Question

我想根据Visbility的选定值设置Expander的{{1}}。 ComboBox已经映射到ComboBox：

中的对象

Model

我在VM中设置了一个以<ComboBox Name="SelectedCar" ItemsSource="{Binding Path=CarCategories}" SelectedValue="{Binding Path=Car.CarCategory, Mode=TwoWay}"/>方式导出的属性：

Visbility

这就是我使用它的方式：

private Visibility _extraCarDetailsVisibility;
public Visibility ExtraCarDetailsVisibility
{
    get
    {
        if (ManagedPortfolioSelected != null)
        {
            var category = Car.CarCategory.ToLower();
            if (category == "porsche")
            {
                _extraCarDetailsVisibility= Visibility.Visible;
            }
        }
        _extraCarDetailsVisibility=  Visibility.Collapsed;
        return _extraCarDetailsVisibility;
    }
    set 
    { 
        _extraCarDetailsVisibility= value;
        NotifyPropertyChanged("ExtraCarDetailsVisibility");
    }
}

然而，这不起作用，因为我认为<Expander Visibility="{Binding Path=ExtraCarDetailsVisibility}">更改事件未订阅（而且似乎我不能真正来自模型）所以CarCategories属性当我改变汽车类别时永远不会被召回......

你会怎么做？谢谢！

Answer 1

那里有几个问题：

虽然我在ICar界面中继承了INotifyPropertyChanged，但我很遗憾在Car对象中实现了 - 因此无法在那里到达PropertyChanged事件。
我必须更新代码才能在每次更改ComboBox Catgory时触发事件。为此，我不得不：

将一些事件挂钩到Car对象的PropertyChanged事件：

    private ICar _carSelected;
    public IPortfolio CarSelected
    {
        get { return _carSelected; }
        set
        {
            if (_carSelected!= value)
            {
                if (_carSelected!= null)
                {
                    _carSelected.PropertyChanged -= OnCarSelectedPropertyChanged;
                }
                _carSelected= value;
                // Also subscribing to any change that happens to the Carselected
                _carSelected.PropertyChanged += OnCarSelectedPropertyChanged;
            }
            // Notifying when the selected portfolio is changed
            NotifyPropertyChanged("CarSelected");
        }
    }

CarSelected属性更改后触发事件：

void OnCarSelectedPropertyChanged(object sender, PropertyChangedEventArgs e)    
{
    if (e.PropertyName == "CarCategory")
    {
        NotifyPropertyChanged("ExtraCarDetailsVisibility");
    }
}

...那将更新我的可见性属性我已经连接到视图：

    private Visibility _extraCarDetailsVisibility;
    public Visibility ExtraCarDetailsVisibility
    {
        get
        {
            _extraCarDetailsVisibility= Visibility.Collapsed;
            if (PendingCarSelected != null)
            {
                var category = CarSelected.CounterpartyCategory.ToLower();
                if (category == "porsche" || category == "porsches")
                {
                    _extraCarDetailsVisibility= Visibility.Visible;
                }
            }
            return _extraCarDetailsVisibility;
        }
        set
        {
            _extraCarDetailsVisibility= value;
            NotifyPropertyChanged("ExtraCarDetailsVisibility");
        }
    }

派生的财产从未被召唤过

1 个答案: