadFromXaml(this, typeof(ChatSamplePage));
            UsersListView = global::Xamarin.Forms.NameScopeExtensions.FindByName<global::Xamarin.Forms.ListView>(this, "UsersListView");
            MessageListView = global::Xamarin.Forms.NameScopeExtensions.FindByName<global::Xamarin.Forms.ListView>(this, "MessageListView");
        }
    }
}
Ooui.Samples.Forms.ChatSamplePage..ctor() in ChatSamplePage.xaml.cs

namespace Ooui.Samples.Forms
{
    public partial class ChatSamplePage : ContentPage
    {
       public ChatSamplePage()
        {
            InitializeComponent();
            //BindingContext = new ChatSampleViewModel();
        }
    }
}
Ooui.AspNetCore.SignalR.Controllers.HomeController.SignalRDemo() in HomeController.cs

        {
            return View();
        }
        public ElementResult SignalRDemo()
        {
            var oe = new ChatSamplePage().GetOouiElement();
            var er = new ElementResult(oe, "SignalR Sample");
            return er;
        }
    }
}

lambda_method(Closure , object , object[] )
Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(object target, object[] parameters)
Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor+SyncActionResultExecutor.Execute(ObjectMethodExecutor executor, object controller, object[] arguments)
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
Microsoft.AspNetCore.Builder.OouiMiddlewareExtensions+<>c__DisplayClass0_0+<<UseOoui>b__0>d.MoveNext()
Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

[praeclarum]

Did you put your ViewModel in a separate DLL? It's possible it hasn't been loaded when Forms goes looking for it.

[solatticus]

It’s all in the same project.

Sent from ProtonMail Mobile

On Fri, Mar 30, 2018 at 4:00 PM, Frank A. Krueger notifications@github.com wrote:

Did you put your ViewModel in a separate DLL? It's possible it hasn't been loaded when Forms goes looking for it.

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or mute the thread.

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[praeclarum]

OK, cool. Can you also paste in some of the XAML where you declare the namespace and create the binding? I've never done the binding in XAML.

[solatticus]

It’s in the link I posted, but I can copy it over when I get home.

Thanks for this!

Sent from ProtonMail Mobile

On Fri, Mar 30, 2018 at 4:05 PM, Frank A. Krueger notifications@github.com wrote:

OK, cool. Can you also paste in some of the XAML where you declare the namespace and create the binding? I've never done the binding in XAML.

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or mute the thread.

{"api_version":"1.0","publisher":{"api_key":"05dde50f1d1a384dd78767c55493e4bb","name":"GitHub"},"entity":{"external_key":"github/praeclarum/Ooui","title":"praeclarum/Ooui","subtitle":"GitHub repository","main_image_url":"https://cloud.githubusercontent.com/assets/143418/17495839/a5054eac-5d88-11e6-95fc-7290892c7bb5.png","avatar_image_url":"https://cloud.githubusercontent.com/assets/143418/15842166/7c72db34-2c0b-11e6-9aed-b52498112777.png","action":{"name":"Open in GitHub","url":"https://github.com/praeclarum/Ooui"}},"updates":{"snippets":[{"icon":"PERSON","message":"@praeclarum in #123: OK, cool. Can you also paste in some of the XAML where you declare the namespace and create the binding? I've never done the binding in XAML."}],"action":{"name":"View Issue","url":"https://github.com/praeclarum/Ooui/issues/123#issuecomment-377610572"}}}

[praeclarum]

Sorry, missed the link, it's perfect.

[zbigniew-gajewski]

In my case (WASM + Xamarin Forms) MVVM works as expected (Button.Command, Button.Text). Example here: https://github.com/zbigniew-gajewski/ooui-wasm-aspnet-core-xaml

[solatticus]

Does declaring & binding the ViewModel via XAML work?

[zbigniew-gajewski]

Yes! (at least Button.Command, Button.Text). Here is working example (based on Ooui.Wasm) with declarative binding XAML / ViewModel: https://github.com/zbigniew-gajewski/ooui-wasm-aspnet-core-xaml

[MarkStega]

I have also had success binding to the viewmodel directly from XAML:

<?xml version="1.0" encoding="utf-8" ?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:infrastructureMVVMFrameworkConverters="clr-namespace:OouiWXF.Infrastructure.MVVMFramework.Converters" xmlns:local="clr-namespace:OouiWXF" xmlns:viewModel="clr-namespace:OouiWXF.ViewModels.MainPage" x:Class="OouiWXF.MainPage">

`

</ContentPage.BindingContext>`

<Label x:Name="StartNarrative" Text="{Binding pStartNarrative, Mode=TwoWay}" />

and then in MainPage.cs class definition:

static public MainPageViewModel pMainPageViewModel;

and in the constructor:

pMainPageViewModel = (MainPageViewModel)this.BindingContext;

[MarkStega]

Here is a repository with the complete code: https://bitbucket.org/MarkStegaOHI/oouiwxf/src/develop/

Thanks to @zbigniew-gajewski for the dll & wasm types in the web server project; I've been meaning to get to this for a while.