Can't use App.xaml resources after Dependency Injection .NET MAUI

[luis95gr]

Description

I have an application that uses mvvm pattern with Community Toolkit features. I am trying to use Dependency Injection to use an ApiService with its interface in my viewmodels, but after following the steps described here, I can't access to App.xaml Resources (specifically colors), the intellisense works when I am writing code in XAML, but it doesn´t work after running. It is important to notice that I was using colors from resources correctly before trying to use Dependency Injection and changing the ViewModel - View linking method to the one described here, but I was unable to use ApiService. Here is my code.

Steps to Reproduce

App.xaml.cs (Login page is my first page):

public App(LoginPage page)
{
    InitializeComponent();
    MainPage = page;
}

LoginPage.xaml.cs

public partial class LoginPage : ContentPage
{
  public LoginPage(LoginPageViewModel loginPageViewModel)
  {
    BindingContext = loginPageViewModel;
    InitializeComponent();
  }
}

LoginPageViewModel

public LoginPageViewModel(IApiService apiService)
    {
        _apiService = apiService;
        Opacity = 1f;
        IsEnabled = true;
        IsRunning = false;
    }

LoginPage.xaml

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         x:Class="NewScholarApp.Views.LoginPage"
         Title="LoginPage"
         xmlns:vm="clr-namespace:NewScholarApp.ViewModels"
         x:DataType="vm:LoginPageViewModel"
         BackgroundColor="{StaticResource GreenSchool}">

RegisterViews and ViewModels

public static MauiAppBuilder ConfigureViews(this MauiAppBuilder mauiAppBuilder)
    {
        mauiAppBuilder.Services.AddTransient<LoginPage>();

        return mauiAppBuilder;
    }

public static class RegisterViewModels
{

    public static MauiAppBuilder ConfigureViewModels(this MauiAppBuilder mauiAppBuilder)

    {
        mauiAppBuilder.Services.AddSingleton<LoginPageViewModel>();

        return mauiAppBuilder;
    }
}

Link to public reproduction project repository

https://github.com/luis95gr/SampleProject

Version with bug

7.0 (current)

Last version that worked well

Unknown/Other

Affected platforms

Android, I was not able test on other platforms

Affected platform versions

Android 12.1

Did you find any workaround?

Don't use any StaticResource

Relevant log output

Microsoft.Maui.Controls.Xaml.XamlParseException: 'Position 8:14. StaticResource not found for key GreenSchool'

[TWTIC]

Try to change the order like this:

public partial class LoginPage : ContentPage
{
  public LoginPage(LoginPageViewModel loginPageViewModel)
  { 
    InitializeComponent();
    BindingContext = loginPageViewModel;
  }
}

[luis95gr]

Try to change the order like this:

public partial class LoginPage : ContentPage { public LoginPage(LoginPageViewModel loginPageViewModel) { InitializeComponent(); BindingContext = loginPageViewModel; } }

Thank you for the response, but the error still happens even with that change.

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[symbiogenesis]

I encountered this same issue when upgrading to MAUI and switching to the new DI style. This is a bug.

The options for workarounds I found are the following:

1. Best: Inject IServiceProvider and use that to resolve the page only at the moment it is needed.
2. Worse: For the App's MainPage, inject only the ViewModel, not the page, and new-up the page. (Lose DI for the page)
3. Even Worse: Inject the main page using System.Lazy as described here or here
4. Worst of all: Convert all StaticResources in App.xaml to DynamicResources and incur the cost of doing that.

[Eilon]

@luis95gr - we don't seem to have access to https://github.com/luis95gr/NewScholarApp. Can you ensure the repo is public?

Hi @luis95gr. We have added the "s/needs-repro" label to this issue, which indicates that we require steps and sample code to reproduce the issue before we can take further action. Please try to create a minimal sample project/solution or code samples which reproduce the issue, ideally as a GitHub repo that we can clone. See more details about creating repros here: https://github.com/dotnet/maui/blob/main/.github/repro.md

This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

This issue has been automatically marked as stale because it has been marked as requiring author feedback to reproduce the issue but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment. If it is closed, feel free to comment when you are able to provide the additional information and we will re-investigate.