如何使用 INotifyPropertyChanged 更新派生属性

Question

我在 XtratreeList(DevExress) 的 bindingList 中有一些属性，其中子节点需要显示 parentnode'e 属性。我有以下代码。

public abstract class ClassBase : INotifyPropertyChanged
{
    protected static int initialId = 0;

    private int id;
    private int parentID;
    private string productName;
    private string productType;
    private string colorProductType;

    private void RaisePropertyChanged(string propertyName)
    {
        if ( PropertyChanged != null )
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }

    public int ID
    {
        get { return id; }
        set
        {
            if ( id == value )
                return;

            id = value;
            RaisePropertyChanged("ID");
        }
    }

    public int ParentID
    {
        get { return parentID; }
        set
        {
            if ( parentID == value )
                return;

            parentID = value;
            RaisePropertyChanged("ParentID");
        }
    }

    public string ProductName
    {
        get { return productName; }
        set
        {
            if ( productName == value )
                return;

            productName = value;
            RaisePropertyChanged("ProductName");
        }
    }

    public string ProductType
    {
        get { return productType; }
        set
        {
            if ( productType == value )
                return;

            productType = value;
            RaisePropertyChanged("ProductType");
            RaisePropertyChanged("ColorProductType");
        }
    }

    public string ColorProductType
    {
        get { return colorProductType ; }
        set
        {
            if (colorProductType == value)
                return;

            colorProductType = value;
            RaisePropertyChanged("ColorProductType");
        }
    }

    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;

    #endregion
}`

我的要求是在ProductType 属性更改时更改ColorProductType 属性，基本上ProductType 是父节点属性，ColorProductType - 子节点属性。所以在改变父母的财产时，孩子的财产也需要改变。我将这两个属性都绑定到 2 个文本框。所以改变父道具应该改变两个文本框，但反之亦然。父级内的RaisePropertyChanged("ColorProductType"); 不起作用，colorproducttype 为空，这是什么问题？

Answer 1

RaisePropertyChanged 实际上并不更新属性。它只是发出PropertyChanged 事件的信号。某处必须订阅它并相应地更新其他属性。像这样的：

public abstract class ClassBase : INotifyPropertyChanged
{
    private string productType;
    private string colorProductType;

    public ClassBase()
    {
        this.PropertyChanged += HandlePropertyChanged;
    }

    private void HandlePropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if(e.PropertyName == "ProductType")
        {
            // update ColorProductType here
        }
    }

    private void RaisePropertyChanged(string propertyName)
    {
        if ( PropertyChanged != null )
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }

    public string ProductType
    {
        get { return productType; }
        set
        {
            if ( productType == value )
                return;

            productType = value;
            RaisePropertyChanged("ProductType");
        }
    }

    public string ColorProductType
    {
        get { return colorProductType ; }
        set
        {
            if (colorProductType == value)
                return;

            colorProductType = value;
            RaisePropertyChanged("ColorProductType");
        }
    }

    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;

    #endregion
}

当然，这完全是矫枉过正。当ProductType 更新时，您可以更新ColorProductType，并让PropertyChanged 事件和数据绑定处理文本框更新：

public string ProductType
{
    get { return productType; }
    set
    {
        if ( productType == value )
            return;

        productType = value;

        // update ColorProductType here

        RaisePropertyChanged("ProductType");
    }
}