Xamarin Forms DataBinding不会更新

Question

我正在与DataBindings作斗争。我有一个带有项目的ListView (正确显示)，我需要能够编辑列表中的项目。

我选择一个项目，它打开一个模式(工作良好)与所选项目的信息(工作良好)。

我有以下对象：

 public class Investigation : IDisposable
 {
     public List<InjuredPerson> InjuredPersonnel { get; set; }
     ...
 }

我的ViewModel是这样的：

public class InvestigateUtilityDamagesViewModel : INotifyPropertyChanged
{
    Investigation investigation;
    private InvestigateDamages damage;

    public event PropertyChangedEventHandler PropertyChanged;

    public InvestigateUtilityDamagesViewModel(InvestigateDamages damage)
    {
        this.damage = damage;
        Investigation = new Investigation();
        Investigation.DamageID = damage.DamageID;
        Investigation.InjuredPersonnel = damage.DamageDetails.InjuredPersonnel;
    }

    public Investigation Investigation
    {
        get { return investigation; }
        set
        {
            if (investigation == value)
            {
                return;
            }
            investigation = value;
            OnPropertyChanged("Investigation");
        }
    }

    void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyName));
        SaveInvestigation();
    }
}

XAML：

 <ListView ItemsSource="{Binding Investigation.InjuredPersonnel, Mode=TwoWay}">
...

更新信息的页面发送如下消息：(工作正常)

MessagingCenter.Send<EditInjuredPerson, InjuredPerson>(this, "InjuredPersonEdited", _injuredPerson);

和接收端(工作正常)

private void SaveInjuredPerson(EditInjuredPerson sender, InjuredPerson InjuredPerson)
    {
        var Injured = this.FindByName<ListView>("listInjuries").SelectedItem as InjuredPerson;
        if (Injured != null)

        {
            Injured.Name = InjuredPerson.Name;
            Injured.Position = InjuredPerson.Position;
            Injured.ContactNumber = InjuredPerson.ContactNumber;
            Injured.Injury = InjuredPerson.Injury;
            Injured.NextOfKinName = InjuredPerson.NextOfKinName;
            Injured.NextOfKinNumber = InjuredPerson.NextOfKinNumber;
        }
    }

Answer 1

InjuredPersonnel列表需要在其上引发OnProprertyChanged事件，而不是调查(或除此之外)。

或者，将List<>转换为ObservableCollection<>。

public List<InjuredPerson> InjuredPersonnel { get; set; }

变成了

public ObservableCollection<InjuredPerson> InjuredPersonnel { get; set; }

Here is a related thread.

public class Investigation : IDisposable, INotifyPropertyChanged
     {
         private List<InjuredPerson> _injuredPersonnel;
         public List<InjuredPerson> InjuredPersonnel  { 
            get {
                return _injuredPersonnel;
            } 
            set
            {
                _injuredPersonnel = value;
                OnPropertyChanged("InjuredPersonnel");
            }
         }
         ...
     }