From 1e8087790c154abf43da803a235951bd3d1b2d73 Mon Sep 17 00:00:00 2001
From: Glenn Watson <github@glennwatson.net>
Date: Sat, 25 Apr 2020 18:26:05 +1000
Subject: [PATCH] fix: Fix android crashing on text binding

---
 .../Property/PropertyBinderImplementation.cs    | 17 ++++++++++-------
 .../android/AndroidObservableForWidgets.cs      | 10 +++++++---
 2 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/src/ReactiveUI/Bindings/Property/PropertyBinderImplementation.cs b/src/ReactiveUI/Bindings/Property/PropertyBinderImplementation.cs
index 67099bfcf1..4a5ac1e148 100644
--- a/src/ReactiveUI/Bindings/Property/PropertyBinderImplementation.cs
+++ b/src/ReactiveUI/Bindings/Property/PropertyBinderImplementation.cs
@@ -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);
+                    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);
@@ -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 =>
             {
diff --git a/src/ReactiveUI/Platforms/android/AndroidObservableForWidgets.cs b/src/ReactiveUI/Platforms/android/AndroidObservableForWidgets.cs
index 16e59faa33..d0742329ce 100644
--- a/src/ReactiveUI/Platforms/android/AndroidObservableForWidgets.cs
+++ b/src/ReactiveUI/Platforms/android/AndroidObservableForWidgets.cs
@@ -142,10 +142,14 @@ private static DispatchItem CreateFromWidget<TView, TEventArgs>(Expression<Func<
                 {
                     var view = (TView)x;
 
-                    return Observable.FromEvent<EventHandler<TEventArgs>, TEventArgs>(
+                    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));
                 }
             };
         }