Dead code - isTopicExists

[mjarmoc]

https://github.com/AlariCode/nestjs-rmq/blob/fcee2326e46c00cf5904e72083660e798414981a/lib/rmq.service.ts#L157-L162

I believe this one will never get called. If there is no route, then it won't be registered as a routing key in the exchange. If so, then the message will never reach the queue, thus won't reach the rmq-controller.

[AlariCode]

It will be triggered in case: You publish app with @RMQRoute('myTopic') but after some time decide to refactor your code and changed route to @RMQRoute('myNewTopic'). If any of other microservices will use old route this error will be triggered.

[mjarmoc]

Are you sure :)? If you send('myTopic', payload) I think the myNewTopic microservice will not do anything, and all others microservices will response as previously. @RMQRoute registers topics in the exchange that are used to bind to queues, so I can't imagine a scenario where the route does not exist in the controller, because if there is no route, then the message will not be delivered to queue, thus not consumed, thus not checked.

Correct me if I am wrong :)

[AlariCode]

When you first connecting with myTopic, lib will do the following:

• Check if exchange exists or create it.
• Check if queue exists or create it.
• ! Bind topic to a queue, so if any message with this topic come to exchange it will redirected to this queue.
• Service starts listening to this queue.

So after service stops, topic will stay bound to queue inside rabbitmq until you unbind it manually or drop RMQ configs. When you start with myNewTopic:

• Exchange will exist
• Queue will exist
• Another binding with new topic to old queue will be created.
• Service starts listening to this queue.

So after that we will have two bindings:

myTopic -> myQueue
myNewTopic -> myQueue

And 1 consumer that only knows how to deal with myNewTopic. But when you send myTopic it will get to the consumer because of bondings. And this code will be triggered)