esp-mqtt subscribe and retained messages

[PaulVdBergh]

Please have a look at my question at esp32.com

Thanks,
Paul.

[david-cermak]

Hi Paul,

related to the line if (client->mqtt_state.message_length_read >= client->mqtt_state.message_length):

• it is supposed to process only related part of the data, further data will be processed in the next iteration of publish.
• Some refactoring were made to this part of the code but at this moment it resides on an idf branch, but will be merged to master once IDFv3.2 is released.

Can you please check if your issue persists when switching to the latest IDF? (no need to add esp-mqtt)?

Thank you,
David

[PaulBreugnot]

Hi everybody,

I have the same issue, even with IDFv3.3.
Maybe the difference is that I subscribe calling the esp_mqtt_client_subscribe function individually for each topic, so, as a workaround, what I do is that I use esp_mqtt_client_config_t's user_context with boolean variables, and, basically :

• I subscribe to the first topic.
• I do nothing until the first retained message is received.
• I subscribe to the second topic.
• I receive the second retained message.

It requires more code and I have to handle the case when there is no retained message in the first topic (otherwise, I will never subscribe to the second topic), but at least it works. ;-)

Paul

[david-cermak]

Resolved in these commits:
db64b79
cf5b8ed
d4b6655