PropertyChanged is always null

Question

我正在将一个Datagrid绑定到Observablecollection。下面是我的Observablecollection。但是更改的属性始终为NULL，即使在将XAML设置为这样之后，它也是NULL。请在这个中指导我

谢谢！

<DataGridTextColumn Binding="{Binding, Mode=TwoWay, NotifyOnSourceUpdated=True, NotifyOnTargetUpdated=True, UpdateSourceTrigger=PropertyChanged} Header = "Serial" />

   public class itemobject 
    {
        public event PropertyChangedEventHandler PropertyChanged;
        // This method is called by the Set accessor of each property. 
        // The CallerMemberName attribute that is applied to the optional propertyName 
        // parameter causes the property name of the caller to be substituted as an argument. 
        private void NotifyPropertyChanged( String propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        int sno1;
        public int Sno
        {
            get
            { return sno1; }
            set
            {
                if (value != sno1)
                {
                    sno1= value;
                    NotifyPropertyChanged("Sno");
                }
            }
        }

Answer 1

在XAML中，您应该指定确切更改的属性。

<DataGridTextColumn Binding="{Binding Path = Sno} Header = "Serial" />

和我一样，您需要创建ViewModelBase类。

public abstract class ViewModelBase : INotifyPropertyChanged, IDisposable {
        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged([CallerMemberName]string propertyName = null) {
            var handle = PropertyChanged;
            handle?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
        public virtual void Dispose() => PropertyChanged = null;
    }


 public class itemobject : ViewModelBase{
        int sno1;
        public int Sno{
            get => sno1;
            set{
                if (value != sno1){
                    sno1= value;
                    OnPropertyChanged(nameof(Sno));
                }
            }
        }