public IDisposable OneWayBind <TViewModel, TView, TVMProp, TVProp>(
TViewModel viewModel,
TView view,
Expression <Func <TViewModel, TVMProp> > vmProperty,
Expression <Func <TView, TVProp> > viewProperty,
Func <TVMProp> fallbackValue = null,
object conversionHint = null)
where TViewModel : class
where TView : IViewFor
{
if (viewProperty == null)
{
var viewPropChain = Reflection.getDefaultViewPropChain(view, Reflection.ExpressionToPropertyNames(vmProperty));
var viewType = Reflection.GetTypesForPropChain(typeof(TView), viewPropChain).Last();
var converter = getConverterForTypes(typeof(TVMProp), viewType);
if (converter == null)
{
throw new ArgumentException(String.Format("Can't convert {0} to {1}. To fix this, register a IBindingTypeConverter", typeof(TVMProp), viewType));
}
return(Reflection.ViewModelWhenAnyValue(viewModel, view, vmProperty)
.SelectMany(x => {
object tmp;
if (!converter.TryConvert(x, viewType, conversionHint, out tmp))
{
return Observable.Empty <object>();
}
return Observable.Return(tmp);
})
.Subscribe(x => Reflection.SetValueToPropertyChain(view, viewPropChain, x, false)));
}
else
{
var converter = getConverterForTypes(typeof(TVMProp), typeof(TVProp));
if (converter == null)
{
throw new ArgumentException(String.Format("Can't convert {0} to {1}. To fix this, register a IBindingTypeConverter", typeof(TVMProp), typeof(TVProp)));
}
return(Reflection.ViewModelWhenAnyValue(viewModel, view, vmProperty)
.SelectMany(x => {
object tmp;
if (!converter.TryConvert(x, typeof(TVProp), conversionHint, out tmp))
{
return Observable.Empty <TVProp>();
}
return Observable.Return(tmp == null ? default(TVProp) : (TVProp)tmp);
})
.BindTo(view, viewProperty, () => {
object tmp;
return converter.TryConvert(fallbackValue(), typeof(TVProp), conversionHint, out tmp) ? (TVProp)tmp : default(TVProp);
}));
}
}
public IDisposable AsyncOneWayBind <TViewModel, TView, TProp, TOut>(
TViewModel viewModel,
TView view,
Expression <Func <TViewModel, TProp> > vmProperty,
Expression <Func <TView, TOut> > viewProperty,
Func <TProp, IObservable <TOut> > selector,
Func <TOut> fallbackValue = null)
where TViewModel : class
where TView : IViewFor
{
if (viewProperty == null)
{
var viewPropChain = Reflection.getDefaultViewPropChain(view, Reflection.ExpressionToPropertyNames(vmProperty));
return(Reflection.ViewModelWhenAnyValue(viewModel, view, vmProperty)
.SelectMany(selector)
.Subscribe(x => Reflection.SetValueToPropertyChain(view, viewPropChain, x, false)));
}
return(Reflection.ViewModelWhenAnyValue(viewModel, view, vmProperty)
.SelectMany(selector)
.BindTo(view, viewProperty, fallbackValue));
}
public IDisposable Bind <TViewModel, TView, TVMProp, TVProp, TDontCare>(
TViewModel viewModel,
TView view,
Expression <Func <TViewModel, TVMProp> > vmProperty,
Expression <Func <TView, TVProp> > viewProperty,
IObservable <TDontCare> signalViewUpdate,
object conversionHint)
where TViewModel : class
where TView : IViewFor
{
var signalInitialUpdate = new Subject <bool>();
var vmPropChain = Reflection.ExpressionToPropertyNames(vmProperty);
string[] viewPropChain;
if (viewProperty == null)
{
viewPropChain = Reflection.getDefaultViewPropChain(view, vmPropChain);
}
else
{
viewPropChain = Reflection.ExpressionToPropertyNames(viewProperty);
}
var vmToViewConverter = getConverterForTypes(typeof(TVMProp), typeof(TVProp));
var viewToVMConverter = getConverterForTypes(typeof(TVProp), typeof(TVMProp));
if (vmToViewConverter == null || viewToVMConverter == null)
{
throw new ArgumentException(
String.Format("Can't two-way convert between {0} and {1}. To fix this, register a IBindingTypeConverter", typeof(TVMProp), typeof(TVProp)));
}
var somethingChanged = Observable.Merge(
Reflection.ViewModelWhenAnyValue(viewModel, view, vmProperty).Select(_ => true),
signalInitialUpdate,
signalViewUpdate != null ?
signalViewUpdate.Select(_ => false) :
view.WhenAnyDynamic(viewPropChain, x => (TVProp)x.Value).Select(_ => false));
string vmChangedString = String.Format("Setting {0}.{1} => {2}.{3}: ",
typeof(TViewModel).Name, String.Join(".", vmPropChain),
typeof(TView).Name, String.Join(".", viewPropChain));
string viewChangedString = String.Format("Setting {0}.{1} => {2}.{3}: ",
typeof(TView).Name, String.Join(".", viewPropChain),
typeof(TViewModel).Name, String.Join(".", vmPropChain));
var changeWithValues = somethingChanged.Select(isVm => {
TVMProp vmValue; TVProp vValue;
if (!Reflection.TryGetValueForPropertyChain(out vmValue, view.ViewModel, vmPropChain) ||
!Reflection.TryGetValueForPropertyChain(out vValue, view, viewPropChain))
{
return(null);
}
if (isVm)
{
var vmAsView = (TVProp)vmToViewConverter.Convert(vmValue, typeof(TVProp), conversionHint);
var changed = EqualityComparer <TVProp> .Default.Equals(vValue, vmAsView) != true;
if (!changed)
{
return(null);
}
this.Log().Info(vmChangedString + (vmAsView != null ? vmAsView.ToString() : "(null)"));
return(Tuple.Create((object)vmAsView, isVm));
}
else
{
var vAsViewModel = (TVMProp)viewToVMConverter.Convert(vValue, typeof(TVMProp), conversionHint);
var changed = EqualityComparer <TVMProp> .Default.Equals(vmValue, vAsViewModel) != true;
if (!changed)
{
return(null);
}
this.Log().Info(viewChangedString + (vAsViewModel != null ? vAsViewModel.ToString() : "(null)"));
return(Tuple.Create((object)vAsViewModel, isVm));
}
});
var ret = changeWithValues.Subscribe(isVmWithLatestValue => {
if (isVmWithLatestValue == null)
{
return;
}
if (isVmWithLatestValue.Item2)
{
Reflection.SetValueToPropertyChain(view, viewPropChain, isVmWithLatestValue.Item1, false);
}
else
{
Reflection.SetValueToPropertyChain(view.ViewModel, vmPropChain, isVmWithLatestValue.Item1, false);
}
});
// NB: Even though it's technically a two-way bind, most people
// want the ViewModel to win at first.
signalInitialUpdate.OnNext(true);
return(ret);
}
