将 WinForms 控件绑定到 ObjectA.ObjectB.Property

Question

我有一个类代表这样的汽车：

public class Car
{
    public event PropertyChangedEventHandler PropertyChanged;

    private void RaisePropertyChanged([CallerMemberName] string caller = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(caller));
        }
    }

    public enum Colors
    {
        LaserRed,
        GenuineGraniteMica,
        BluePearl,
        SandMicaMetallic,
        NightArmorMetallic
    }

    private string _make;
    public string Make
    {
        get { return _make; }
        set {
                _make = value;
                RaisePropertyChanged();
            }
    }

    private string _model;
    public string Model
    {
        get { return _model; }
        set {
                _model = value;
                RaisePropertyChanged();
            }
    }

    private Colors _color;
    public Colors Color
    {
        get { return _color; }
        set {
                _color = value;
                RaisePropertyChanged();
            }
    }

    public Tire FrontLeftTire = new Tire();
    public Tire FrontRightTire = new Tire();
    public Tire RearLeftTire = new Tire();
    public Tire RearRightTire = new Tire();

    public Car()
    {
        // initialization code
    }

如您所见，我的 Car 类有四个轮胎，Tire 类如下所示：

public class Tire : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private void RaisePropertyChanged([CallerMemberName] string caller = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(caller));
        }
    }

    public enum SizeValues
    {
        [Description("17 inches")]
        SeventeenInches,
        [Description("18 inches")]
        EighteenInches,
        [Description("19 inches")]
        NineteenInches,
        [Description("20 inches")]
        TwentyInches,
    }

    private string _brand;
    public string Brand
    {
        get { return _brand; }
        set
        {
            _brand = value;
            RaisePropertyChanged();
        }
    }

    private SizeValues _size;
    public SizeValues Size
    {
        get { return _size; }
        set
        {
            _size = value;
            RaisePropertyChanged();
        }
    }

    public Tire()
    {
        // initialization code
    }

在我的 WinForms UI 中，我有一个对应于每个轮胎的 Size 属性的组合框（下拉列表）。我正在尝试将每个组合框绑定到相应轮胎的 Size 属性，但我一直用来绑定到汽车对象本身属性的代码不起作用。这是我用来将组合框绑定到汽车的 Color 属性的代码：

comboBoxCarColor.DataBindings.Add(new Binding("SelectedValue", bindingSourceForCars, "Color", true, DataSourceUpdateMode.OnPropertyChanged));
comboBoxCarColor.DataSource = new BindingSource(Utility.ConvertEnumToListOfKeyValuePairs(typeof(Car.Color)), null);
comboBoxCarColor.DisplayMember = "Value";
comboBoxCarColor.ValueMember = "Key";

这很好用。但我认为我现在遇到的问题是我试图绑定到一个属性，该属性不是汽车的直接子属性，而是汽车轮胎之一的属性。所以，这样的事情是行不通的：

comboBoxFrontLeftTimeSize.DataBindings.Add(new Binding("SelectedValue", bindingSourceForCars, "FrontLeftTire.Size", true, DataSourceUpdateMode.OnPropertyChanged));

我认为问题出在数据成员（“FrontLeftTire.Size”）上，但我不确定。我只是以错误的方式引用它还是我在这里的方法完全错误？

Answer 1

我认为有两个问题：

1) 我认为您需要将轮胎对象声明为属性，而不是字段：

而不是这个：

public Tire FrontLeftTire = new Tire()

尝试将其更改为：

private Tire frontLeftTire = new Tire()

public Tire FrontLeftTire {
  get { return frontLeftTire; }
}

2) 我认为您可能遇到了 Microsoft 在 4.0 中针对需要使用 BindingSource 的数据成员所做的重大更改。

而不是这个：

comboBoxFrontLeftTimeSize.DataBindings.Add(
                            new Binding("SelectedValue",
                                        bindingSourceForCars,
                                        "FrontLeftTire.Size",
                                        true,
                                        DataSourceUpdateMode.OnPropertyChanged));

尝试将其更改为：

BindingSource bs = new BindingSource(bindingSourceForCars, null);
comboBoxFrontLeftTimeSize.DataBindings.Add(
                                       "SelectedValue",
                                       bs,
                                       "FrontLeftTire.Size",
                                       true,
                                       DataSourceUpdateMode.OnPropertyChanged));