1

我正在尝试使用 ObservableAsPropertyHelper 来设置只读属性，但无论我尝试什么，我似乎都无法让它按预期工作。

我可以将它提炼成一个测试（使用 ReactiveUI 4.3.2.0、Nunit.Framework 和 Should，全部来自 NuGet）

[TestFixture]
public class ObservableAsPropertyHelperTests : ReactiveObject 
{
    private bool _Updated;

    public bool Updated
    {
        get { return _Updated; }
        set { this.RaiseAndSetIfChanged(x => x.Updated, value); }
    }

    [Test]
    public void ShouldSetProperty()
    {
        var input = new Subject<bool>();
        var propertyHelper = input.ToProperty(
                source: this, 
                property: x => x.Updated);//Exception here 

        input.OnNext(true);

        this.Updated.ShouldBeTrue();
    }

但这会导致

System.ArgumentException : Object of type 'ReactiveUI.ObservableAsPropertyHelper`1[System.Boolean]' cannot be converted to type 'System.Boolean'.
   at System.RuntimeType.TryChangeType(Object value, Binder binder, CultureInfo culture, Boolean needsSpecialCast)
   at System.RuntimeType.CheckValue(Object value, Binder binder, CultureInfo culture, BindingFlags invokeAttr)
   at System.Reflection.RtFieldInfo.InternalSetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, CultureInfo culture, Boolean doVisibilityCheck, Boolean doCheckConsistency)
   at System.Reflection.RtFieldInfo.SetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, CultureInfo culture)
   at ReactiveUI.OAPHCreationHelperMixin.ToProperty[TObj,TRet](IObservable`1 This, TObj source, Expression`1 property, TRet initialValue, IScheduler scheduler, Boolean setViaReflection) in y:\Dropbox\ReactiveUI_External\ReactiveUI\ObservableAsPropertyHelper.cs:line 184#0
   at RxUILearning.ObservableAsPropertyHelperTests.ShouldSetProperty() in C:\Dev\RxUILearning\ObservableAsPropertyHelperTests.cs:line 45#1

我可以验证传入的参数

    //   source:
    //     The ReactiveObject that has the property
    //
    //   property:
    //     An Expression representing the property (i.e.  'x => x.SomeProperty'

在查看 GitHub 上的源代码后，我可以通过调用

var propertyHelper = input.ToProperty(source: this, property: x => x.Updated, setViaReflection:false);

我的代码避免了异常，但也没有通过测试。

我怎样才能避免做错了TM？

4

1 回答 1

2

_Updated 实际上应该是 ObservableAspropertyHelper

[TestFixture]
public class ObservableAsPropertyHelperTests : ReactiveObject 
{
    private ObservableAsPropertyHelper<bool> _Updated;

    public bool Updated
    {
        get { return _Updated.Value; }
    }

    [Test]
    public void ShouldSetProperty()
    {
        var input = new Subject<bool>();
        input.ToProperty(
                source: this, 
                property: x => x.Updated);//Now should work

        input.OnNext(true);

        this.Updated.ShouldBeTrue();
    }
于 2013-02-01T15:01:31.070 回答