MassTransit Redis integration - redis

Question

I'm starting to work with Masstransit sagas and I built an example, if I use InMemorySagaRepository everything works fine, but when use Redis repository the Increase message is moved to the Consumer_Error queue in RabbitMq with the error message: 'Value cannot be null. Parameter name: key' and this stack trace:
at System.Collections.Generic.Dictionary`2.FindEntry(TKey key)
at System.Collections.Generic.Dictionary`2.TryGetValue(TKey key, TValue& value)
at Automatonymous.AutomatonymousStateMachine`1.GetState(String name)
at Automatonymous.Accessors.RawStateAccessor`1.Automatonymous.StateAccessor<TInstance>.Get(InstanceContext`1 context)
at Automatonymous.Accessors.InitialIfNullStateAccessor`1.<Automatonymous-StateAccessor<TInstance>-Get>d__3.MoveNext()
at Automatonymous.Pipeline.StateMachineSagaMessageFilter`2.<Send>d__5.MoveNext()
at GreenPipes.Filters.ConcurrencyLimitFilter`1.<Send>d__5.MoveNext()
at MassTransit.RedisIntegration.RedisSagaRepository`1.<SendToInstance>d__7`1.MoveNext()
Here's my code:
public class SagaConsumer : MassTransitStateMachine<Number>
{
public SagaConsumer()
{
State(() => Active);
InstanceState(x => x.Status);
Event(() => Created);
Event(() => Increased);
Initially(
When(Created)
.Then(context =>
{
context.Instance.Name = context.Data.Name;
context.Instance.Value = 0;
})
.ThenAsync(context => Console.Out.WriteLineAsync($"New name:{context.Data.Name}"))
.TransitionTo(Active)
);
During(Active,
When(Increased)
.Then(context =>
{
context.Instance.Value = context.Data.Increase ? context.Instance.Value + 1 : context.Instance.Value - 1;
})
.ThenAsync(context => Console.Out.WriteLineAsync($"{context.Instance.Name} increased to value {context.Instance.Value}"))
);
}
public State Active
{
get; set;
}
public Event<ICreateMessage> Created { get; set; }
public Event<IIncreaseMessage> Increased { get; set; }
}
And the configuration code:
var bus = Bus.Factory.CreateUsingRabbitMq(configurator =>
{
var host = configurator.Host(new Uri("rabbitmq://localhost"), h =>
{
h.Username("guest");
h.Password("guest");
});
var redisManager = new PooledRedisClientManager("localhost");
configurator.ReceiveEndpoint("Consumer", endpoint =>
{
endpoint.StateMachineSaga(new SagaConsumer(),
//new InMemorySagaRepository<Number>(),
new RedisSagaRepository<Number>(redisManager),
c => c.UseConcurrencyLimit(10));
});
});
And Saga class:
public class Number : SagaStateMachineInstance, IHasGuidId, IVersionedSaga, CorrelatedBy<Guid>
{
public Guid CorrelationId
{
get;
set;
}
public string Name { get; set; }
public State Status { get; set; }
public int Value { get; set; }
public int Version { get; set; }
public Guid Id
=> CorrelationId;
}
It seems to be related to the Status property of Number class that is null at some point but I'm not sure why or why it's happening only when using Redis

Answer 1

So you should store the status as either an int or a string - and not the State as you have it now. That will resolve the issue you're seeing.