MQTT Topic Abbreviations

dstrohl · March 19, 2026, 5:15pm

In the docs for MQTT, there’s a section on using abbreviations and base topics.

This says that you can setup a base topic using “~”: “blah/blah”, then add other topics under it using “cmd_t”:“~/set”.

My question is, when setting up a device with multiple components under it, can I (should I?) use a base topic for each component? or is the base topic for the entire payload?

Sir_Goodenough · March 19, 2026, 5:21pm

If you want several entities to appear in the same device, make the device section the same and they show up under the same device.

I would make the base topic the same, but that’s not required AFAIK.

dstrohl · March 19, 2026, 5:24pm

Yup, saw that, but that doesn’t address the question… assuming I am setting up a device with multiple entities using that approach. is the abbreviation field parsed seperately for each entity? or just once for the entire device?

Sir_Goodenough · March 19, 2026, 5:28pm

So if you use the ~ yes it is just that entity I think that’s what I did I believe…

github.com/SirGoodenough/HA_Blueprints

Automations/Octoprint_Additional_Buttons_Helper.yaml

abfe45f22


      
                  qos: "1"
                  retain: false
          default:
          - alias: Home Button Create
            action: mqtt.publish
            data:
              "topic": "{{ h_c_topic }}"
              "retain": true
              "payload": >
                { "~": "{{ printer_topic }}",
                  "avty_t": "{{ avty_t }}",
                  "pl_avail": "{{ pl_avail }}",
                  "pl_not_avail": "{{ pl_not_avail }}",
                  "dev": {
                    "ids": "{{ ids }}",
                    "name": "{{ dv_name }}",
                    "mf": "{{ mf }}",
                    "mdl": "{{ mdl }}",
                    "sa": "{{ sa }}",
                    "sw": "{{ sw }}",
                    "hw": "{{ hw }}",

dstrohl · March 19, 2026, 5:46pm

Thanks, I think that answered it.

IOT7712 · March 21, 2026, 6:41am

I note a number of related posts in various threads.
You’ll be a MQTT expert soon!

Good luck with your project. If you gave a few more clues about your project and kept it in the same thread, you may have got more hints to help you along. Just sayin…