如何在延迟加载的属性上引发 PropertyChanged 事件答案

【问题标题】：How to raise PropertyChanged event on lazy loaded properties如何在延迟加载的属性上引发 PropertyChanged 事件
【发布时间】：2017-09-05 05:41:24
【问题描述】：

所以我在实体和复杂类型之间有一个简单的关系，我想在复杂类型发生变化时通知实体，就像这段代码一样

[Table("Bills")]
public class Bill : NotifyBase
{
    //how to call SetWithNotif when this changes ?
    public virtual Discount Discount { get; set; }

}

[ComplexType]
public class Discount : NotifyBase
{
   //some props in here  
}

 public class NotifyBase : INotifyPropertyChanged,INotifyPropertyChanging
 {       
    public void SetWithNotif<T>(T val,ref T field,[CallerMemberName] string prop = "" )
    {
        if (!field.Equals(val))
        {
            PropertyChanging?.Invoke(this, new PropertyChangingEventArgs(prop));
            field = val;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(prop));
        }
    }
    [field: NotMapped]
    public event PropertyChangedEventHandler PropertyChanged;
    [field: NotMapped]
    public event PropertyChangingEventHandler PropertyChanging;
}

【问题讨论】：

标签： c# wpf entity-framework-6 lazy-loading inotifypropertychanged

【解决方案1】：

哦，我刚刚意识到virtual 意味着它可以有一个body，幸运的是EntityFramework 在它完成延迟加载后调用了那个body，所以这很完美

[Table("Bills")]
public class Bill : NotifyBase
{
    //works !!
    private Discount m_Discount;
    public virtual Discount Discount
    {
        get { return m_Discount; }
        set { SetWithNotif(value, ref m_Discount); }
    }


}

[ComplexType]
public class Discount : NotifyBase
{
   //some props in here  
}

 public class NotifyBase : INotifyPropertyChanged,INotifyPropertyChanging
 {       
    public void SetWithNotif<T>(T val,ref T field,[CallerMemberName] string prop = "" )
    {
        if (!field.Equals(val))
        {
            PropertyChanging?.Invoke(this, new PropertyChangingEventArgs(prop));
            field = val;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(prop));
        }
    }
    [field: NotMapped]
    public event PropertyChangedEventHandler PropertyChanged;
    [field: NotMapped]
    public event PropertyChangingEventHandler PropertyChanging;
}

【讨论】：