Android/WASM ： prismMvvm：ViewModelLocator.AutoWireViewModel= "True" 不是 Wire-up the ViewModel for And

Question

我正在尝试在视图中使用prismMvvm：ViewModelLocator.AutoWireViewModel="True"自动连接ViewModel。对于UWp来说，它运行得很好。但在Android和WASM中，View无法使用Prism连接我的Uno平台应用程序中的ViewModel。

<UserControl
x:Class="RepayablClient.Shared.Views.Login"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:prismMvvm="using:Prism.Mvvm"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
prismMvvm:ViewModelLocator.AutoWireViewModel="True"
mc:Ignorable="d">
<Grid Background="#881798">
<Grid.RowDefinitions>
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Grid
Width="250"
Height="300"
HorizontalAlignment="Center"
VerticalAlignment="Center">
<Grid.RowDefinitions>
<RowDefinition Height="*" />
<RowDefinition Height="25" />
<RowDefinition Height="25" />
</Grid.RowDefinitions>
<Image
Grid.Row="0"
Source="/Assets/Icon.png"
Stretch="Fill" />
<TextBlock Grid.Row="1" Text="{Binding LoginUser}" />
<ProgressBar
Grid.Row="2"
Width="250"
Margin="0,20,0,0"
Foreground="White"
IsIndeterminate="True"
ShowError="False"
ShowPaused="False" />
</Grid>
</Grid>
</UserControl>

using Microsoft.Identity.Client;
using RepayablClient.ViewModels;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace RepayablClient.Shared.ViewModels
{
public class LoginViewModel : ViewModelBase
{
//public ICommand LoginCommand { get; set; }
string graphAPIEndpoint = "https://graph.microsoft.com/v1.0/me";
private string _loginUser;
public string LoginUser
{
get { return _loginUser; }
set
{
_loginUser = value;
RaisePropertyChanged();
}
}
public LoginViewModel()
{
Title = "Login Page";
LoginUser = "Attempt to Login";
_ = LoginCommandExecutedAsync();
//LoginCommand = new AsyncCommand(LoginCommandExecutedAsync);
}
private async Task LoginCommandExecutedAsync()
{
AuthenticationResult authResult = null;
IEnumerable<IAccount> accounts = await App.publicClientApplication.GetAccountsAsync().ConfigureAwait(false);
IAccount firstAccount = accounts.FirstOrDefault();
try
{
authResult = await App.publicClientApplication.AcquireTokenSilent(Consts.Scopes, firstAccount)
.ExecuteAsync();
}
catch (MsalUiRequiredException ex)
{
System.Diagnostics.Debug.WriteLine($"MsalUiRequiredException: {ex.Message}");
try
{
authResult = await App.publicClientApplication.AcquireTokenInteractive(Consts.Scopes)
.ExecuteAsync();
}
catch (MsalException msalex)
{
// await DisplayMessageAsync($"Error Acquiring Token:{System.Environment.NewLine}{msalex}");
}
}
catch
{
//  await DisplayMessageAsync($"Error Acquiring Token Silently:{System.Environment.NewLine}{ex}");
return;
}
if (authResult != null)
{
var content = await GetHttpContentWithTokenAsync(graphAPIEndpoint,
authResult.AccessToken).ConfigureAwait(false);
LoginUser = content;
}
}
public async Task<string> GetHttpContentWithTokenAsync(string url, string token)
{
var httpClient = new System.Net.Http.HttpClient();
System.Net.Http.HttpResponseMessage response;
try
{
var request = new System.Net.Http.HttpRequestMessage(System.Net.Http.HttpMethod.Get, url);
// Add the token in Authorization header
request.Headers.Authorization =
new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", token);
response = await httpClient.SendAsync(request);
var content = await response.Content.ReadAsStringAsync();
return content;
}
catch (Exception ex)
{
return ex.ToString();
}
}
}
}

有关更多详细信息，请访问我的回购：https://github.com/avikeid2007/Repayabl

Answer 1

您面临的问题仍然存在于Uno中，很快就会进行调整。基本上，如果使用UserControl，则在创建控件时可能不会考虑其中定义的某些属性。

您可以通过以下两种方式之一解决此问题：

• 将UserControl更改为ContentControl
• 在csproj中添加以下属性：

<UnoSkipUserControlsInVisualTree>false</UnoSkipUserControlsInVisualTree>

这个问题是安卓用户界面线程堆栈空间很短的时候遗留下来的，视觉树中的每一层都很重要。它不再那么关键了。