将属性“绑定”到某些逻辑

Question

当我看到这个问题的答案时，我很确定我会说“duh”，但我的大脑并没有我现在想要的那么高效，所以我在这里启动了一个异步帮助线程帮助我...

假设以下类：

public class DerivedTicket: Ticket
{
    public ObservableCollection<TicketDetail> TicketDetails { get; set; }
}

public class Ticket
{
    public static readonly DependencyProperty SubTotalProperty = DependencyProperty.Register("SubTotal", typeof(decimal), typeof(TicketsRow));
    public static readonly DependencyProperty TaxProperty = DependencyProperty.Register("Tax", typeof(decimal), typeof(TicketsRow));
    public static readonly DependencyProperty TotalProperty = DependencyProperty.Register("Total", typeof(decimal), typeof(TicketsRow));

    public decimal SubTotal
    {
        get { return (decimal)this.GetValue(SubTotalProperty); }
        set { this.SetValue(SubTotalProperty, value); }
    }

    public decimal Tax
    {
        get { return (decimal)this.GetValue(TaxProperty); }
        set { this.SetValue(TaxProperty, value); }
    }

    public decimal Total
    {
        get { return (decimal)this.GetValue(TotalProperty); }
        set { this.SetValue(TotalProperty, value); }
    }
}


public class TicketDetail
{
    public static readonly DependencyProperty ItemIdProperty = DependencyProperty.Register("ItemId", typeof(int?), typeof(TicketDetailsRow));
    public static readonly DependencyProperty PriceProperty = DependencyProperty.Register("Price", typeof(decimal), typeof(TicketDetailsRow));
    public static readonly DependencyProperty TaxProperty = DependencyProperty.Register("Tax", typeof(decimal?), typeof(TicketDetailsRow));
    public static readonly DependencyProperty DescriptionProperty = DependencyProperty.Register("Description", typeof(string), typeof(TicketDetailsRow));

    public int? ItemId
    {
        get { return (int?)this.GetValue(ItemIdProperty); }
        set { this.SetValue(ItemIdProperty, value); }
    }

    [Field]
    public decimal Price
    {
        get { return (decimal)this.GetValue(PriceProperty); }
        set { this.SetValue(PriceProperty, value); }
    }

    [Field]
    public decimal? Tax
    {
        get { return (decimal?)this.GetValue(TaxProperty); }
        set { this.SetValue(TaxProperty, value); }
    }

    [Field]
    public string Description
    {
        get { return (string)this.GetValue(DescriptionProperty); }
        set { this.SetValue(DescriptionProperty, value); }
    }
}

您将如何使SubTotal 与TicketDetails 的总和保持同步？使用绑定，还是借助INotifyPropertyChanged，或者其他方式？

Answer 1

您可以使用ObservableCollection 的事件NotifyCollectionChanged 来通知票证详细信息的更改，然后重新计算依赖属性SubTotal。