How do I publish a stream of varying data to a MQTT broker, using micropython - mqtt

Question

I'm trying to create a basic weather station using a Raspberry Pi Pico W. I'm using a pimoroni pico explorer board and a BME280 breakout. I have been able to get the pico to publish to a topic and it will send a message when a single button is pressed, but I'm struggling to get it to publish temperature and humidity values rather than just a message.
I think I've worked out where the problem lies, but I don't know enough about micropython to be able to work out how to fix this issue.
I started with this code, to get the message button pressed when I pressed a button connected to the pico.
mqtt_server = 'broker.mqttdashboard.com'
client_id = 'bigles'
topic_pub = b'cherub'
topic_msg = b'Button Pressed'
Then I changed the topic message to be bme280.read as I figured that would give me 3 values and then I can go from there.
My initial thought process was that because the topic_msg is publishing a statment surrounded by '', it's just going to publish exactly whats between those quotes, right? So lets just remove the brackets and have:
topic_msg = bme280.read()
because it need to publish those values. Then I got the error code
Traceback (most recent call last):
File "<stdin>", line 17
SyntaxError: invalid syntax
So I tried topic_msg = (bme280.read()), but got invalid syntax again
Than I tried
temp = bme280.read()
topic_msg = 'temp'
Resulting in the message "temp" appearing in my broker.
I've tried defining temp as a function, only to be told that it has no len(). I tried addign len, using example code from the internet. It didnt work. I am out of ideas, can anyone suggest anything? Any resources, solutions, suggested google gterms ect, like I said, I'm really new to this. Thanks
Full code with my current edits:
import time
from breakout_bme280 import BreakoutBME280
from pimoroni_i2c import PimoroniI2C
from pimoroni import PICO_EXPLORER_I2C_PINS
i2c = PimoroniI2C(**PICO_EXPLORER_I2C_PINS)
bme = BreakoutBME280(i2c, address=0x76)
import network
import time
from umqtt.simple import MQTTClient
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("i can hear what u sayin","12345678")
time.sleep(5)
print(wlan.isconnected())
def temp
temp = bme.read()
mqtt_server = 'broker.hivemq.com'
client_id = 'bigles'
topic_pub = b'Temp'
topic_msg =
def mqtt_connect():
client = MQTTClient(client_id, mqtt_server, keepalive=3600)
client.connect()
print('Connected to %s MQTT Broker'%(mqtt_server))
return client
def reconnect():
print('Failed to connect to the MQTT Broker. Reconnecting...')
time.sleep(5)
machine.reset()
try:
client = mqtt_connect()
except OSError as e:
reconnect()
while True:
if bme.read():
client.publish(topic_pub, topic_msg)
time.sleep(5)
else:
pass

Answer 1

# Following lines are incorrect- incorrect syntax
# def temp
# temp = bme.read()
mqtt_server = 'broker.hivemq.com'
client_id = 'bigles'
topic_pub = b'Temp'
topic_msg = str(bme.read()) # convert received value into string
Also, in your while loop, you publish the same previously recorded value topic_msg and never read into it again.
Also, move out sleep time.sleep(5) outside if, into loop
Also, suggestion to fix wifi part:
wlan.connect('wifi', 'pass')
while not wlan.isconnected():
pass
print("Connected:", wlan.ifconfig())