Python3: must be real number, not str - Even after float() conversion

Question

I am trying to write some data to a database but I get the error:

must be real number, not str

After a keyboard interrupt (strg + c)

Traceback (most recent call last):
  File "mqtt_logger.py", line 61, in <module>
    time.sleep(1)                # Sleep for a second
KeyboardInterrupt

The function is:

Temperature = BME["Temperature"] #Temperature String from a MQTT Device
Temperature_float = float(Temperature)
print(Temperature_float)
db = initDatabase() #db is a initialised database
cursorObject = db.cursor()
try:
    sqlCommand   = """INSERT INTO tbl_data_jakob (temperature) VALUES (%f)"""
    cursorObject.execute(sqlCommand,Temperature_float)
    db.commit()
    print("Inserted (Hopefully)")
except Exception as e:
    db.rollback()
    print(e)
db.close()

The main Programm is:

ourClient = mqtt.Client("MQTT_Client")        # Create a MQTT client 

object
ourClient.connect("IP", 1883)    # Connect to the test MQTT broker
ourClient.subscribe("tele/Sensor")            # Subscribe to the topic 
db = initDatabase()
ourClient.on_message = messageFunction        # Attach the messageFunction to subscription
ourClient.loop_start()                # Start the MQTT client


# Main program loop
while(1):
    time.sleep(1)                # Sleep for a second

`float(Temperature_float)` ? OR maybe you should use `%s` instead of `%f` ? SQL converts it to string to send it to database - so there is no need to convert string to float. — furas, Apr 01 '20 at 19:14
always put full error message (starting at word "Traceback") in question (not comment) as text (not screenshot). There are other useful information. — furas, Apr 01 '20 at 19:15
You need to remove the `try...except` part to get the full traceback — rdas, Apr 01 '20 at 19:16
When i stop the program it says Traceback (most recent call last): File "mqtt_logger.py", line 61, in time.sleep(1) # Sleep for a second KeyboardInterrupt — jakobheuer, Apr 01 '20 at 19:16
In order to get the full exception, take a look to this: [how to print the full traceback?](https://stackoverflow.com/questions/3702675/how-to-print-the-full-traceback-without-halting-the-program) — EnriqueBet, Apr 01 '20 at 19:17
put error in question, not in comment. More people will see it . — furas, Apr 01 '20 at 19:18
When the try...except block is deleted the program just continuous and ignores the error. @rdas — jakobheuer, Apr 01 '20 at 19:18
The Value of temperature is 21.9 (Read from a MQTT Json message) @ScottHunter — jakobheuer, Apr 01 '20 at 19:22
Everything is in the initial post now @furas Thanks for the ideas for improvements — jakobheuer, Apr 01 '20 at 19:27

score 0 · Accepted Answer · answered Apr 01 '20 at 19:32

0

SOLVED:

Orignial:

sqlCommand   = """INSERT INTO tbl_data_jakob (temperature) VALUES (%f)"""

%f is wrong, you need %s

NEW:

sqlCommand   = """INSERT INTO tbl_data_jakob (temperature) VALUES (%s)"""

Thanks for all the help.

answered Apr 01 '20 at 19:32

jakobheuer

13
1
4

Python3: must be real number, not str - Even after float() conversion

1 Answers1