public async Task <TResult> Dispatch <TResult>(IQuery <TResult> query,
CancellationToken cancellationToken = default)
{
if (query == null)
{
throw new ArgumentNullException(nameof(query),
"Query to dispatch can't be null.");
}
if (cancellationToken == null)
{
throw new ArgumentNullException(nameof(cancellationToken),
"Cancellation token can't be null.");
}
QueryDispatchInfo dispatchInfo = _dispatchModule.GetQueryDispatchInfo(query.GetType());
try
{
await InvokeDispatcher(dispatchInfo, query, cancellationToken).ConfigureAwait(false);
}
catch (QueryDispatchException ex)
{
// Log the details of the dispatch exception and rethrow.
_logger.LogErrorDetails(MessagingLogEvents.MessagingException, ex, "Exception dispatching query.");
throw;
}
catch (Exception ex)
{
_logger.LogError(MessagingLogEvents.MessagingException, ex, "Unexpected Exception dispatching query.");
throw;
}
return(query.Result);
}
// Creates an instance of the consumer that will execute the query and calls it between the
// pre and post filters.
private async Task InvokeDispatcher(QueryDispatchInfo dispatcher, IQuery query, CancellationToken cancellationToken)
{
var consumer = (IQueryConsumer)_services.GetRequiredService(dispatcher.ConsumerType);
var configuredFilters = _filterModule.QueryFilterTypes.Select(ft => _services.GetRequiredService(ft))
.Cast <IQueryFilter>()
.ToArray();
LogQueryDispatch(query, consumer);
await ApplyFilters <IPreQueryFilter>(query, configuredFilters, (f, q) => f.OnPreExecute(q));
await dispatcher.Dispatch(query, consumer, cancellationToken);
await ApplyFilters <IPostQueryFilter>(query, configuredFilters, (f, q) => f.OnPostExecute(q));
}
