I'm receiving the weather data from my weather station with a dongle on my raspberry pi, that has internet connection via wifi. Now I want to send this data to a rails api/app to save it there in a database. The rails app runs on another server, so I want to post the data via http.
How can I do this. I can't add the curl dependency to the rtl_433 project (https://github.com/merbanan/rtl_433) to send the data directly to my backend. Am I able to run the rtl_433 for example with a python script like:
rlt_433 -F json and take that output to send it to my backend or how can I realize that?
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2 Answers
You should be able to execute rtl_433 as a subprocess using the subprocess module. Normally you would just use subprocess.run, but since rtl_433 produces output until it is killed, you will need to use subprocess.Popen and parse the output.
Another option is to pipe the output of rtl_433 to your program and using input() or sys.stdin.readline() to read lines. Like rtl_433 -flags | python3 script.py.
4 Comments
st3ffb3
Thx! I checked it out and it works. After this, I create a dict and send the post with requests import and arguments url and json ;)
Leo
Nice! I'm curious, did you go with the subprocess approach or the pipe approach?
st3ffb3
I used pipe: rtl_433 -flags | python3 data_poster.py and there with sys.stdin.readline()
st3ffb3
ok, I have antoher problem and didn't get time for it: I got it to work with
cat text.json | python weather_poster.py, but if I try to run rtl_433 -F json | weather_poster.py I only get a _io.TextIOWrapper object and can't do anything with this... Any solutions? subprocess.Popen(["rtl_433", "-F", "json"], subprocess.PIPE) doesn't work to...I figured it now out, how to get the data from the subprocess and listen to it all the time:
I installed
python 3.8to use thedatetimelibrary correctly. This approach is supported withversion >= python 3.7I created a python script, taht is listening to the output of my
rtl_433command. As you can see I'm using:rtl_433 -f 868.300M -F json.
here is my listener.py:
import subprocess
import json
import datetime
from threading import Thread
def parse(printed_text):
# here you can parse your string input from the subprocess
# sending to api
def sendToApi(text):
parsed_json = parse(text)
result = <send_to_api(parsed_json)> # here your http.post
print(result)
# This method creates a subprocess with subprocess.Popen and takes a List<str> as command
def execute(cmd):
popen = subprocess.Popen(cmd, stdout=subprocess.PIPE, bufsize=1, universal_newlines=True)
for stdout_line in iter(popen.stdout.readline, ""):
yield stdout_line
popen.stdout.close()
return_code = popen.wait()
if return_code:
raise subprocess.CalledProcessError(return_code, cmd)
for json in execute(['/path/to/rtl_433/build/src/rtl_433', '-f','868.300M', '-F', 'json']):
print(text, end="")
# I'm starting a new thread to avoid data loss. So I can listen to the weather station's output and send it async to the api
thread = Thread(target = sendToApi, args = (text,))
thread.start()
after that I can use:
python3.8 listener.py and get all the data that is sent by the weather station