C# EF LoadAsync后刷新视图

C# EF LoadAsync后刷新视图,c#,wpf,entity-framework,observablecollection,icollectionview,C#,Wpf,Entity Framework,Observablecollection,Icollectionview,假设要加载大量数据,我希望UI在加载数据时能够响应。目前唯一有效的代码是以下代码,不断刷新不需要的UI。如何在非UI线程中加载数据并在视图中获得最终更新 private static object sync_lock = new object(); private void Load() { MyEntities db = new MyEntities(); TestEntityViewModel testEntityViewModel = (TestEntityViewMo

假设要加载大量数据,我希望UI在加载数据时能够响应。目前唯一有效的代码是以下代码,不断刷新不需要的UI。如何在非UI线程中加载数据并在视图中获得最终更新

private static object sync_lock = new object();

private void Load()
{
    MyEntities db = new MyEntities();

    TestEntityViewModel testEntityViewModel = (TestEntityViewModel)FindResource("testEntityViewModel");

    testEntityViewModel.Source = db.TestEntities.Local; // Source is ObservableCollection<TestEntity>

    BindingOperations.EnableCollectionSynchronization(testEntityViewModel.Source, sync_lock);

            db.TestEntities.LoadAsync().ContinueWith(new Action<Task>(
                (t) =>
                {
                    this.Dispatcher.Invoke(new Action(() =>
                    {
                        View.MoveCurrentToFirst();

                        CommandManager.InvalidateRequerySuggested();
                    }));
                }));
}
private static object sync_lock=new object();
专用空心荷载()
{
MyEntities db=新的MyEntities();
TestEntityViewModel TestEntityViewModel=(TestEntityViewModel)FindResource(“TestEntityViewModel”);
testEntityViewModel.Source=db.TestEntitys.Local;//源是ObservableCollection
BindingOperations.EnableCollectionSynchronization(testEntityViewModel.Source,同步锁定);
db.TestEntities.LoadAsync().ContinueWith(新操作(
(t) =>
{
this.Dispatcher.Invoke(新操作(()=>
{
View.MoveCurrentToFirst();
CommandManager.InvalidateRequestSuggested();
}));
}));
}

注意:如果我删除对
EnableCollectionSynchronization
的调用,则会加载数据,但
ICollectionView
及其
SourceCollection
只有一项。

您似乎正在使用MVVM。这就是我在我的应用程序中的做法

interface ISomeDataService{
    void GetModelItems(Action<Model[], Exception> callback);
}


class SomeDataServiceImpl:ISomeDataService{
    void GetModelItems(Action<Model[], Exception> callback){
        Task.Factory.StartNew(()=>{
            //get model items from WCF for example than call the callback
            //expected to take a while. 
            //you can also directly access DbContext from here
            //if you like
            callback(res, null);
        });
    }
}
此代码使用延迟加载。当UI控件读取Items属性时,将下载数据。在下载所有数据后,此代码将仅刷新集合一次。请注意,此示例适用于.NET4。如果您使用的是.NET4.5,则可以使用async/await关键字使服务更具可读性。但概念是一样的

class MyDemoVM{
    private Model[] items;
    private readonly ISomeDataService service;
    private readonly IDispatcherService dispService;
    public MyDemoVM(){
        service=new SomeDataServiceImpl();
        dispService=new DispatcherService();
        //i use ctor injection here in order to break the dependency on SomeDataServiceImpl and on DispatcherService.
        //DispatcherService delegates to the App dispatcher in order to run code
        //on the UI thread.
    }
    public Model[] Items{
        get{
            if(items==null)GetItems();
            return items;
        }
        set{
            if(items==value)return;
            items=value;
            NotifyChanged("Items");
        }
    }
    private void GetItems(){
        service.GetModelItems((res,ex)=>{
            //this is on a different thread so you need to synchronize
            dispService.Dispatch(()=>{
                Items=res;
            });
        });
    }
}