Mvvm 在视图模型中登录到xamarin.forms中的master details页时出错？
当我试图从登录页面导航到masterDetailpage时，我得到一个错误提示 “System.Reflection.targetingException” Message=调用目标已引发异常。“ 当用户成功登录时，我尝试了登录功能Mvvm 在视图模型中登录到xamarin.forms中的master details页时出错？,mvvm,xamarin.forms,navigation,master-detail,Mvvm,Xamarin.forms,Navigation,Master Detail,当我试图从登录页面导航到masterDetailpage时，我得到一个错误提示 “System.Reflection.targetingException” Message=调用目标已引发异常。“ 当用户成功登录时，我尝试了登录功能 async void Login() { try { var current = Connectivity.NetworkAccess; if (current == Netwo
async void Login()
{
try
{
var current = Connectivity.NetworkAccess;
if (current == NetworkAccess.Internet)
{
if (IsValidated)
{
await navigationRef.PushPopupAsync(new LoaderPage()).ConfigureAwait(false);
userDetails = await webServicesRepository.UserLogin(Phone, Password, "123113123", "Android").ConfigureAwait(false);
if (userDetails != null && userDetails.status == "200")
{
await navigationRef.PopPopupAsync().ConfigureAwait(false);
MasterDetailPage fpm = new MasterDetailPage
{
Master = new MainMenuPageMaster(),
Detail = new NavigationPage(new HomePage())
};
Application.Current.MainPage = fpm;
//Application.Current.MainPage = new NavigationPage(new MainMenuPage());
//await navigationRef.PushAsync(new MainMenuPage()).ConfigureAwait(false);
}
else
{
await navigationRef.PopPopupAsync().ConfigureAwait(false);
await Application.Current.MainPage.DisplayAlert(Constants.DISPLAY_POPUP_TITLE, Constants.NO_DATA_FOUND, Constants.DISPLAY_POPUP_BUTTON).ConfigureAwait(false);
}
}
else
{
await Application.Current.MainPage.DisplayAlert(Constants.DISPLAY_POPUP_TITLE, "You must fill all areas correctly!", Constants.DISPLAY_POPUP_BUTTON).ConfigureAwait(false);
}
}
else
{
await Application.Current.MainPage.DisplayAlert(Constants.DISPLAY_NETWORK_ERROR_TITLE, Constants.DISPLAY_NETWORK_ERROR_MESSAGE, Constants.DISPLAY_POPUP_BUTTON).ConfigureAwait(false);
}
}
catch(Exception ex)
{
Console.WriteLine(ex.InnerException.Message);
await Application.Current.MainPage.DisplayAlert(Constants.DISPLAY_POPUP_TITLE, Constants.NO_DATA_FOUND, Constants.DISPLAY_POPUP_BUTTON).ConfigureAwait(false);
}
}
<?xml version="1.0" encoding="utf-8" ?>
<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:d="http://xamarin.com/schemas/2014/forms/design"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
x:Class="intSetSet.MainMenuPage"
xmlns:views="clr-namespace:XXXXXX"
NavigationPage.HasNavigationBar="False"
xmlns:ios="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"
ios:Page.UseSafeArea="true">
<MasterDetailPage.Master>
<views:MainMenuPageMaster x:Name="masterPage" Title="Menu" Icon="ListIcon.png" />
</MasterDetailPage.Master>
<MasterDetailPage.Detail>
<NavigationPage>
<x:Arguments>
<views:HomePage />
</x:Arguments>
</NavigationPage>
</MasterDetailPage.Detail>
</MasterDetailPage>
public class MainMenuPageViewModel : INotifyPropertyChanged
{
public ObservableCollection<MainMenuPageModel> MenuItems { get; set; }
public ICommand LogoutCommand { get; }
public MainMenuPageViewModel()
{
try
{
MenuItems = new ObservableCollection<MainMenuPageModel>(new[]
{
new MainMenuPageModel { Id = 0, Title = "Home", Icon="shop.png", TargetType= typeof(HomePage) },
new MainMenuPageModel { Id = 1, Title = "Profile", Icon="shop.png", TargetType= typeof(ProfilePage) },
new MainMenuPageModel { Id = 2, Title = "Referral History", Icon="paper_money.png", TargetType= typeof(ReferralHistoryPage) },
});
}
catch(Exception ex)
{
Console.WriteLine(ex.Message);
}
}
#region INotifyPropertyChanged Implementation
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged([CallerMemberName] string propertyName = "")
{
if (PropertyChanged == null)
return;
PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}
public类MainMenuPageViewModel:INotifyPropertyChanged
{
公共ObservableCollection菜单项{get；set；}
公共ICommand LogoutCommand{get；}
公共MainMenuPageViewModel（）
{
尝试
{
MenuItems=新的ObservableCollection（新[]
{
新的MainMenuPageModel{Id=0，Title=“Home”，Icon=“shop.png”，TargetType=typeof（主页）}，
新的MainMenuPageModel{Id=1，Title=“Profile”，Icon=“shop.png”，TargetType=typeof（ProfilePage）}，
新的MainMenuPageModel{Id=2，Title=“转介历史”，Icon=“paper\u money.png”，TargetType=typeof（ReferralHistoryPage）}，
});
}
捕获（例外情况除外）
{
控制台写入线（例如消息）；
}
}
#区域INotifyPropertyChanged实现
公共事件属性更改事件处理程序属性更改；
void OnPropertyChanged（[CallerMemberName]字符串propertyName=”“）
{
if（PropertyChanged==null）
返回；
调用（这是新的PropertyChangedEventArgs（propertyName））；
}
#端区
}
我想在成功登录时从登录页面导航到主控详细信息页面您需要查看InnerException以了解有关根本问题的更多详细信息is@jason如果您能共享一些引用，那就太好了Exception对象有一个InnerException属性。对于TargetInvocationException，InnerException通常包含有关异常根本原因的更多信息；我明白了：无法在未调用Looper的线程[thread-16,5，main]内创建处理程序。prepare（）10-25 17:32:37.952 I/mono stdout（3397）：无法在未调用Looper的线程[thread-16,5，main]内创建处理程序。prepare（）@jason我已经更新了我的问题，以便您能够清楚地了解这个问题。另外，在登录函数catch块中打印内部异常。
<?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:d="http://xamarin.com/schemas/2014/forms/design"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
x:Class="XXXXX.MainMenuPageMaster"
xmlns:ios="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"
ios:Page.UseSafeArea="true">
<StackLayout>
<ListView x:Name="MenuItemsListView"
SeparatorVisibility="None"
x:FieldModifier="public"
HasUnevenRows="true"
ItemsSource="{Binding MenuItems}">
<ListView.Header>
<StackLayout BackgroundColor="#CEDAEE">
<StackLayout Orientation="Horizontal"
Padding="20">
<Image Margin="10,10,0,0"
Source="setsetlogo.png"
WidthRequest="80"
HeightRequest="80"
HorizontalOptions="Start"></Image>
<Label HorizontalOptions="StartAndExpand"
VerticalTextAlignment="Center"
Text="IntSetSet"
TextColor="White"
FontSize="24" />
</StackLayout>
<BoxView BackgroundColor="Teal"
HorizontalOptions="FillAndExpand"
HeightRequest="1"></BoxView>
</StackLayout>
</ListView.Header>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout HorizontalOptions="FillAndExpand"
BackgroundColor="#CEDAEE">
<StackLayout Padding="10,10"
Orientation="Horizontal">
<Image Source="{Binding Icon}"
WidthRequest="40"
HeightRequest="40"
VerticalOptions="Center"
HorizontalOptions="Start"></Image>
<Label VerticalOptions="Center"
VerticalTextAlignment="Center"
HorizontalTextAlignment="Start"
HorizontalOptions="StartAndExpand"
TextColor="White"
Text="{Binding Title}"
FontSize="Medium" />
</StackLayout>
<BoxView BackgroundColor="Teal"
HorizontalOptions="FillAndExpand"
HeightRequest="1"></BoxView>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.Footer>
<StackLayout BackgroundColor="#CEDAEE" Orientation="Horizontal" HorizontalOptions="FillAndExpand">
<Button Command="{Binding LogoutCommand}" Text="LogOut" BackgroundColor="#CEDAEE" TextColor="Yellow" HorizontalOptions="EndAndExpand">
</Button>
<!--<Button Clicked="LogoutButton_Clicked" Text="LogOut" BackgroundColor="#CEDAEE" TextColor="Yellow" HorizontalOptions="EndAndExpand">
</Button>-->
</StackLayout>
</ListView.Footer>
</ListView>
</StackLayout>
</ContentPage>
public partial class MainMenuPageMaster : ContentPage
{
public MainMenuPageMaster()
{
InitializeComponent();
BindingContext = new MainMenuPageViewModel();
}
}
public class MainMenuPageViewModel : INotifyPropertyChanged
{
public ObservableCollection<MainMenuPageModel> MenuItems { get; set; }
public ICommand LogoutCommand { get; }
public MainMenuPageViewModel()
{
try
{
MenuItems = new ObservableCollection<MainMenuPageModel>(new[]
{
new MainMenuPageModel { Id = 0, Title = "Home", Icon="shop.png", TargetType= typeof(HomePage) },
new MainMenuPageModel { Id = 1, Title = "Profile", Icon="shop.png", TargetType= typeof(ProfilePage) },
new MainMenuPageModel { Id = 2, Title = "Referral History", Icon="paper_money.png", TargetType= typeof(ReferralHistoryPage) },
});
}
catch(Exception ex)
{
Console.WriteLine(ex.Message);
}
}
#region INotifyPropertyChanged Implementation
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged([CallerMemberName] string propertyName = "")
{
if (PropertyChanged == null)
return;
PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}