@app.on_topic decorator not working with special characters (* is the one I came across)

[Daenara]

Good Evening,

while trying to realize a small project I noticed some pretty strange behavior with the on_topic decorator. I need to receive non-hermes mqtt messages and after I tried to figure out what the best way is to do that, I thought I might try it that way first.

Here is what I tried:

@app.on_topic("weather/+/+/temperature_*C")
async def on_temperature_update(data: TopicData, payload: bytes):
    print(payload.decode('UTF-8'))

Does not work (HermesApp: Unexpected topic: weather/inside/wohnzimmer/temperature_*C)

@app.on_topic("weather/+/+/light_Lux")
async def on_temperature_update(data: TopicData, payload: bytes):
    print(payload.decode('UTF-8'))

Works

@app.on_topic("weather/outside/back/temperature_*C")
async def on_temperature_update(data: TopicData, payload: bytes):
    print(payload.decode('UTF-8'))

Works

Since it did work after I changed the temperature topic for the light one, I am pretty sure that it is the * in my topic that is the issue. According to the mqtt standard, only using + or # in a topic is not allowed, all other UTF-8 characters are fair game. Would it be possible to fix this?

I did some testing with escaping the * symbol when the regex is built and that got it to work, but I doubt my simple solution of replacing token + "$"with token.replace("*", "\*") + "$" in line 566 is a good solution. If this character causes problems when not escaped, others might too, so a more general approach of escaping characters might be the better solution for that.

Daenara

[koenvervloesem]

If we're not sure which other characters might cause problems, your solution is fine for me for now. We can deal with other problems later. Can you create a pull request and document the reason for escaping in the code?

[Daenara]

Document in the code or is there somewhere else you want it documented?

[koenvervloesem]

You can document it on line 566.