订阅自我跟踪实体 PropertyChanged 事件

发布于 2024-12-28 01:54:28 字数 1205 浏览 7 评论 0原文

我正在使用自我跟踪实体编写 WPF 应用程序。当我的模型值发生更改时,我在禁用/启用“保存”按钮时遇到问题。通常,使用常规实体框架模型,我可以简单地订阅 ViewModel 中的 Model.PropertyChanged 事件,然后订阅保存按钮的 RaisePropertyChanged 事件,该事件检查验证并禁用或启用我的保存按钮。

出于某种原因,对于自我跟踪实体,我注意到 Model.PropertyChanged 事件被标记为受保护,因此我无法直接在 ViewModel 中订阅它。有没有办法在不修改T4模板的情况下订阅这个事件?

    protected virtual void OnPropertyChanged(String propertyName)
    {
        if (ChangeTracker.State != ObjectState.Added && ChangeTracker.State != ObjectState.Deleted)
        {
            ChangeTracker.State = ObjectState.Modified;
        }
        if (_propertyChanged != null)
        {
            _propertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    protected virtual void OnNavigationPropertyChanged(String propertyName)
    {
        if (_propertyChanged != null)
        {
            _propertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    event PropertyChangedEventHandler INotifyPropertyChanged.PropertyChanged{ add { _propertyChanged += value; } remove { _propertyChanged -= value; } }
    private event PropertyChangedEventHandler _propertyChanged;
    private ObjectChangeTracker _changeTracker;

I am writing a WPF application using Self-Tracking Entities. I'm having trouble Disabling/Enabling my Save button as my Model's values are changed. Normally with the regular Entity Framework Model I am able to simply subscribe to the Model.PropertyChanged event in my ViewModel, then RaisePropertyChanged for my Save Button, which checks validation and Disabled or Enables my save button.

For some reason, with Self-Tracking Entities I noticed that the Model.PropertyChanged event is marked as protected, so I am unable to subscribe to it directly in my ViewModel. Is there any way to subscribe to this event without modifying the T4 Template??

    protected virtual void OnPropertyChanged(String propertyName)
    {
        if (ChangeTracker.State != ObjectState.Added && ChangeTracker.State != ObjectState.Deleted)
        {
            ChangeTracker.State = ObjectState.Modified;
        }
        if (_propertyChanged != null)
        {
            _propertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    protected virtual void OnNavigationPropertyChanged(String propertyName)
    {
        if (_propertyChanged != null)
        {
            _propertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    event PropertyChangedEventHandler INotifyPropertyChanged.PropertyChanged{ add { _propertyChanged += value; } remove { _propertyChanged -= value; } }
    private event PropertyChangedEventHandler _propertyChanged;
    private ObjectChangeTracker _changeTracker;

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叹倦 2025-01-04 01:54:28

我总是只是修改模板以使其不受保护。它是一个模板是有原因的:)

我想另一种方法是在你的类上创建一个公共方法,该方法在内部引发 PropertyChanged 通知。

partial class MyModel
{
    public RaiseEFPropertyChanged(string propertyName)
    {
        RaisePropertyChanged(propertyName);
    }
}

I've always just modified the template to make it not protected. It's a template for a reason :)

I suppose an alternative would be to create a public method on your class which raises the PropertyChanged notification internally.

partial class MyModel
{
    public RaiseEFPropertyChanged(string propertyName)
    {
        RaisePropertyChanged(propertyName);
    }
}
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