使用MVVM进行WPF帧导航绑定 [英] WPF Frame Navigation Binding with MVVM

问题描述

大家好我有一个使用MVM模式的WPF应用程序。在应用程序中，我有一个框架来托管我的页面a和b，但是当我将视图从页面a更改为b，并尝试将我的视图更改回页面a时，它不会为我带来新页面而是会带回页面一个与旧的国家。我怎么能阻止它？下面是我的xaml和视图模型的代码



xaml

 <   MenuItem    标题  = 运算符   可见性  =  {绑定路径= MenuVisibility，Converter = {StaticResource BooleanToVisibilityConverter}}  
   
                          < span class =code-attribute>                            命令  =  {Binding Path = ViewMenuCommand}    /  >  
 
 <  框架    Grid.Row   =  1   名称  =  MainAPpFrame    NavigationUIVisibility   = 隐藏  
   
                                  来源  =  {Binding Path = DisplayPage，Mode = TwoWay}    Horizo​​ntalContentAlignment   = 拉伸    VerticalContentAlignment   = 拉伸    /  >  

我的视图模型

 私人页面displayPage; 
 
  public 页面DisplayPage 
 {
  get  
 {
  return  displayPage; 
} 
  set  
 {
  if （displayPage ==  value ）
 {
  return ; 
} 
 
 此 .displayPage =  value ; 
  base  .OnPropertyChanged（  DisplayPage< /跨度>）; 
} 
} 
 
  public  ICommand ViewMenuCommand 
 {
  get  
 {
  if （_operatorViewMenuCommand ==  null ）
 {
 _operatorViewMenuCommand =  new  RelayCommand（
 param = >   this  .ProcessNavRequest（））; 
} 
  return  _operatorViewMenuCommand; 
} 
} 
 
 私有  void  ProcessNavRequest（ ）
 {
  //   string uri = String.Format（/ View / {0} ，参数）;  
 此 .DisplayPage =  new  OperatorView（）; 
} 

解决方案

 private Page _displayPage; 
 
 public Page DisplayPage 
 {
 get 
 {
 return _displayPage; 
} 
设置
 {
 if（等于（_displayPage，value））
 {
 return; 
} 
 
 this._displayPage = value; 
 OnPropertyChanged（DisplayPage）; 
} 
} 
 
 
 private RelayCommand _operatorViewMenuCommand; 
 public ICommand ViewMenuCommand 
 {
 get 
 {
 if（_operatorViewMenuCommand == null）
 {
 _operatorViewMenuCommand = new RelayCommand（param => ; this.ProcessNavRequest（DisplayPage））; 
} 
返回_operatorViewMenuCommand; 
} 
} 
 public void ProcessNavRequest（Page page）
 {
 // string uri = String.Format（/ View / {0}，参数） ; 
 this.DisplayPage = page; 
} 
 

我来自myCommand打电话

 StartScreenViewModel.ProcessNavRequest（new ImportForm（））; 

但它不记得导航

Hi guys I have a WPF application that is using MVM pattern. In the application I have a frame that host my page a and b, however when I change view from page a to b, and try to change my view back to page a, it does not bring me a new page instead it brings back page a with its old state. How can I stop that? Below is my code for both my xaml and view model

xaml

<MenuItem Header="Operator" Visibility="{Binding Path=MenuVisibility, Converter={StaticResource BooleanToVisibilityConverter}}"

                          Command="{Binding Path=ViewMenuCommand}" />

<Frame Grid.Row="1" Name="MainAPpFrame" NavigationUIVisibility="Hidden"

                Source="{Binding Path=DisplayPage, Mode=TwoWay}" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" />

my view model

private Page displayPage;

        public Page DisplayPage
        {
            get
            {
                return displayPage;
            }
            set
            {
                if (displayPage == value)
                {
                    return;
                }

                this.displayPage = value;
                base.OnPropertyChanged("DisplayPage");
            }
        }

public ICommand ViewMenuCommand
        {
            get
            {
                if (_operatorViewMenuCommand == null)
                {
                    _operatorViewMenuCommand = new RelayCommand(
                        param => this.ProcessNavRequest());
                }
                return _operatorViewMenuCommand;
            }
        }

private void ProcessNavRequest()
        {
            //string uri = String.Format("/View/{0}", parameter);
            this.DisplayPage = new OperatorView();
        }

解决方案

private Page _displayPage;

       public Page DisplayPage
       {
           get
           {
               return _displayPage;
           }
           set
           {
               if (Equals(_displayPage, value))
               {
                   return;
               }

               this._displayPage = value;
               OnPropertyChanged("DisplayPage");
           }
       }


       private RelayCommand _operatorViewMenuCommand;
       public ICommand ViewMenuCommand
       {
           get
           {
               if (_operatorViewMenuCommand == null)
               {
                   _operatorViewMenuCommand = new RelayCommand(param => this.ProcessNavRequest(DisplayPage));
               }
               return _operatorViewMenuCommand;
           }
       }
       public void ProcessNavRequest(Page page)
       {
           //string uri = String.Format("/View/{0}", parameter);
           this.DisplayPage = page;
       }

I call from myCommand

StartScreenViewModel.ProcessNavRequest(new ImportForm());

But it does not remember the navigation

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