CODEWITHSUNDEEP
c#wpfmvvm
VansFannel
VansFannel

Reputation: 45961

Communication between two user controls (one contains the other) with MVVM

I'm developing a WPF with MVVM, .NET Framework 4.6.1 and C#.

I have two user controlers, one inside the other one:

<Grid x:Name="gridStartBatch" Margin="30" Grid.RowSpan="6" Grid.ColumnSpan="3" Visibility="{Binding GridStartBatchVisibility}">
    <local:StartBatch x:Name="userControlStartBatch" />
</Grid>

I show StartBatch user control changing GridStartBatchVisibility value.

On StartBatchViewModel I have three properties that I want to pass to FirstControlViewModel and also I want to notify FirstControlViewModel to change GridStartBatchVisibility value to hide StartBatch.

Is there anyway to access FirstControlViewModel from StartBatchViewModel?

Upvotes: 0

Views: 251

Answers (1)

StepUp
StepUp

Reputation: 38209

There are many ways to communicate between view models and a lot of points what the point is the best. You can see how it is done:

In my view, the best approach is using EventAggregator pattern of Prism framework. The Prism simplifies MVVM pattern. However, if you have not used Prism, you can use Rachel Lim's tutorial - simplified version of EventAggregator pattern by Rachel Lim. I highly recommend you Rachel Lim's approach.

If you use Rachel Lim's tutorial, then you should create a common class:

public static class EventSystem
{...Here Publish and Subscribe methods to event...}

And publish an event into your OptionViewModel:

eventAggregator.GetEvent<ChangeStockEvent>().Publish(
new TickerSymbolSelectedMessage{ StockSymbol = “STOCK0” });

then you subscribe in constructor of another your MainViewModel to an event:

eventAggregator.GetEvent<ChangeStockEvent>().Subscribe(ShowNews);

public void ShowNews(TickerSymbolSelectedMessage msg)
{
   // Handle Event
}

The Rachel Lim's simplified approach is the best approach that I've ever seen. However, if you want to create a big application, then you should read this article by Magnus Montin and at CSharpcorner with an example.

Upvotes: 2

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