I'll explain how to display a dialog screen (a separate window) using **WPF Prism** in C#.


## Target Files (Example)

The files you need to code are **A through D** below.

```text
Views/
 |-MainWindowView.xaml（画面遷移元）　･･･A
 |-SampleTableEditView.xaml(画面遷移先)

ViewModels/
 |-MainWindowViewModel.cs（画面遷移元）　･･･B
 |-SampleTableEditViewModel.cs(画面遷移先)　･･･C　

App.xaml.cs　･･･D
```

## MainWindowView.xaml (source of navigation) ･･･A

### ①Add a Command to the button

For the button on the View that navigation starts from, add the delegate command name via Binding on Command.

```xml
<Button Content="SampleTable編集"
        FontSize="14"
        Margin="10"
        Padding="5"
        Command="{Binding SampleTableEditViewButton}"/>
```

## MainWindowViewModel.cs (source of navigation) ･･･B

### ②Add an IDialogService field to the ViewModel

Add a private `IDialogService` field to the ViewModel that navigation starts from, and set it in the constructor.

### ③Add the method that runs when the button is pressed

Add the delegate command property that receives the button-press event, and implement the Execute method for when the button is pressed.

The sample code for ② and ③ above is as follows.

```cs
//// コンストラクタ
public MainWindowViewModel(IDialogService dialogService)
{
    //// 画面遷移用（ダイアログ）
    _dialogService = dialogService;

    SampleTableEditViewButton = new DelegateCommand(SampleTableEditViewButtonExecute);
}

public DelegateCommand SampleTableEditViewButton { get; }

private void SampleTableEditViewButtonExecute()
{
    //// 画面遷移処理（ダイアログ）
    _dialogService.ShowDialog(nameof(SampleTableEditView), null, null);
}
```

## SampleTableEditViewModel.cs (navigation destination) ･･･C　

### ④Implement the IDialogAware interface
Implement the **IDialogAware interface** on the ViewModel that is the navigation destination.

### ⑤Change the CanCloseDialog method
Implementing IDialogAware adds the `CanCloseDialog()` method — write `return true` in it.
Returning `true` makes it possible to close the dialog.

▼Sample code for ④ and ⑤ above
```cs
public class SampleTableEditViewModel : BindableBase, IDialogAware
{

  //// 各種処理

  public bool CanCloseDialog()
  {
      return true;    //// true:画面を閉じる事が可能
  }
}
```

## App.xaml.cs　･･･D

### ⑥Register the View inside RegisterTypes

```cs
protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
    //// ダイアログ画面（別画面に表示） ※ViewModelにIDialogAware実装が必要
    containerRegistry.RegisterDialog<SampleTableEditView, SampleTableEditViewModel>();

}
```

Any View registered with `containerRegistry.RegisterDialog` becomes displayable as a dialog.