Question

在我的模型中，我有一些属性，我想在属性发生变化时执行一些额外的代码。我想将新值和属性名称添加到我的数据库中。我还想保留当前警报列表（值等于true）。

    public Boolean ActionAlarmLowLow
    {
        get
        {
            return _ActionAlarmLowLow;
        }
        set
        {
            if (value != this._ActionAlarmLowLow)
            {
                Boolean oldValue = _ActionAlarmLowLow;
                _ActionAlarmLowLow = value;
                RaisePropertyChanged("ActionAlarmLowLow", oldValue, value, true);
            }
        }
    }

我该怎么做呢？我想知道我是否应该向属性添加两行代码：

DB.Log.addLogItem("ActionAlarmLowLow", value);
AlarmList.UpdateItem("ActionAlarmLowLow", value);

或者，如果我能以某种方式扩展/覆盖RaisePropertyChanged并在其他地方为特定属性做一些额外的事情。我打电话叫

RaisePropertyChangedWriteToDbUpdateAlarmList();`

Answer 1

是的，它非常简单，您只需要使用INotifyPropertyChanged创建一个基类，并在内部调用您想要的任何内容。

public abstract class NotifyPropertyChangedBase: INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged<T>(Expression<Func<T>> expression)
    {
        var memberExpression = (MemberExpression) expression.Body;
        var propertyName = memberExpression.Member.Name;

        var handler = PropertyChanged;
        if (handler != null) 
        {
            // Do your common actions here, before property change notification is fired
            handler(this, new PropertyChangedEventArgs(propertyName));
            // Do your common actions here, after property change notification is fired
        }
    }
}

public class MyClass : NotifyPropertyChangedBase
{
    public Boolean ActionAlarmLowLow
    {
       get
       {
           return _ActionAlarmLowLow;
       }
       set
       {
           if (value != this._ActionAlarmLowLow)
           {
               _ActionAlarmLowLow = value;
               OnPropertyChanged(() => this.ActionAlarmLowLow);
           }
       }
   }
}

重写RaisePropertyChanged以执行其他代码

1 个答案: