棱鏡如何找到視圖文件夾的子文件夾中的視圖

Question

我正在學習windows store應用程序中的棱鏡。我遇到了問題。我有很多意見，我想將它們分成不同的文件夾。但問題在於NavigationService無法找到它們。說明書說，所有視圖顯示放入視圖文件夾，然後導航服務可以使用navigationservice.navigate（「main」，null）導航到它們，但是如果視圖不在導航服務找不到它們的視圖文件夾的根目錄

Answer 1

NavigationService根據約定查找Views和ViewModels。所有視圖必須位於「視圖」文件夾中，並且ViewModels必須位於「ViewModels」文件夾中。如果ID不適合你可以做到以下幾點：

1. 添加下面的類到你的項目：

   public class ViewViewModelTypeResolver 
   { 
       private const string ViewNameSuffix = "Page"; // You can change this View name suffix 
       private const string ViewModelNameSuffix = "ViewModel"; // You can change this ViewModel name suffix 
   
       private readonly Lazy<Dictionary<string, Type>> _uiAssemblyExportedTypes; 
   
       private Dictionary<string, Type> UiAssemblyExportedTypes 
       { 
        get { return _uiAssemblyExportedTypes.Value; } 
       } 
   
       public ViewViewModelTypeResolver(Type typeFromUiAssembly) 
       { 
        _uiAssemblyExportedTypes = new Lazy<Dictionary<string, Type>>(() => GetUiAssemblyExportedTypes(typeFromUiAssembly)); 
       } 
   
       public Type GetViewType(string viewTypeName) 
       { 
        return UiAssemblyExportedTypes[viewTypeName]; 
       } 
   
       public Type GetViewModelType(Type viewType) 
       { 
        var pageNameWithoutSuffix = viewType.Name.Remove(viewType.Name.LastIndexOf(ViewNameSuffix, StringComparison.Ordinal)); 
        var viewModelName = String.Concat(pageNameWithoutSuffix, ViewModelNameSuffix); 
        return UiAssemblyExportedTypes[viewModelName]; 
       } 
   
   
       private static Dictionary<string, Type> GetUiAssemblyExportedTypes(Type typeFromUiAssembly) 
       { 
        return typeFromUiAssembly.GetTypeInfo().Assembly.ExportedTypes.ToDictionary(type => type.Name, type => type, StringComparer.Ordinal); 
       } 
   } 
   

2. 添加ViewViewModelTypeResolver到App構造函數：

   public App() 
   { 
       var mainPage = typeof(MainPage); // Any of pages from your solution. Pay attention that the resolver will be able to resolve Views and ViewModels that locates in the same project as specified page. 
       _viewViewModelTypeResolver = new ViewViewModelTypeResolver(mainPage); 
   } 
   

3. 當你使用Prism時，我假設你從MvvmAppBase繼承你的App類。如果是這樣，你應該重寫GetPageType方法：

   protected override Type GetPageType(string pageToken) 
       { 
        return _viewViewModelTypeResolver.GetViewType(pageToken); 
       } 
   

4. 然後在OnInitializeAsync方法添加SetDefaultViewTypeToViewModelTypeResolver：

   protected override async Task OnInitializeAsync(IActivatedEventArgs args) 
   { 
       // Your initialization code 
   
       ViewModelLocationProvider.SetDefaultViewTypeToViewModelTypeResolver(GetViewModelType); 
   
       // Your initialization code 
   } 
   
   private Type GetViewModelType(Type pageType) 
   { 
       return _viewViewModelTypeResolver.GetViewModelType(pageType); 
   } 
   

現在你可以瀏覽到任何網頁上，即使它們被分成不同的文件夾。

Answer 2

來自Alexander.Ermolaev的很好回答。我想擴展他的課程以滿足我的需求。我不喜歡公開所有的ViewModel。當我們真正需要的是Views和ViewModels的類型時，我也不想保留所有類型的字典。這將查找從UserControl繼承的所有視圖，因爲ViewModelLocator將與UserControl以及Pages一起使用。這將找到所有從基本視圖模型類繼承的ViewModel，通常是Prism的ViewModelBase。從App.cs

sealed class ViewViewModelTypeResolver 
{ 
    private readonly Assembly _assembly; 
    private readonly Type _baseViewModelType; 
    private readonly string _viewNameSuffix; 
    private readonly string _viewModelNameSuffix; 
    private readonly Lazy<Dictionary<string, Type>> _views; 
    private readonly Lazy<Dictionary<string, Type>> _viewModels; 

    private Dictionary<string, Type> Views => _views.Value; 
    private Dictionary<string, Type> ViewModels => _viewModels.Value; 

    /// <summary> 
    /// Resolves Views and ViewModels. 
    /// </summary> 
    /// <param name="typeFromUiAssembly">Use any type from the UI Assembly.</param> 
    /// <param name="baseViewModelType">All view models need to inherit from this type.</param> 
    /// <param name="viewNameSuffix">Prism convention is to name your views with a Page suffix.</param> 
    /// <param name="viewModelNameSuffix">Prism convention is name your viewmodels with a ViewModel suffix.</param> 
    public ViewViewModelTypeResolver(Type typeFromUiAssembly, Type baseViewModelType, string viewNameSuffix = "Page", string viewModelNameSuffix = "ViewModel") 
    { 
     _baseViewModelType = baseViewModelType; 
     _viewNameSuffix = viewNameSuffix; 
     _viewModelNameSuffix = viewModelNameSuffix; 
     _assembly = typeFromUiAssembly.GetTypeInfo().Assembly; 

     _views = new Lazy<Dictionary<string, Type>>(GetViews); 
     _viewModels = new Lazy<Dictionary<string, Type>>(GetViewModels); 
    } 

    /// <summary> 
    /// Gets a View type for the given name. 
    /// </summary> 
    /// <param name="viewTypeName">Name of the view without the suffix.</param> 
    public Type GetViewType(string viewTypeName) 
    { 
     var pageName = string.Concat(viewTypeName, _viewNameSuffix); 
     return this.Views[pageName]; 
    } 

    /// <summary> 
    /// Gets a ViewModel for the given view type. 
    /// </summary> 
    /// <param name="viewType">Type of view.</param> 
    public Type GetViewModelType(Type viewType) 
    { 
     var viewModelName = string.Concat(viewType.Name, _viewModelNameSuffix); 
     return this.ViewModels[viewModelName]; 
    } 

    /// <summary> 
    /// Gets all the View types by finding all types that inherit from Page and are defined in the UI Assembly. 
    /// </summary> 
    private Dictionary<string, Type> GetViews() 
    { 
     var types = _assembly.DefinedTypes.Where(type => !type.IsAbstract && type.IsSubclassOf(typeof(UserControl))); 

     return types.ToDictionary(typeInfo => typeInfo.Name, typeInfo => typeInfo.AsType(), StringComparer.Ordinal); 
    } 

    /// <summary> 
    /// Gets all the ViewModel types by finding all types that inherit from a base ViewModel type defined in the UI Assembly. 
    /// </summary> 
    private Dictionary<string, Type> GetViewModels() 
    { 
     var types = _assembly.DefinedTypes.Where(type => !type.IsAbstract && type.IsSubclassOf(_baseViewModelType)); 

     return types.ToDictionary(typeInfo => typeInfo.Name, typeInfo => typeInfo.AsType(), StringComparer.Ordinal); 
    } 
} 

用法：

private readonly ViewViewModelTypeResolver _viewViewModelTypeResolver; 

public App() 
{ 
    this.InitializeComponent(); 

    _viewViewModelTypeResolver = new ViewViewModelTypeResolver(this.GetType(), typeof(ViewModelBase)); 
} 

//other methods are the same as Alexander's answer. 

感謝亞歷山大，你的代碼對我來說是很好的起點。