MQTT Publish Action question

Mycodo
,
1

Hello,
I am attempting to use the MQTT Publish function action and am not getting the expected results.
My goal is to control a tasmota-flashed smartbulb to reflect the status of my system. The bulb receives mqtt topics of cmnd/bulb_BIG/Color1 with a payload of r,g,b (where each is 0-255) to set the color.

My Conditional Function has the following code:
self.run_action(“a4377005”, value={“topic”: “cmnd/bulb_BIG/Color1”, “payload”: “40,50,60”})
where A4377005 is my MQTT Publish action.

When run, I do not see this payload on MQTT, I only see the payload that’s entered in the MQTT Publish Action Payload field.

3

Here is where the payload is obtained from the dict you pass in the function call. Are you familiar with debugging to use this as a starting point to figure out the issue?

4

I’ll try, I’m not extremely familiar with Python but I can bang at it.

I noticed if I set the MQTT Publish action Payload field to empty, then mycodo.log gets the message “Error: Cannot publish to MQTT server without a payload.”, despite being called with a payload value in the code.

I’m probing around that file, I’ve inserted some extra self.logger.error() functions as:

def run_action(self, dict_vars):
   self.logger.error("Yo!")
   msg = "Payload length:"
   msg += len(dict_vars["value"]["payload"])
   self.logger.error(msg)
   msg = "Payload:"
   msg += dict_vars["value"]["payload"]
   self.logger.error(msg)

    try:

but execution seems to stop after the Yo! and nothing further comes out in the log. Same if I use self.payload.

5

You need to include the try/except, otherwise you will not catch any exceptions. The reason you’re not seeing all log lines printed is because you removed them and it’s likely throwing an exception.

Looking closely at the characters you’re using, you are not using quotes (" - QUOTATION MARK (U+22)), but “ (“ - LEFT DOUBLE QUOTATION MARK (U+201C)) and ” (” - RIGHT DOUBLE QUOTATION MARK (U+201D)), which is invalid Python syntax. This is why you should not use a rich text editor (e.g MS Word) when writing code. An IDE or a plain text editor should be used, which will not replace " with some stylized version of quotes.

6

That’s funny because I had copy/pasted the example line of code from the Usage: description of the mqtt publish action, all of it within the browser. pylint can’t catch those errors?

Retyping that line from scratch strictly through the website still fails.

I also rewrote my debugging portion as

    def run_action(self, dict_vars):
        self.logger.error("Yo!")
        try:
            msg = "Payload length:"
            msg += len(dict_vars["value"]["payload"])
            self.logger.error(msg)
            msg = "Payload:"
            msg += self.payload
            self.logger.error(msg)
        except:
            self.logger.error("Bad juju")

and it’s printing out

2025-03-19 15:14:47,777 - ERROR - mycodo.action.mqtt_publish_a4377005 - Yo!
2025-03-19 15:14:47,778 - ERROR - mycodo.action.mqtt_publish_a4377005 - Bad juju
2025-03-19 15:14:47,778 - ERROR - mycodo.action.mqtt_publish_a4377005 -  Error: Cannot publish to MQTT server without a payload.
7

I can’t reproduce your issue. I have both topic and payload passed to the action and the description renders properly in my browser as quotes, not left and right quotation marks.

Screenshot 2025-03-19 at 18-36-56 CMDev - Function - Mycodo 8.16.0
Screenshot 2025-03-19 at 18-36-56 CMDev - Function - Mycodo 8.16.02276×648 58.8 KB

For your debugging lines, you should change the last “error” to “exception” to log the traceback. Also, you should log dict_vars to see what data you’re working with.

8

Just created a new Conditional Function from scratch, still “Cannot pulish to MQTT server without a payload.”

Screenshot_2025-03-19_16-40-02
Screenshot_2025-03-19_16-40-021011×1058 123 KB

trying this:

    def run_action(self, dict_vars):
        try:
            msg = dict_vars["value"]["payload"]
            self.logger.error(msg)
            self.logger.error("ok?")
        except:
            self.logger.error("bad juju")

results in bad juju.

What would be a good way to have dict_vars printed out in the log?

9

You should change the last error to exception to see the traceback:

    def run_action(self, dict_vars):
        self.logger.info(f"T00: {dict_vars}")
        try:
            msg = dict_vars["value"]["payload"]
        except:
            self.logger.exception("T01")

Also, I assume you’re using the latest version of Mycodo, correct?

10

Results in:

2025-03-19 21:40:35,129 - INFO - mycodo.action.mqtt_publish_1ac5f9bc - T00: {'message': 'Executing all actions of Conditional (Conditional, ID c0927c97-8450-4956-9ec4-ae67db18c151).'}
2025-03-19 21:40:35,129 - ERROR - mycodo.action.mqtt_publish_1ac5f9bc - T01
Traceback (most recent call last):
  File "/opt/Mycodo/mycodo/actions/mqtt_publish.py", line 166, in run_action
    msg = dict_vars["value"]["payload"]
KeyError: 'value'
2025-03-19 21:40:35,130 - ERROR - mycodo.action.mqtt_publish_1ac5f9bc -  Error: Cannot publish to MQTT server without a payload.

Yes this is version 8.16.0

11

I just made a major discovery…
So far, I had been triggering this Condition function to run with the ‘Execute All Actions’ button at the top right.
If I activate the Conditional function, it runs fine and I see the payload on mqtt.
So I guess the Execute All Actions button doesn’t actually run the python code?

facepalm

12

No, it will only execute self.run_all_actions().

“Usage: self.run_all_actions() will sequentially execute all the actions below.”

13

I would propose that the ‘Execute All Actions’ button be modified for the Conditional Function since it doesn’t make sense to run all the actions (including those that can be left partially filled out like the MQTT publish action) when the purpose of the Conditional Function is to conditionally decide which actions to run. You might have actions that do opposite things and running them all doesn’t make sense. This button makes sense in other functions when all actions get executed but less so under the Conditional Function.

Have the button be “Execute this Function”?

14

Just because it doesn’t make sense to you to run all actions, doesn’t mean it doesn’t have use cases for others. It was added specifically because I and others had a need to run all actions. Removing it from Conditional Functions, or any Function that has actions, would remove functionality that is critical to testing. Changing the name to “Execute this Function” is not clear. “Execute all Actions” lets the user know that all actions will be executed, and coupled with the description for run_all_actions(), it can be understood what it does. If anything, being renamed to “Run All Actions” would be most appropriate, but this would only be relevant for Conditional Functions.