Bind to IReactiveCommand in view code behind

Question

I have my ViewModel which has an ErrorCommand. I wish to subscribe to this in my view code behind so that any time it is called I can display an error message which is passed like so:

ErrorCommand.Exectute("Error occured")

In the view:

this.WhenAny(view => x.ViewModel.ErrorCommand, x => x.Value).Subscribe(error => DisplayError(error));

This code doesn't actually work but hopefully shows what I'm trying to acheive. How would I do this correctly?

I understand I could use the MessageBus, but I also have a similar scenario where the MessageBus wouldn't be appropriate.

score 2 · Accepted Answer · answered Jul 18 '13 at 04:12

2

There's a method specifically for this scenario:

this.WhenAnyObservable(x => x.ViewModel.ErrorCommand).Subscribe(x => /* ... */);

will do what you expect and will avoid the null refs

answered Jul 18 '13 at 04:12

Ana Betts

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score 0 · Answer 2 · answered Jul 17 '13 at 13:50

0

this.WhenAny(view => x.ViewModel.ErrorCommand, x => x.Value).Subscribe(error => DisplayError(error));

Will only fire when you change the value of the ErrorCommand property.

What you want is this:

ViewModel.ErrorCommand.IsExecuting.Subscribe(x=> DisplayError(x));

answered Jul 17 '13 at 13:50

Oliver Weichhold

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I am putting this code in the View constructor and at that time ViewModel is null as the property hasn't been set yet. And as such I receive NullRef exception – JFoulkes Jul 17 '13 at 14:27
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Then make sure this code is called after the ViewModel is set. – Oliver Weichhold Jul 17 '13 at 14:30

Bind to IReactiveCommand in view code behind

2 Answers2