WPF中模型視圖和視圖模型之間的關係

我已經使用MVVM創建了登錄身份驗證，並且它工作正常。這是我做了什麼：WPF中模型視圖和視圖模型之間的關係

MainWinodw.xaml

<Window.Resources> 
    <BooleanToVisibilityConverter x:Key="BoolToVis" /> 
</Window.Resources> 
<Grid> 
    <Grid.ColumnDefinitions> 
     <ColumnDefinition /> 
     <ColumnDefinition /> 
    </Grid.ColumnDefinitions> 
    <Grid.RowDefinitions> 
     <RowDefinition Height="Auto" /> 
     <RowDefinition Height="Auto" /> 
     <RowDefinition Height="Auto" /> 
     <RowDefinition Height="Auto" /> 
    </Grid.RowDefinitions> 
    <TextBlock Grid.Row="0" Grid.Column="0">UserName:</TextBlock> 
    <TextBlock Grid.Row="1" Grid.Column="0">Password:</TextBlock> 
    <TextBox Grid.Row="0" Grid.Column="1" Text="{Binding UserName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" /> 
    <TextBox Grid.Row="1" Grid.Column="1" Text="{Binding Password, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" /> 
    <Label Grid.Row="3" Grid.ColumnSpan="2" Visibility="{Binding isAuthenticated, Converter={StaticResource BoolToVis}}"> 
     User has been authenticated 
    </Label> 
    <Label Grid.Row="3" Grid.ColumnSpan="2" Visibility="{Binding LoginFail, Converter={StaticResource BoolToVis}}"> 
     Please enter valid UserName and Password 
    </Label> 

    <Button Grid.Row="2" Grid.Column="1" Content="Authenticate" Command="{Binding LoginCommand}" Margin="3" Width="100" HorizontalAlignment="Right" /> 
</Grid>

UserViewModel.cs

public class LoginViewModel : INotifyPropertyChanged 
{ 
    private bool _isAuthenticated; 
    public bool isAuthenticated 
    { 
     get { return _isAuthenticated; } 
     set 
     { 
      if (value != _isAuthenticated) 
      { 
       _isAuthenticated = value; 
       OnPropertyChanged("isAuthenticated"); 
      } 
     } 
    } 

    private bool _loginFail; 
    public bool LoginFail 
    { 
     get { return _loginFail; } 
     set 
     { 
      if (value != _loginFail) 
      { 
       _loginFail = value; 
       OnPropertyChanged("LoginFail"); 
      } 
     } 
    } 

    private string _username; 
    public string UserName 
    { 
     get { return _username; } 
     set 
     { 
      _username = value; 
      OnPropertyChanged("UserName"); 
     } 
    } 

    private string _password; 
    public string Password 
    { 
     get { return _password; } 
     set 
     { 
      _password = value; 
      OnPropertyChanged("Password"); 
     } 
    } 

    public ICommand LoginCommand 
    { 
     get { return new RelayCommand(param => this.Login()); } 
    } 

    public void Login() 
    { 
     //TODO check username and password vs database here. 
     //If using membershipprovider then just call Membership.ValidateUser(UserName, Password) 
     //if (!String.IsNullOrEmpty(UserName) && !String.IsNullOrEmpty(Password)) 
     // isAuthenticated = true; 
     isAuthenticated = LoginDataLayer.AuthenticateUser(UserName, Password); 
     if(isAuthenticated == true) 
     { 
      LoginFail = false; 
     } 
     else 
     { 
      LoginFail = true; 
     } 

    } 

    #region INotifyPropertyChanged Methods 

    public void OnPropertyChanged(string propertyName) 
    { 
     this.OnPropertyChanged(new PropertyChangedEventArgs(propertyName)); 
    } 

    protected virtual void OnPropertyChanged(PropertyChangedEventArgs args) 
    { 
     if (this.PropertyChanged != null) 
     { 
      this.PropertyChanged(this, args); 
     } 
    } 


    public event PropertyChangedEventHandler PropertyChanged; 

    #endregion 
}

這是工作的罰款。但正如我所說我是MVVM的新手。我也在viewmodel中編寫模型代碼。意識到我的錯誤後，我想這樣的分離模型和視圖模型代碼：

UserModel.cs

public class UserModel : INotifyPropertyChanged 
{ 
    private bool _isAuthenticated; 
    public bool isAuthenticated 
    { 
     get { return _isAuthenticated; } 
     set 
     { 
      if (value != _isAuthenticated) 
      { 
       _isAuthenticated = value; 
       OnPropertyChanged("isAuthenticated"); 
      } 
     } 
    } 

    private bool _loginFail; 
    public bool LoginFail 
    { 
     get { return _loginFail; } 
     set 
     { 
      if (value != _loginFail) 
      { 
       _loginFail = value; 
       OnPropertyChanged("LoginFail"); 
      } 
     } 
    } 

    private string _username; 
    public string UserName 
    { 
     get { return _username; } 
     set 
     { 
      _username = value; 
      OnPropertyChanged("UserName"); 
     } 
    } 

    private string _password; 
    public string Password 
    { 
     get { return _password; } 
     set 
     { 
      _password = value; 
      OnPropertyChanged("Password"); 
     } 
    } 

    #region INotifyPropertyChanged Methods 

    public void OnPropertyChanged(string propertyName) 
    { 
     this.OnPropertyChanged(new PropertyChangedEventArgs(propertyName)); 
    } 

    protected virtual void OnPropertyChanged(PropertyChangedEventArgs args) 
    { 
     if (this.PropertyChanged != null) 
     { 
      this.PropertyChanged(this, args); 
     } 
    } 


    public event PropertyChangedEventHandler PropertyChanged; 

    #endregion 
}

UserViewModel.cs

public void Login() 
    { 
     UserModel obj = new UserModel(); 


     obj.isAuthenticated = LoginDataLayer.AuthenticateUser(obj.UserName,obj. Password); 
     if(obj.isAuthenticated == true) 
     { 
      obj.LoginFail = false; 
     } 
     else 
     { 
      obj.LoginFail = true; 
     } 

    }

但我正在逐漸obj.username爲空。那麼任何人都可以幫助我如何在視圖模型中獲取模型屬性，以及如何更新模型屬性。請幫忙。謝謝

來源

2016-07-22 Neelam Prajapati

我不認爲thatr你不能讓你的邏輯都在一起。在ViewModel中使用方法不成問題。您可以繼續使用您的方法 – Apoorv

，但我在許多網站上閱讀，模型和視圖模型必須是分開的。 –

確定做一件事..在您的UserViewModel.cs中替換UserModel obj = new UserModel（）與ObservableCollection coll = new ObservableCollection （）;然後嘗試訪問這些值並查看您是否仍然收到空值？ – Apoorv

正如我所看到的，您的視圖datacontext是viewModel，但屬性在Model上。讓你的usermodel從視圖模型入店，像這樣：

視圖模型：

private UserModel _userModel; 
public UserModel userModel 
{ 
    get { return _userModel; } 
    set 
    { 
     _userModel = value; 
     OnPropertyChanged("userModel"); 
    } 
}

查看：

<TextBox Text="{Binding userModel.UserName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />

來源

2016-07-22 06:52:26 Jose

WPF中模型視圖和視圖模型之間的關係

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