[GitHub] Programmer74 opened a new issue #2007: Implement an easier way to get the topic information from consumed message

[GitBox <gi...@apache.org>]

Programmer74 opened a new issue #2007: Implement an easier way to get the topic information from consumed message
URL: https://github.com/apache/incubator-pulsar/issues/2007
 
 
   ### Improvement request
   I create a consumer, which is subscribed to several topics using ```topicsPattern```:
   ```
   Consumer consumer = client.newConsumer()
               .topicsPattern("persistent://public/default/test[12]")
               .subscriptionName("name")
               .subscribe();
   ```
   After receiving the message, I would like to know the actual topic name which the incoming message is from. In this case, I would like to check if the message was from "test1" or "test2".
   
   #### Expected behavior
   I would just do something like
   ```
   Message msg = consumer.receive();
   System.out.println(msg.getTopicName());
   ````
   #### Actual behavior
   But there is no such method. As I assumed from reading the sources, I have to do something like
   ```
   Message msg = consumer.receive();
   assert msg.getMessageId() instanceof TopicMessageIdImpl;
   TopicMessageIdImpl topicMessageId = (TopicMessageIdImpl)msg.getMessageId();
   System.out.println(topicMessageId.getTopicName());
   ```
   which works, but is not intuitive.
   #### Request
   I suggest implementing an easier way of getting the topic information from the consuming message. It would be better if I could just call the ```msg.getTopicName()```, or ```msg.getMessageId().getTopicName()``` without nasty casting.
   
   Theoretically I could make PR myself with the adjustments I want, but I am not confident about the java library's internals.
   
   #### System configuration
   **Pulsar version**: ```v2.0.1-incubating```, ```v1.22.1-incubating```, possibly others
   

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