Php mosquitto mqtt client identify client onDisconnect

I am working on PHP project using mosquitto client, I need to check when some user disconnects, and identify the user.

I am using code callback function which only contains the reason for disconnect.

onDisconnect($callback) 

function so that I can handle the disconnect event.

How to link the event to the user in the database.

Thanks,

That callback is saying that your client was disconnected, not some other client (which is what you mean by "user" probably). You can know that another client disconnected only if

• that client has set Last Will topic and disconnected abruptly - this will be published by the broker for you
• that client will publish a specific graceful disconnection topic - you must provide the publishing

In both cases, your client must be subscribed to the topic in question, of course.