Trax .NET
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Reference

Mediator exceptions

Package Trax.MediatorNamespace Trax.Mediator.ExceptionsSource Exceptions/

The exceptions Trax.Mediator throws, all in Trax.Mediator.Exceptions. None of them is a TrainException: Trax.Api's error filter and the scheduler's runner endpoints pass a TrainException's message through as a train author's words, and these are host or caller errors instead.

Signatures

namespace Trax.Mediator.Exceptions;
 
public class TrainNotFoundException : InvalidOperationException
{
    public TrainNotFoundException(string requestedName);
    public string RequestedName { get; }
}
 
public class AmbiguousTrainNameException : InvalidOperationException
{
    public AmbiguousTrainNameException(string requestedName, IReadOnlyList<string> candidateFullNames);
    public string RequestedName { get; }
    public IReadOnlyList<string> CandidateFullNames { get; }
}
 
public class NoTrainForInputException : InvalidOperationException
{
    public NoTrainForInputException(Type inputType, IReadOnlyList<string> scannedAssemblies);
    public Type InputType { get; }
    public IReadOnlyList<string> ScannedAssemblies { get; }
}
 
public class TrainInputValidationException : InvalidOperationException
{
    public TrainInputValidationException(string trainName, int observedBytes, int maxBytes);
    public string TrainName { get; }
    public int ObservedBytes { get; }
    public int MaxBytes { get; }
}
 
public class TrainAuthorizationNotConfiguredException : InvalidOperationException
{
    public TrainAuthorizationNotConfiguredException(string trainName, string message);
    public string TrainName { get; }
}
 
public class QueueHookTimeoutException : InvalidOperationException
{
    public QueueHookTimeoutException(string trainName, TimeSpan limit);
    public string TrainName { get; }
    public TimeSpan Limit { get; }
}
 
public class QueuedWorkCancelledException : InvalidOperationException
{
    public QueuedWorkCancelledException(long workQueueId, string trainName);
    public long WorkQueueId { get; }
    public string TrainName { get; }
}
 
public class DecisionReplayNotSupportedException : NotSupportedException
{
    public DecisionReplayNotSupportedException(Type implementationType);
    public Type ImplementationType { get; }
}

Members

ExceptionThrown byPropertiesMessage
TrainNotFoundExceptionITrainExecutionService, when no registered train has the nameRequestedName: the name as the caller passed itAlways "The requested train was not found."; the name is only in RequestedName, which is caller input
AmbiguousTrainNameExceptionITrainExecutionService, when the name matches more than one train's friendly nameRequestedName; CandidateFullNames: each match's interface FullName, any of which resolvesLists every candidate
NoTrainForInputExceptionITrainBus.RunAsync and InitializeTrain, when no registered train takes the input's typeInputType; ScannedAssemblies: the names of the assemblies the registry scanned, empty when it does not scanNames the input type, the scanned assemblies and ScanAssemblies(...). Meant for the host's log
TrainInputValidationExceptionITrainExecutionService and TrainInputReader, when input JSON is over the size cap, or a queued input's stored form is over its capTrainName; ObservedBytes; MaxBytesAlways "The train input failed validation."
TrainAuthorizationNotConfiguredExceptionITrainExecutionService, for a [TraxAuthorize] train on a host with no ITrainAuthorizationService, outside a trusted scope and without AllowMissingAuthorizationService()TrainNameNames the train and how to fix the host
QueueHookTimeoutExceptionITrainExecutionService.QueueAsync, when an OnQueue hook runs past MaxQueueHookDuration; the enqueue is rolled backTrainName; LimitNames the train and the limit in seconds
QueuedWorkCancelledExceptionITrainExecutionService.QueueAsync, for a train that defers promotion whose staged entry was cancelled while its hook ranWorkQueueId; TrainNameNames the entry and the train, and says the hook's side-effect may already be applied
DecisionReplayNotSupportedExceptionThe default QueueAsync(..., QueueTrainOptions, ...) body, when ReplayDecisionsOf is set on an implementation that does not override itImplementationType: the registered ITrainExecutionServiceNames the implementation

Behavior

Before Trax.Mediator 1.23.3, ITrainBus threw a TrainException with the same message where it now throws NoTrainForInputException. The conditions under which each exception is thrown are on the page of the member that throws it.

Example

public class OrderEndpoint(ITrainExecutionService trains, ILogger<OrderEndpoint> logger)
{
    public async Task<IResult> Run(string trainName, string inputJson, CancellationToken ct)
    {
        try
        {
            var result = await trains.RunAsync(trainName, inputJson, ct);
            return Results.Ok(result.MetadataId);
        }
        catch (TrainNotFoundException ex)
        {
            logger.LogWarning("Unknown train {Name}", ex.RequestedName);
            return Results.NotFound();
        }
        catch (AmbiguousTrainNameException ex)
        {
            logger.LogWarning("Ambiguous train {Name}", ex.RequestedName);
            return Results.BadRequest();
        }
    }
}

See also