ReactiveUI connected Observable CanExecute with IsExecuting properties

Question

If CleanCommand is executing then SearchCommand will be inactive. If SearchCommand is executing then CleanCommand will be inactive.

Barcode is

public long Barcode
{
    get => _barcode;
    set => this.RaiseAndSetIfChanged(ref _barcode, value);
}

private readonly ObservableAsPropertyHelper<bool> _isSearching;
private readonly ObservableAsPropertyHelper<bool> _isCleaning;    
public bool IsSearching => _isSearching.Value;
public bool IsCleaning => _isCleaning.Value;
public ReactiveCommand<Unit, Unit> SearchCommand { get; }
public ReactiveCommand<Unit, Unit> CleanCommand { get; }

In constructor

SearchCommand = ReactiveCommand.CreateFromObservable(Search, SearchCanExecute());
SearchCommand.IsExecuting.ToProperty(this, x => x.IsSearching, out _isSearching);

CleanCommand = ReactiveCommand.CreateFromObservable(Clean, CleanCanExecute());
CleanCommand.IsExecuting.ToProperty(this, x => x.IsCleaning, out _isCleaning);

In class

    IObservable<bool> SearchCanExecute()
    {
        bool isCleaningSuited = !IsCleaning;
        bool isBarcodeSuited = Barcode > 0;

        return Observable.Return(isBarcodeSuited);
    }

    IObservable<bool> CleanCanExecute()
    {
        bool isSearchingSuited = !IsSearching;

        return Observable.Return(isSearchingSuited);
    }

I get the process status with *IsExecuting.ToProperty()

I get values with properties like Barcode.

Should i use WhenAny* method or can i do it this way?

score 1 · Answer 1 · answered Apr 10 '20 at 02:17

I'd probably do this.WhenAnyObservable on the command execution and pipe that into the respective command canExecute. That way you don't really need the functions that return observables and it's a bit more fluid.

Something along the lines of the following

            var commandOneCanExecute = this.WhenAnyObservable(x => x.CommandTwo.IsExecuting).StartWith(false).Select(x => !x);
            var commandTwoCanExecute = this.WhenAnyObservable(x => x.CommandOne.IsExecuting).StartWith(false).Select(x => !x);
            CommandOne = ReactiveCommand.CreateFromObservable(ExecuteCommand, commandOneCanExecute);
            CommandTwo = ReactiveCommand.CreateFromObservable(ExecuteCommand, commandTwoCanExecute);

@echoman Shouldn't this be marked as the answer? ;) – Matthias Jun 16 '20 at 22:48 — Matthias, Jun 16 '20 at 22:48

score 0 · Answer 2 · answered Apr 10 '20 at 07:15

I think i solved the problem.

IObservable<bool> searchCommandObservable = this.WhenAnyObservable(x => x.SearchCommand.IsExecuting).StartWith(false).Select(x => x);
IObservable<bool> cleanCommandObservable = this.WhenAnyObservable(x => x.CleanCommand.IsExecuting).StartWith(false).Select(x => x);
IObservable<bool> barcodeObservable = this.WhenAnyValue(x => x.Barcode).StartWith(0).Select(x => x > 0);

IObservable<bool> searchCanExecute = Observable.Merge(
    searchCommandObservable.Select(x => !x),
    cleanCommandObservable.Select(x => !x),
    barcodeObservable
);

IObservable<bool> cleanCanExecute = Observable.Merge(
    searchCommandObservable.Select(x => !x),
    cleanCommandObservable.Select(x => !x)
);

ReactiveUI connected Observable CanExecute with IsExecuting properties

2 Answers2