Xamarin.Forms FlyoutPage无法使用Prism

Question

请帮帮我。为了让你理解我的问题，我在示例应用程序中复制了这个场景

由于Xamarin.Forms在5.0版本中引入了FlyoutPage页面，导航在其中一个应用程序中不起作用。我正在从app.xaml.cs打开主页，就像这个await NavigationService.NavigateAsync("Page3");

传单页面：

<FlyoutPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:views="clr-namespace:PrismNavigation.Views;assembly=PrismNavigation"
xmlns:prism="http://prismlibrary.com"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="PrismNavigation.Views.Page3"
Title="Master">
<FlyoutPage.Flyout>
<ContentPage Title="Menu">
<StackLayout>
<Button Text="Page2" HeightRequest="50" WidthRequest="100" Command="{Binding NavigateCommand}" CommandParameter="Page2"></Button>
</StackLayout>
</ContentPage>
</FlyoutPage.Flyout>
<FlyoutPage.Detail>
<NavigationPage>
<x:Arguments>
<views:Page1></views:Page1>
</x:Arguments>
</NavigationPage>
</FlyoutPage.Detail>
</FlyoutPage>

Page3ViewModel:

using Prism.Commands;
using Prism.Mvvm;
using Prism.Navigation;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace PrismNavigation.ViewModels
{
public class Page3ViewModel : ViewModelBase
{
private readonly INavigationService navigationService;

public Page3ViewModel(
INavigationService navigationService)
: base(navigationService)
{
this.navigationService = navigationService;
this.NavigateCommand = new DelegateCommand<string>(this.NavigateCommandExecute);
}

public override void OnNavigatedTo(INavigationParameters parameters)
{
base.OnNavigatedTo(parameters);
}

private void NavigateCommandExecute(string obj)
{
this.navigationService.NavigateAsync($"NavigationPage/{obj}");
}

public DelegateCommand<string> NavigateCommand { get; set; }
}
}

应用程序：

using Prism;
using Prism.Ioc;
using PrismNavigation.ViewModels;
using PrismNavigation.Views;
using Xamarin.Essentials.Implementation;
using Xamarin.Essentials.Interfaces;
using Xamarin.Forms;

namespace PrismNavigation
{
public partial class App
{
public App(IPlatformInitializer initializer)
: base(initializer)
{
}

protected override async void OnInitialized()
{
InitializeComponent();
await NavigationService.NavigateAsync("Page3");
}

protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
containerRegistry.RegisterSingleton<IAppInfo, AppInfoImplementation>();

containerRegistry.RegisterForNavigation<NavigationPage>();              
containerRegistry.RegisterForNavigation<Page1>();
containerRegistry.RegisterForNavigation<Page2>();
containerRegistry.RegisterForNavigation<Page3, Page3ViewModel>();
}
}
}

当我试图从菜单导航到Page2时，我无法做到这一点。当我单击按钮时，会执行导航命令，但不会进行导航。

Answer 1

更新：除了你在问题中固定的我的旧答案之外，根据这一点，Prism 8似乎不支持FlyoutPage。计划为8.1。因此，您可以等待8.1或将其替换为MasterDetailPage。我用MasterDetailPage尝试了你的例子，它对我来说很好：

<?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:prism="http://prismlibrary.com"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="PrismNavigation.Views.Page3">
<MasterDetailPage.Master>
<ContentPage Title="Menu">
<StackLayout Padding="20">
<Button Text="Page2" HeightRequest="50" WidthRequest="100" Command="{Binding NavigateCommand}" CommandParameter="Page2"></Button>
</StackLayout>
</ContentPage>
</MasterDetailPage.Master>

<MasterDetailPage.Detail>
<NavigationPage>
<x:Arguments>
<ContentPage Title="This is Page1"></ContentPage>
</x:Arguments>
</NavigationPage>
</MasterDetailPage.Detail>

</MasterDetailPage>

旧答案：似乎您没有向NavigateCommand传递任何参数。试试这个

<StackLayout>
<Button Text="Page2" HeightRequest="50" WidthRequest="100" Command="{Binding NavigateCommand}" CommandParameter="Page2"></Button>
</StackLayout>