我正在尝试下面的代码,它有两个部分,一个是通过棱镜导航。 当允许导航时,我以异步方式开始深度加载,但每次都使用新的上下文。在以后的代码中,我想要取消未完成此加载的待处理导航,但下面的代码甚至不起作用,因此取消是稍后的事情;-)
导航逻辑:这里没问题
public void OnNavigatedTo(NavigationContext navigationContext)
{
int relatieId = (int)navigationContext.Parameters["RelatieId"];
if (_relatie != null && _relatie.RelatieId == relatieId) return;
loadRelatieAsync(relatieId);
}
public void ConfirmNavigationRequest(NavigationContext navigationContext, Action<bool> continuationCallback)
{
bool navigationAllowed = true;
continuationCallback(navigationAllowed);
}
深度加载逻辑:
private async Task loadRelatieAsync(int relatieId)
{
try
{
await Task.Run(async () =>
{
_unitOfWork = _UnitOfWorkFactory.createUnitOfWorkAsync();
IEnumerable<Relatie> relaties = await getRelatieAsync(_unitOfWork, relatieId).ConfigureAwait(true);
_relatieTypeTypes = await getRelatieTypeTypesAsync(_unitOfWork, relatieId).ConfigureAwait(true);
_relatie = relaties.FirstOrDefault();
_unitOfWork.Dispose();
}).ConfigureAwait(true);
processRelatie(_relatie);
processRelatieTypes(_relatie, _relatieTypeTypes);
}
catch (Exception Ex)
{
MessageBox.Show(Ex.Message);
throw;
}
}
private async Task<IEnumerable<Relatie>> getRelatieAsync(IUnitOfWorkAsync unitOfWork, int relatieId)
{
IEnumerable<Relatie> relaties = null;
try
{
IRepositoryAsync<Relatie> relatieRepository = unitOfWork.RepositoryAsync<Relatie>();
relaties = await relatieRepository
.Query(r => r.RelatieId == relatieId)
.Include(i => i.BegrafenisOndernemer)
.SelectAsync()
.ConfigureAwait(false);
IRepositoryAsync<Adres> adresRepository = unitOfWork.RepositoryAsync<Adres>();
//exception is thrown after executing following line
var adressen = await adresRepository
.Query(r => r.RelatieId == relatieId)
.Include(i => i.AdresType)
.SelectAsync()
.ConfigureAwait(false);
_relatieTypeRepository = unitOfWork.RepositoryAsync<RelatieType>();
var relatieTypes = await _relatieTypeRepository
.Query(r => r.RelatieId == relatieId)
.SelectAsync()
.ConfigureAwait(false);
}
catch (Exception Ex)
{
MessageBox.Show(Ex.Message);//exception is shown here
throw;
}
return relaties;
}
private async Task<IEnumerable<RelatieTypeType>> getRelatieTypeTypesAsync(IUnitOfWorkAsync unitOfWork, int relatieId)
{
IEnumerable<RelatieTypeType> relatieTypeTypes = null;
try
{
IRepositoryAsync<RelatieTypeType> relatieTypeTypeRepository =
unitOfWork.RepositoryAsync<RelatieTypeType>();
relatieTypeTypes = await relatieTypeTypeRepository
.Query()
.SelectAsync()
.ConfigureAwait(false);
}
catch (Exception Ex)
{
MessageBox.Show(Ex.Message);
throw;
}
return relatieTypeTypes;
}
我不断得到例外,好像我忘了等待,但事实并非如此。 每当我想在GUI线程上继续时,我也正确使用configureawait(true)。但我一直在深度加载逻辑中得到这个错误。工作单元和存储库类也使用异步等待机制,但我正在等待正确。
在先前的异步操作完成之前,在该上下文上开始第二个操作。使用'await'确保在此上下文上调用另一个方法之前已完成任何异步操作。任何实例成员都不保证是线程安全的。
编辑 (删除了记录器代码以减少代码大小)