Octoprint, MQTT, and JSONPATH

[Darren_Poulson]

So, going slightly mad with this one. Followed the docs and examples and I just can’t see what I’m missing.

Got Octoprint writing to my MQTT service, no problems there. I can see messages popping up.

[23:44:02] pi@openHABianPi:/etc/openhab2/items$ mosquitto_sub -t octoprint/prusaMk3/temperature/tool0
{"_timestamp": 1534718641, "actual": 24.9, "target": 0.0}
{"_timestamp": 1534718646, "actual": 24.6, "target": 0.0}

I’ve got an item line configured as:

Number PrusaMk3_Temperature_Tool0 "Temperature [%.1f °C]" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/temperature/tool0:state:JSONPATH($.actual)]" }

But all I’m getting in the logs is:

2018-08-19 23:41:31.553 [WARN ] [b.core.events.EventPublisherDelegate] - given new state is NULL, couldn't post update for 'PrusaMk3_Temperature_Tool0'
2018-08-19 23:41:36.559 [WARN ] [b.core.events.EventPublisherDelegate] - given new state is NULL, couldn't post update for 'PrusaMk3_Temperature_Tool0'

Not sure what I’m missing, could just be a typo somewhere but I’ve been over it again and again. Any ideas?

[vzorglub (Vincent Regaud)]

I assume that you have other items configured with the mqtt binding and they work correctly.
Do there error messages occur when a message is received. I mean do they occur at the same time as in your test subscription?

[vzorglub (Vincent Regaud)]

I did a quick and dirty test and it works for me:
I used exactly your item definition
and I was sending the Json via node-red through mqtt but that should not make a difference

2018-08-20 01:47:04.209 [vent.ItemStateChangedEvent] - PrusaMk3_Temperature_Tool0 changed from NULL to 24.9
2018-08-20 01:48:18.327 [vent.ItemStateChangedEvent] - PrusaMk3_Temperature_Tool0 changed from 24.9 to 24.6

Maybe a quick clearing of the cache will make it work… Maybe…

Clear the Cache

Often when one encounters a problem with OH, particularly after an update, OH will refuse to run or certain parts of OH stop working. Some reported errors include: 500 or 404 errors when accessing the UIs lots of exceptions from Jetty or other core components in openhab.log OH refuses to start at all The first step in debugging the problem is to clear the tmp and cache. Installed OH If you are running an installed OH (openHABian, installed using apt or yum): openhab-cli stop openhab-cl…

[Darren_Poulson]

Will try the cache clearing in the morning (can’t at the moment, as if I stop openhab then the house alarm complains about it and don’t want to wake the mrs up! )

I do have other stuff using mqtt and thats all working fine. The error messages do coincide with the test subscription.

What version of openhab are you running? I’m on 2.3.0.

Cheers.

[vzorglub (Vincent Regaud)]

I am running snapshot but it shouldn’t matter the mqtt binding and the jsonpath transform are really mature.
Have your tried another jsonpath on the same message?

Number PrusaMk3_Temperature_Tool0 "Temperature [%.1f °C]" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/temperature/tool0:state:JSONPATH($.target)]" }

for example?

Also have you tried to get the whole string to check the received message?

String PrusaMk3_json "Prusa json [%s]" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/temperature/tool0:state:default]" }

[SpaceGlider (David K.)]

Hi,

I’m also working on Octoprint / MQTT / JSONPATH.

Here are a few items I have so far:

String OctoprintConnected    "Connected [%s]"								                    (gOctoprint)    {mqtt="<[mosquitto:octoprint/connected:state:default]"}

Number:Temperature OctoprintPrinterHotEndTemp		"Nozzle temp [%.1f °C]"     <temperature>	(gOctoprint)	{mqtt="<[mosquitto:octoprint/temperature/tool0:state:JSONPATH($.actual)]"}
Number:Temperature OctoprintPrinterHotEndTempTarget	"Nozzle target [%.1f °C]"   <temperature>	(gOctoprint)	{mqtt="<[mosquitto:octoprint/temperature/tool0:state:JSONPATH($.actual)]"}
Number:Temperature OctoprintPrinterBedTemp			"Bed temp [%.1f °C]"        <temperature>	(gOctoprint)	{mqtt="<[mosquitto:octoprint/temperature/bed:state:JSONPATH($.actual)]"}
Number:Temperature OctoprintPrinterBedTempTarget	"Bed target [%.1f °C]"      <temperature>	(gOctoprint)	{mqtt="<[mosquitto:octoprint/temperature/bed:state:JSONPATH($.target)]"}

Number:Dimensionless OctoprintJobProgressCompletion	"Completion [%.0f %%]"		<battery>       (gOctoprint)	{mqtt="<[mosquitto:octoprint/progress/printing:state:JSONPATH($.progress)]"}

Let me know how far you get and we can complete the list!

[Darren_Poulson]

I actually ended up just re-installing openhabian (I was on a very old version and it was all a little broken), and with a fresh install and the same config files it all works. So thanks for trying it out Vincent, seems it was just my screwed up installation.

So far I have added the following:

String PrusaMk3_Connected "Status: %s" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/mqtt:state:default" }

Number PrusaMk3_Temperature_Tool0 "Temperature [%.1f °C]" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/temperature/tool0:state:JSONPATH($.actual)]" }
Number PrusaMk3_Temperature_Tool0_Target "Temperature [%.1f °C]" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/temperature/tool0:state:JSONPATH($.target)]" }
Number PrusaMk3_Temperature_Tool1 "Temperature [%.1f °C]" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/temperature/tool1:state:JSONPATH($.actual)]" }
Number PrusaMk3_Temperature_Tool1_Target "Temperature [%.1f °C]" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/temperature/tool1:state:JSONPATH($.target)]" }
Number PrusaMk3_Temperature_Bed "Temperature [%.1f °C]" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/temperature/bed:state:JSONPATH($.actual)]" }
Number PrusaMk3_Temperature_Bed_Target "Temperature [%.1f °C]" (PrusaMk3) { mqtt="<[mymosquitto:octoprint/prusaMk3/temperature/bed:state:JSONPATH($.target)]" }

Number PrusaMk3_ProgressCompletion "Completion [%.0f %%]" (PrusaMk3) {mqtt="<[mymosquitto:octoprint/prusaMk3/progress/printing:state:JSONPATH($.progress)]"}
Number PrusaMk3_CurrentLayerHeight "Layer Height [%.1f mm]" (PrusaMk3) {mqtt="<[mymosquitto:octoprint/prusaMk3/event/ZChange:state:JSONPATH($.new)]"}

String PrusaMk3_PrintStart "Started: [%s]" (PrusaMk3) {mqtt="<[mymosquitto:octoprint/prusaMk3/event/PrintStarted:state:JSONPATH($.name)]" }
String PrusaMk3_PrintEnd "Finished: [%s]" (PrusaMk3) {mqtt="<[mymosquitto:octoprint/prusaMk3/event/PrintDone:state:JSONPATH($.name)]" }

And have some of it graphing in grafana. I may also put in failed and cancelled printing status, and need to trigger an alert so I can see the format that that produces (doesn’t mention it in the API docs).

Done a quick rule to hopefully broadcast a barking dog to all my google homes. Will find out if it works when my 4.5 day print finishes.

[hakan (Hakan Tandogan)]

@Darren_Poulson

Done a quick rule to hopefully broadcast a barking dog to all my google homes. Will find out if it works when my 4.5 day print finishes.

That’s EEEEEEVIL