Python Try: Syntax Error

Question

I'm trying to set up a python program to edit a database from input from my arduino, and the try: command is giving me an error and I'm not sure I understand why

import serial
import MySQLdb

dbConn = MySQLdb.connect("localhost","root","Mecool100","ISEF_DB") or die ("Could not connect to database")
cursor = dbConn.cursor()

device = '/dev/ttyACM0'

try:
    print "Trying...",device
    arduino = serial.Serial(device, 250000)
except:
    print "Failed to connect on",device

try:
    data = arduino.readline() #read data
    pieces = data.split("\t")

try:
    cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = data”)
    dbConn.commit()
    cursor.close()
except MySQLdb.IntegrityError:
    print "Failed to insert data"
finally:
    cursor.close()
except:
    print "Failed to get data"

This code is returning the following error:

  File "test.py", line 21
    try:
      ^
SyntaxError: invalid syntax

Could someone please assist me in finding my error?

Thank you :)

You did not put except clause after our previous line pieces = data.split("\t") — Aida Paul
– Aida Paul, Commented Nov 24, 2015 at 2:23
You can't have a try without an except/else/finally. — BrenBarn
– BrenBarn, Commented Nov 24, 2015 at 2:23

El'endia Starman · Accepted Answer · 2015-11-24 02:34:08Z

2

The others who are saying that you need except blocks after your try are right...but they're missing that you already have them. Really, the problem is that this line

cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = data”)

should be this:

cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = data")

” is in fact not the same character as "; it is codepoint 146 in CP1252 (sometimes incorrectly called ANSI) or codepoint 8221 in Unicode. Do chr("”") to see for yourself.

You also need to indent the third try block, so in the end, your code should look like this:

import serial
import MySQLdb

dbConn = MySQLdb.connect("localhost","root","Mecool100","ISEF_DB") or die ("Could not connect to database")
cursor = dbConn.cursor()

device = '/dev/ttyACM0'

try:
    print "Trying...",device
    arduino = serial.Serial(device, 250000)
except:
    print "Failed to connect on",device

try:
    data = arduino.readline() #read data
    pieces = data.split("\t")

    try:
        cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = data")
        dbConn.commit()
        cursor.close()
    except MySQLdb.IntegrityError:
        print "Failed to insert data"
    finally:
        cursor.close()
except:
    print "Failed to get data"

answered Nov 24, 2015 at 2:34

El'endia Starman

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2 Comments

TigerhawkT3 Over a year ago

The OP has a proper try..except, then a try with no except, then a try with its except..finally accidentally in a string, then a hanging except. So no, they don't already have them, even accounting for the smart quote issue.

El'endia Starman Over a year ago

@TigerhawkT3: I assumed that the third try was supposed to be indented, and when the corresponding except and finally blocks are indented too, the hanging except matches up with the second try. Take a look at the print statements and you'll see that's how it was intended.

wim · Accepted Answer · 2015-11-24 02:23:29Z

1

You need an except and/or finally block for the second try: block. A try without an except or finally does not make sense, so the extra block is compulsory by syntax.

In your third try block, you should move the except ahead of the finally.

Additionally, you have a gnarly quote character on this line:

cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = data”)

Make sure it's a " in your code, not a ”.

answered Nov 24, 2015 at 2:23

wim

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Comments

user2682863 · Accepted Answer · 2015-11-24 02:23:28Z

0

every try statement must have an except clause

try:
    1/0
except ZeroDivisionError:
    print("oops")

answered Nov 24, 2015 at 2:23

user2682863

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1 Comment

wim Over a year ago

On the contrary, you can do a try - finally.

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