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fix: Fix android crashing on text binding #2390

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Merged
merged 1 commit into from
Apr 25, 2020
Merged

fix: Fix android crashing on text binding #2390

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17 changes: 10 additions & 7 deletions src/ReactiveUI/Bindings/Property/PropertyBinderImplementation.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -596,30 +596,30 @@ private bool EvalBindingHooks<TViewModel, TView>(TViewModel viewModel, TView vie
signalInitialUpdate.Select(_ => true),
signalObservable);

var changeWithValues = somethingChanged.Select(isVm =>
var changeWithValues = somethingChanged.Select<bool, (bool isValid, object view, bool isViewModel)>(isVm =>
{
if (!Reflection.TryGetValueForPropertyChain(out TVMProp vmValue, view.ViewModel, vmExpression.GetExpressionChain()) ||
!Reflection.TryGetValueForPropertyChain(out TVProp vValue, view, viewExpression.GetExpressionChain()))
{
return null;
return (false, null, false);
}

if (isVm)
{
if (!vmToViewConverter(vmValue, out TVProp vmAsView) || EqualityComparer<TVProp>.Default.Equals(vValue, vmAsView))
{
return null;
return (false, null, false);
}

return Tuple.Create((object)vmAsView, isVm);
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@glennawatson glennawatson Apr 25, 2020

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This is just syntactic sugar to remove a Tuple instance for the more efficient ValueTuple.

return (true, (object)vmAsView, isVm);
}

if (!viewToVmConverter(vValue, out TVMProp vAsViewModel) || EqualityComparer<TVMProp>.Default.Equals(vmValue, vAsViewModel))
{
return null;
return (false, null, false);
}

return Tuple.Create((object)vAsViewModel, isVm);
return (true, (object)vAsViewModel, isVm);
});

var ret = EvalBindingHooks(viewModel, view, vmExpression, viewExpression, BindingDirection.TwoWay);
Expand All @@ -628,7 +628,10 @@ private bool EvalBindingHooks<TViewModel, TView>(TViewModel viewModel, TView vie
return null;
}

IObservable<(object view, bool isViewModel)> changes = changeWithValues.Where(value => value != null).Select(value => (value.Item1, value.Item2)).Publish().RefCount();
IObservable<(object view, bool isViewModel)> changes = changeWithValues
.Where(value => value.isValid)
.Select(value => (value.view, value.isViewModel))
.Publish().RefCount();

IDisposable disposable = changes.Subscribe(isVmWithLatestValue =>
{
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10 changes: 7 additions & 3 deletions src/ReactiveUI/Platforms/android/AndroidObservableForWidgets.cs
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Expand Up @@ -142,10 +142,14 @@ private static DispatchItem CreateFromWidget<TView, TEventArgs>(Expression<Func<
{
var view = (TView)x;

return Observable.FromEvent<EventHandler<TEventArgs>, TEventArgs>(
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@glennawatson glennawatson Apr 25, 2020

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This was the cause of the error. The event handlers weren't being set properly.

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@glennawatson glennawatson Apr 25, 2020

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Essentially, there was a mismatch between the EventHandler and Rx would cause an exception.

Now we are explicitly specifying the event handler method which is more efficient since it avoids reflection anyway.

return Observable.FromEvent<EventHandler<TEventArgs>, ObservedChange<object, object>>(
eventHandler =>
{
void Handler(object sender, TEventArgs e) => eventHandler(new ObservedChange<object, object>(view, ex));
return Handler;
},
h => addHandler(view, h),
h => removeHandler(view, h))
.Select(_ => new ObservedChange<object, object>(view, ex));
h => removeHandler(view, h));
}
};
}
Expand Down