从Windows 8.1手机通用的应用程序的视图模型导航到一个新页面 [英] Navigating to a new page from the View Model in Windows Phone 8.1 universal app

问题描述

我工作的一款Windows Phone 8.1通用的应用程序，并希望找到处理页面导航的最佳途径，而无需在代码中大量的逻辑背后。我想在我查看整齐地背后保持代码。什么是响应一个按钮，点击导航到新页面的接受MVVM方式？

I am working on a windows phone 8.1 universal app and want to find the best way of handling page navigations without having large amounts of logic in the code behind. I want to keep the code behind in my View as uncluttered as possible. What is the accepted MVVM way of navigating to a new page in response to a button click?

目前，我有从视图模型发送RelayComnmand信息与观点页面细节导航到。这意味着，后面的代码已经进行接线如下：

I currently have to send a RelayComnmand message from the ViewModel to the view with the details of the page to navigate to. This means that the code behind has to be wired up as follows:

    public MainPage()
    {
      InitializeComponent();
      Messenger.Default.Register<OpenArticleMessage>(this, (article) => ReceiveOpenArticleMessage(article));
...
}

    private object ReceiveOpenArticleMessage(OpenArticleMessage article)
    {
     Frame.Navigate(typeof(ArticleView));
   }

这只是似乎不是最好的方法，虽然它的工作。我怎么能直接从视图模型做页面导航？我使用MVVM，光在我的项目。

This just doesn't seem the best way although it does work. How can I do the page navigations directly from the ViewModel? I am using MVVM-Light in my project.

推荐答案

好吧，我已经找到了这个问题的答案。采取了一些调查，但我最终发现这样做的首选MVVM光强的方法。我不邀功这个答案反正只是张贴在这里的情况下，人们都在寻找一个答案

Ok, I have found an answer to this question. Took a bit of investigation but I eventually found the preferred MVVM-Light way of doing this. I don't take credit for this answer in anyway but just posting it here in case people are looking for an answer to this question.

创建INavigationService界面如下：

Create an INavigationService interface as follows:

public interface INavigationService
{
    void Navigate(Type sourcePageType);
    void Navigate(Type sourcePageType, object parameter);
    void GoBack();
}

创建的NavigationService类，如下所示：

Create a NavigationService class as follows:

public class NavigationService : INavigationService
{
    public void Navigate(Type sourcePageType)
    {
        ((Frame)Window.Current.Content).Navigate(sourcePageType);
    }

    public void Navigate(Type sourcePageType, object parameter)
    {
        ((Frame)Window.Current.Content).Navigate(sourcePageType, parameter);
    }

    public void GoBack()
    {
        ((Frame)Window.Current.Content).GoBack();
    }
}

现在在ViewModelLocator，设置它是这样的：

Now in the ViewModelLocator, set it up like this:

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance",
        "CA1822:MarkMembersAsStatic",
        Justification = "This non-static member is needed for data binding purposes.")]
    public MainViewModel Main
    {
        get
        {
            return ServiceLocator.Current.GetInstance<MainViewModel>();
        }
    }

    static ViewModelLocator()
    {
        ServiceLocator.SetLocatorProvider(() => SimpleIoc.Default);

        if (ViewModelBase.IsInDesignModeStatic)
        {
            SimpleIoc.Default.Register<INavigationService, Design.DesignNavigationService>();
        }
        else
        {
            SimpleIoc.Default.Register<INavigationService>(() => new NavigationService());
        }

        SimpleIoc.Default.Register<MainViewModel>();
    }

下一步设置为设计时导航服务如下：

Next setup a navigation service for design time as follows:

public class DesignNavigationService : INavigationService
{
    // This class doesn't perform navigation, in order
    // to avoid issues in the designer at design time.

    public void Navigate(Type sourcePageType)
    {
    }

    public void Navigate(Type sourcePageType, object parameter)
    {
    }

    public void GoBack()
    {
    }
}

我MainViewModel构造如下：

My MainViewModel constructor is as follows:

   public MainViewModel(INavigationService navigationService)
    {
        _navigationService = navigationService;

        ...

现在你可以简单地使用这个在浏览您的视图模型：

Now you can simply use this to navigate in your viewmodel:

_navigationService.Navigate(typeof(WelcomeView));

有关原作者洛朗•比尼翁更多详细信息请参阅本文以及相关的代码。
http://msdn.microsoft.com/en-us/magazine/jj651572.aspx

For more details on the original author Laurent Bugnion see this article and associated code. http://msdn.microsoft.com/en-us/magazine/jj651572.aspx

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