Caliburn Micro，Wpf 绑定嵌套模型答案

【问题标题】：Caliburn Micro, Wpf binding nested modelCaliburn Micro，Wpf 绑定嵌套模型
【发布时间】：2018-07-06 20:28:00
【问题描述】：

您好，我有一个带有 Caliburn Micro 和 MongoDb 的应用程序 Wpf 我有一个这样的收藏

[Bson IgnoreExtraElements]
public class ResourceCollection : CompanyModel
{
    public ResourceCollection(string Vat) : base(Vat)
    {
    }

    private long _ResourceID;

    public long ResourceID
    {
        get { return _ResourceID; }
        set { _ResourceID = value; }
    }

    private string _Description;

    public string Description
    {
        get { return _Description; }
        set
        {
            _Description = value;
            NotifyOfPropertyChange(() => Description);
        }
    }
}

CompanyModel 继承自 PropertyChangedBase，并且我有一个视图模型：

public class ResourceCreateViewModel : Screen
{
    private IWindowManager _windowManager;
    private readonly AppConnection _appConnection;
    private readonly ResourceRepository _resourceRepository;

    private ResourceCollection _Resource;
    public ResourceCollection Resource
    {
        get
        {
            return _Resource;
        }
        set
        {
            _Resource = value;
            NotifyOfPropertyChange(() => Resource);
            NotifyOfPropertyChange(() => CanSave);
        }
    }
}

这是我的 xaml

  <TextBox Text="{Binding Resource.Description, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Height="20" DockPanel.Dock="Right"></TextBox>

我的问题是，当我更改 texbox 内的值时，我的 viewmodel 类的集合没有触发，我如何将我的类绑定到文本框？

提前谢谢你

【问题讨论】：

标签： c# .net mongodb mvvm caliburn.micro

【解决方案1】：

它不触发它的原因很简单：Resource 对象没有被设置，你只是在它上面设置了一个属性。要解决此问题，您可以创建一个新属性 ResourceDescription 并绑定到该属性：

    public string ResourceDescription
    {
    get
    {
        return _Resource.Description;
    }
            set
            {
                _Resource.Description = value;
                NotifyOfPropertyChange(() => ResourceDescription);
                NotifyOfPropertyChange(() => Resource);
                NotifyOfPropertyChange(() => CanSave);
            }
    }

Xaml：

<TextBox Text="{Binding Resource.Description, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"

但这有其自身的问题，因为视图模型中的更改不再更新您的视图。相反，您可以订阅资源 PropertyChanged 事件：

private ResourceCollection _Resource;
public ResourceCollection Resource
{
    get
    {
        return _Resource;
    }
    set
    {
        if(_Resource != null)
        {
            _Resource.PropertyChanged -= ResourcePropertyChanged;
        }

        _Resource = value;

        if(_Resource != null)
        {
            _Resource.PropertyChanged += ResourcePropertyChanged;
        }

        NotifyOfPropertyChange(() => Resource);
        NotifyOfPropertyChange(() => CanSave);
    }
}

private void ResourcePropertyChanged(object sender, EventArgs e)
{
    //you might be able to do something better than just notify of changes here
    NotifyOfPropertyChange(() => Resource);
    NotifyOfPropertyChange(() => CanSave);
}

这会很快变得复杂，尤其是当您订阅嵌套在对象图中更深的属性时。

【讨论】：