Question

我使用以下代码在我的控制中使用类系统：

public class FlowProWorkingClass:DependencyObject
{
    public TUnitSystemClass ProjectUnitSystem
    {
        get
        {
            return Classes.CurrentFlowProWorkingClass.GeneralOptions.listOfUnitSystems.Find(x => x.Id == Classes.CurrentFlowProWorkingClass.GeneralOptions.DefaultUnitSystemId);
        }
        set
        {
            throw new Exception("Project Unit System can not be setted here!");}
        }
}

我将它绑定到我的控件，如下所示：

<WPFTextBoxUnitConverterControl:TextBoxUnitConvertor
    x:Name="txtGasPhaseFlowCoefficient" UnitSystem="{Binding currentFlowProWorkingClass.ProjectUnitSystem, Mode=OneWay, Source={StaticResource CurrentFlowProWorkingClass}, UpdateSourceTrigger=PropertyChanged}"
    Height="27" Margin="167,245,0,0"  VerticalAlignment="Top" HorizontalAlignment="Left" Width="171"/>

此代码运行良好，目前正在获取单位系统。现在需要控件，当它打开时，我修改了第一个类添加下面的代码来通知更改：

public class FlowProWorkingClass:DependencyObject
{
    [JsonIgnore]
    public static readonly DependencyProperty ProjectUnitSystemProperty =
        DependencyProperty.Register(
            "ProjectUnitSystem",
            typeof(TUnitSystemClass),
            typeof(FlowProWorkingClass),
            new PropertyMetadata(ProjectUnitSystemOnChanged));

    private static void ProjectUnitSystemOnChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
    }

    public TUnitSystemClass ProjectUnitSystem
    {
        get
        {
            SetValue(ProjectUnitSystemProperty, Classes.CurrentFlowProWorkingClass.GeneralOptions.listOfUnitSystems.Find(x => x.Id == Classes.CurrentFlowProWorkingClass.GeneralOptions.DefaultUnitSystemId));
            return (TUnitSystemClass) GetValue(ProjectUnitSystemProperty);
        }
        set
        {
            throw new Exception("Project Unit System can not be setted here!");
        }
    }
}

但是现在，控件根本没有绑定！有什么问题？注意：当我写下面的代码时，绑定被完全忽略！根本没有调用get方法！为什么呢？

public static DependencyProperty ProjectUnitSystemProperty =
    DependencyProperty.Register(
        "ProjectUnitSystem",
        typeof(TUnitSystemClass),
        typeof(FlowProWorkingClass),
        new PropertyMetadata(ProjectUnitSystemOnChanged));

private static void ProjectUnitSystemOnChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
}

public TUnitSystemClass ProjectUnitSystem
{
    get
    {
        SetValue(ProjectUnitSystemProperty, Classes.CurrentFlowProWorkingClass.GeneralOptions.listOfUnitSystems.Find(x => x.Id == Classes.CurrentFlowProWorkingClass.GeneralOptions.DefaultUnitSystemId));
        return (TUnitSystemClass) GetValue(ProjectUnitSystemProperty);
    }
    set
    {
        throw new Exception("Project Unit System can not be setted here!");
    }
}

Answer 1

SetValue设置所谓的依赖项属性的本地值，它替换任何先前分配的（单向）绑定。

所以你的属性getter有效地删除了Binding。不得致电SetValue。

get
{
    SetValue(ProjectUnitSystemProperty, ...); // remove this line
    return (TUnitSystemClass)GetValue(ProjectUnitSystemProperty);
}

任何读/写依赖项属性的CLR包装器必须完全如下所示：

public PropertyType PropertyName
{
    get { return (PropertyType)GetValue(PropertyNameProperty); }
    set { SetValue(PropertyNameProperty, value); 
}

对于只读依赖项属性，请查看MSDN上的Read-Only Dependency Properties文章。

将属性更改为依赖项对象时的绑定错误

1 个答案: