How to open new window in ReactiveUI with params

user_12248263 0
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I'm searching the best way to open new window with params respecting the MVVM ReactiveUi principles. Now I'm using Splat's Service Location to open new window. Suppose that I want to open new window when I click a button on MainWindow View. Currently:

  1. I call the Locator.Current.GetService("WindowToOpen") in the method of ViewModel that manage MainWindow View, for get the instance of the window to open
  2. I call the Show or ShowDialog method of the instance "WindowToOpen"

But how should I do if I want to pass a parameter to the "WindowToOpen"?

Thanks

reactiveui wpf c#
1 Answers

I also could not find any examples on how to open a new window with ReactiveUI in WPF.

What I ended up doing was adding a dependency property to my views (since you cannot pass in parameters to view constructors). If, for example, you need to pass in the string value userName to a new window you would have to add the following dependency property to that view class:

public static readonly DependencyProperty UserNameProperty =
    DependencyProperty.Register("UserName", typeof(string), typeof(YourView),
        new PropertyMetadata(default(string)));

public string UserName
{
    get => (string) GetValue(UserNameProperty);
    set => SetValue(UserNameProperty, value);
}

then, when creating the view, you can assign a value to that property. In your case:

Window window = Locator.Current.GetService("WindowToOpen") as Window;
window.PropertyToChange = valueOfProperty;
window.Show();

If you need the property value in your view model (which you probably do if you're using MVVM), bind the dependency property to a property in your view model. This has to be done in the view's WhenActivated method:

this.WhenActivated(disposables =>
{
    // Instantiate the view model just in case it is null
    ViewModel ??= Locator.Current.GetService<YourView>() ??
                  throw new InvalidOperationException("YourViewis not registered.");

    this.WhenAnyValue(view => view.UserName)
        .BindTo(ViewModel, viewModel => viewModel.UserName)
        .DisposeWith(disposables);

    // other bindings
});

I know all this feels very clunky and messy. But I have not managed to find any examples on how to do it properly using just ReactiveUI.

user_67350350
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