C# MVVM模式：命令绑定和ViewModel执行之间的中间视图

场景 一些数据被加载到一个程序中（例如，在一个班级中，每个学生都是一个具有他/她的评估数据的独立实体，对学生的评估），并在数据网格上显示这些数据的摘要。用户选择一些学生，并对他们的评估进行分析。分析过程需要一些参数，因此在分析之前会弹出一个窗口，让用户指定自己喜欢的参数；然后执行分析过程

实施总结 datagrid定义如下，并绑定到ViewModel：

<DataGrid x:Name="CachedSamplesDG" ItemsSource="{Binding cachedDataSummary}">                    
   <DataGrid.Columns>
      <DataGridTextColumn Header="name" Binding="{Binding name}"/>
      <DataGridTextColumn Header="score" Binding="{Binding score}"/>
   </DataGrid.Columns>
</DataGrid>

a这是我当前流程的示意图，以及我下一步要做的事情

问题 单击按钮时

在MainWindow上应用一些UI更改

弹出处理选项窗口

从ProcessOptions窗口获取设置参数

将选定的datagrid行和用户指定的参数传递给

SamplesAnalyzeCommand

---

实现此要求的最佳方法是什么？

只需使用dialogservice，如

然后可以在ViewModel中执行类似操作

 var result = this.uiDialogService.ShowDialog("Prozess Options Window", prozessOptionVM);

 ...
 var parameter1 = prozessOptionVM.Parameter1;

---

您可以为流程选项定义另一个模型和ViewModel，然后在SamplesAnalyze命令中显示流程选项视图。当用户完成ProcessOptionView时，主ViewModel会收到通知（例如通过事件处理程序）并完成该过程

大概是这样的：

internal class SamplesAnalyzeCommand : ICommand {
   ...
   public void Execute(object parameter)
   {
       this._viewModel.ShowProcessOptions(parameter);
   }
}

internal class CachedDataSummaryViewModel {
    public string Status {
         get {
             return this.status;
         }
         set {
             if (!string.Equals(this.status, value)) {
                 this.status = value;
                 // Notify property change to UI
             }
         }
    }
    ...
    internal void ShowProcessOptions(object paramter) {
        // Model
        var processOptions = new ProcessOptionsModel() {
            otherInfo = parameter
        };
        // View-Model
        var processOptionsViewModel = new ProcessOptionsViewModel();
        processOptionsViewModel.Model = processOptions;
        // View
        var processOptionsView = new ProcessOptionsView(
            processOptionsViewModel
        );
        // Edit2: Update status
        this.Status = "Selecting process options...";

        // You can use the event handler or dialog result
        processOptionsViewModel.OK += this.PerformProcess;
        processOptionsView.ShowDialog();
    }
    private void PerformProcess(object sender, EventArgs e) {
        var processOptionsView = sender as ProcessOptionsView;
        var processOptionsModel = processOptionsView.Model;
        var processOptions = processOptionsModel.Model;          

        // Edit2: Update status
        this.Status = "Performing process...";

        // use processOptions.OtherInfo for initial info
        // use processOptions.* for process options info
        // and perform the process here

        // Edit2: Update status
        this.Status = "Process Done.";
    }
    ...
}
class ProcessOptionsModel {
    public object OtherInfo {
        get;
        set;

    public int Parameter1 {
        get;
        set;
    }
    public IList<ProcessItem> SelectedItems {
        get;
        set;
    }
    ...
} 
class ProcessOptionsViewModel {
    public event EventHandler OK;
    private SamplesAnalyzeCommand model;
    private ICommand okCommand;
    public ProcessOptionsViewModel() {
         this.okCommand = new OKCommand(this.OnOK);
    }
    public SamplesAnalyzeCommand Model {
        get {
            return model;
        }
        set {
            this.model = value;
            // Property changed stuff here
        }
    }
    private void OnOK(object parameter) {
        if (this.OK != null) {
            this.OK = value;
        }
    }
}
class ProcessOptionsView {
     // Interacts with it's view-model and performs OK command if
     // user pressed OK or something
}

}

请注意，在本例中，我删除了OK事件，因为GetProcessOptions应该一直阻止，直到用户关闭主窗口。如果您希望在FromFile案例中采用响应性方法，那么可能需要处理异步的内容，可以定义getProcessOptionAsync

---

在这种情况下，事情可能会变得有点复杂，但我想通过这种方式是可以实现的。

这是一种好的、实用的方法，但仍然不能完全解决我的问题。我想做的第一件事是在父UI上更改UI。我还想将

选项窗口从
CachedDataSummaryViewModel
中排除。我希望，
CachedDataSummaryViewModel
只包含用户定义的参数，而不管它们来自何处。这使得it独立于获取此类参数的逻辑发生的任何更改（例如，我可以将其更改为从持久化存储器读取），我更新了答案。我希望我明白你的意思。
internal class SamplesAnalyzeCommand : ICommand
    {
        public SamplesAnalyzeCommand(CachedDataSummaryViewModel viewModel)
        {
            _viewModel = viewModel;
        }

        private CachedDataSummaryViewModel _viewModel;

        public event EventHandler CanExecuteChanged
        { 
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public bool CanExecute(object parameter)
        {
            // canExecute logic
        }

        public void Execute(object parameter)
        {
            // process mess ...
            // Here I need the selected rows of datagird, which "parameter" delegates them.
            // I also need some other parameters for analysis which user can set through another view
        }
    }

 var result = this.uiDialogService.ShowDialog("Prozess Options Window", prozessOptionVM);

 ...
 var parameter1 = prozessOptionVM.Parameter1;

internal class SamplesAnalyzeCommand : ICommand {
   ...
   public void Execute(object parameter)
   {
       this._viewModel.ShowProcessOptions(parameter);
   }
}

internal class CachedDataSummaryViewModel {
    public string Status {
         get {
             return this.status;
         }
         set {
             if (!string.Equals(this.status, value)) {
                 this.status = value;
                 // Notify property change to UI
             }
         }
    }
    ...
    internal void ShowProcessOptions(object paramter) {
        // Model
        var processOptions = new ProcessOptionsModel() {
            otherInfo = parameter
        };
        // View-Model
        var processOptionsViewModel = new ProcessOptionsViewModel();
        processOptionsViewModel.Model = processOptions;
        // View
        var processOptionsView = new ProcessOptionsView(
            processOptionsViewModel
        );
        // Edit2: Update status
        this.Status = "Selecting process options...";

        // You can use the event handler or dialog result
        processOptionsViewModel.OK += this.PerformProcess;
        processOptionsView.ShowDialog();
    }
    private void PerformProcess(object sender, EventArgs e) {
        var processOptionsView = sender as ProcessOptionsView;
        var processOptionsModel = processOptionsView.Model;
        var processOptions = processOptionsModel.Model;          

        // Edit2: Update status
        this.Status = "Performing process...";

        // use processOptions.OtherInfo for initial info
        // use processOptions.* for process options info
        // and perform the process here

        // Edit2: Update status
        this.Status = "Process Done.";
    }
    ...
}
class ProcessOptionsModel {
    public object OtherInfo {
        get;
        set;

    public int Parameter1 {
        get;
        set;
    }
    public IList<ProcessItem> SelectedItems {
        get;
        set;
    }
    ...
} 
class ProcessOptionsViewModel {
    public event EventHandler OK;
    private SamplesAnalyzeCommand model;
    private ICommand okCommand;
    public ProcessOptionsViewModel() {
         this.okCommand = new OKCommand(this.OnOK);
    }
    public SamplesAnalyzeCommand Model {
        get {
            return model;
        }
        set {
            this.model = value;
            // Property changed stuff here
        }
    }
    private void OnOK(object parameter) {
        if (this.OK != null) {
            this.OK = value;
        }
    }
}
class ProcessOptionsView {
     // Interacts with it's view-model and performs OK command if
     // user pressed OK or something
}

interface IOptionsProvider {
    ProcessOptionsModel GetProcessOptions();
}

class ProcessOptionsView : IOptionsProvider {
    public ProcessOptionsModel GetProcessOptions() {
         if (this.ShowDialog()) {
              return this.ModelView.Model;
         }
         return null;
    }
}

class ProcessOptionsFromFile : IOptionsProvider {
    public ProcessOptionsModel GetProcessOptions() {
         // Create an instance of ProcessOptionsModel from File
    }