c# - 更改 View Wpf MVVM

我是WPF和MVVM的初学者，但想通过构建一些小项目来学习它。
我有一个基于Rachel Lim示例的使用Model-View-ViewModel模式的WPF应用程序。在我的应用程序中，我有2个 View -EmployeesList和EmployeeDetails。
员工列表存储在GidView中。

我的主要问题是

双击一行

时如何更改 View

如何从第一列(employee_id)中获取值并将其传递到EmployeeDetails View 。

基本导航在带有DataTmplate和ItmCntrol的xaml中:

<Window.Resources>
    <DataTemplate DataType="{x:Type local:HomeViewModel}">
        <local:HomeView />
    </DataTemplate>
    <DataTemplate DataType="{x:Type local:EmployeesListViewModel}">
        <local:EmployeesListView />
    </DataTemplate>
</Window.Resources>



<ItemsControl ItemsSource="{Binding PageViewModels}">
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <Button Content="{Binding Name}"
                    Command="{Binding DataContext.ChangePageCommand, RelativeSource={RelativeSource AncestorType={x:Type Window}}}"
                    CommandParameter="{Binding }"
                    Margin="2,5"/>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

我也有ApplicationViewModel在哪里 View 列表

public class ApplicationViewModel : ObservableObject
{
    #region Fields

    private ICommand _changePageCommand;

    private IPageViewModel _currentPageViewModel;
    private List<IPageViewModel> _pageViewModels;

    #endregion

    public ApplicationViewModel()
    {
        // Add available pages
        PageViewModels.Add(new HomeViewModel());
        PageViewModels.Add(new EmployeesListViewModel());
        PageViewModels.Add(new EmployeeDetailsViewModel());

        // Set starting page
        CurrentPageViewModel = PageViewModels[0];
    }

    #region Properties / Commands

    public ICommand ChangePageCommand
    {
        get
        {
            if (_changePageCommand == null)
            {
                _changePageCommand = new RelayCommand(
                    p => ChangeViewModel((IPageViewModel)p),
                    p => p is IPageViewModel);
            }

            return _changePageCommand;
        }
    }

    public List<IPageViewModel> PageViewModels
    {
        get
        {
            if (_pageViewModels == null)
                _pageViewModels = new List<IPageViewModel>();

            return _pageViewModels;
        }
    }

    public IPageViewModel CurrentPageViewModel
    {
        get
        {
            return _currentPageViewModel;
        }
        set
        {
            if (_currentPageViewModel != value)
            {
                _currentPageViewModel = value;
                OnPropertyChanged("CurrentPageViewModel");
            }
        }
    }

    #endregion

    #region Methods

    private void ChangeViewModel(IPageViewModel viewModel)
    {
        if (!PageViewModels.Contains(viewModel))
            PageViewModels.Add(viewModel);

        CurrentPageViewModel = PageViewModels
        .FirstOrDefault(vm => vm == viewModel);
    }

    #endregion
}

最佳答案

双击行时如何更改 View

首先，您需要为MouseDoubleClick事件添加EventTrigger:

    <DataGrid Name="gridEmployees" ItemsSource="{Binding Employees}">
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="MouseDoubleClick">
                <local:CustomCommandAction Command="{Binding DoubleClickCommand}" CommandParameter="{Binding ElementName=gridEmployees, Path=SelectedItems[0]}" />
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </DataGrid>

CustomCommandAction是一个类，它继承自TriggerAction，并用作 View 模型中事件和命令之间的链接。这是代码:

public sealed class CustomCommandAction : TriggerAction<DependencyObject>
{
    public static readonly DependencyProperty CommandParameterProperty =
        DependencyProperty.Register("CommandParameter", typeof(object), typeof(CustomCommandAction), null);

    public static readonly DependencyProperty CommandProperty = DependencyProperty.Register(
        "Command", typeof(ICommand), typeof(CustomCommandAction), null);

    public ICommand Command
    {
        get
        {
            return (ICommand)this.GetValue(CommandProperty);
        }
        set
        {
            this.SetValue(CommandProperty, value);
        }
    }

    public object CommandParameter
    {
        get
        {
            return this.GetValue(CommandParameterProperty);
        }

        set
        {
            this.SetValue(CommandParameterProperty, value);
        }
    }

    protected override void Invoke(object parameter)
    {
        if (this.AssociatedObject != null)
        {
            ICommand command = this.Command;
            if (command != null)
            {
                if (this.CommandParameter != null)
                {
                    if (command.CanExecute(this.CommandParameter))
                    {
                        command.Execute(this.CommandParameter);
                    }
                }
                else
                {
                    if (command.CanExecute(parameter))
                    {
                        command.Execute(parameter);
                    }
                }
            }
        }
    }
}

之后，最简单的解决方案是在您的命令Execute方法中使用ChangeViewModel方法，例如:

...

_doubleClickCommand = new RelayCommand(OnDoubleClick);
...

    private RelayCommand _doubleClickCommand = null;
    private ApplicationViewModel _applicationViewModel;

    private void OnDoubleClick(object obj)
    {
        EmployeeDetailsViewModel selectedModel = obj as  EmployeeDetailsViewModel;

        _applicationViewModel.ChangeViewModel(selectedModel);
    }

    public ICommand DoubleClickCommand
    {
        get
        {
            return _doubleClickCommand;
        }
    }

如何从第一列(employee_id)获取值并将其传递到EmployeeDetails View

对于您的DataGrid，您可以使用EmployeeDetailsViewModel的集合作为ItemsSource。如果这样做，所选项目将作为EmployeeDetailsViewModel的实例传递到命令Execute方法，您将能够从那里获取ID。

关于c# - 更改 View Wpf MVVM，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/34807591/