我正在尝试以下代码,它有两个部分,一个是通过棱镜进行导航。 当允许导航时,我会异步地开始深度加载,但每次都使用新的上下文。在以后的代码中,我想取消未完成此加载的待定导航,但下面的代码甚至不起作用,所以取消暂时是个问题;)
导航逻辑:这里没有问题
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;
}
我一直收到异常,就好像我忘记了使用await一样,但事实并非如此。每当我想要在GUI线程上继续执行时,我也会正确地使用configureawait(true)。但我在deeploading逻辑中不断收到这个错误。UnitOfWork和Repository类也使用async await机制,但在那里我也正确使用了await。
在先前的异步操作完成之前,该上下文上已启动第二个操作。使用'await'确保在调用该上下文上的另一个方法之前完成任何异步操作。任何实例成员都不能保证是线程安全的。
编辑(为减少代码大小已删除记录器代码)
createUnitOfWorkAsync
会创建一个新的上下文,对吗? - Stephen Cleary