private ConcurrencyResolutionResult HandleEntryGeneric <TEntity>(PropertyValues originalValues, PropertyValues currentValues, PropertyValues proposedValues)
{
var handlers = _serviceProvider
.GetServices <IConcurrencyErrorHandler <TEntity> >();
ConcurrencyLogMessages.ConcurrencyErrorHandlersExecuting(_logger);
var result = ConcurrencyResolutionResult.Unhandled;
foreach (var handler in handlers)
{
ConcurrencyLogMessages.ConcurrencyErrorHandlerExecuting(_logger, handler);
result = handler.HandleConcurrencyError(originalValues, currentValues, proposedValues);
if (result.IsHandled)
{
ConcurrencyLogMessages.EntityEntryHandledByHandler(_logger, handler);
break;
}
ConcurrencyLogMessages.EntityEntryNotHandledByHandler(_logger, handler);
}
return(result);
}
// For the record, don't even bother trying to Unit Test this. DbUpdateConcurrencyException is not mockable.
// Layers upon layers of non-mockable dependencies, plus polymorphism abuse, just for extra fun
// (E.G. if you try and use an IEntityType that isn't EntityType, you get an exception)
public async Task HandleExceptionAsync(DbUpdateConcurrencyException exception, CancellationToken cancellationToken)
{
ConcurrencyLogMessages.ConcurrencyExceptionHandling(_logger, exception);
foreach (var entry in exception.Entries)
{
ConcurrencyLogMessages.EntityEntryHandling(_logger, entry);
var tEntity = entry.Entity.GetType();
var originalValues = entry.OriginalValues;
var currentValues = await entry.GetDatabaseValuesAsync(cancellationToken);
var proposedValues = entry.CurrentValues;
if (HandleEntry(tEntity, originalValues, currentValues, proposedValues).IsUnhandled)
{
ConcurrencyLogMessages.ConcurrencyExceptionNotHandled(_logger, exception);
throw new InvalidOperationException($"Concurrency exception for entity type {entry.Entity.GetType()} was unhandled", exception);
}
ConcurrencyLogMessages.EntityEntryHandled(_logger);
entry.OriginalValues.SetValues(currentValues);
}
ConcurrencyLogMessages.ConcurrencyExceptionHandled(_logger);
}