'got tuple instead' python error when passing a string

Question

Im trying to pass a string varible to an sql query but I get the following error got tuple instead even though I'm passing a string.

& When I use the following command command = ("INSERT INTO dev.roles (name) VALUES ('student')") it works fine... any feedback is appreciated

import psycopg2
import pandas as pd

con=psycopg2.connect(
    dbname= 'xxxxx', 
    host='xxxxxxxxxxxxxxxxxxxx', 
    port= 'xxxx', 
    user= 'xxxxx', 
    password= 'xxxxxxxxx',
)
cur = con.cursor()

mystr="student"
print("Varible Type: ",type(mystr)) # output: Varible Type:  <class 'str'>
command = ("INSERT INTO dev.roles (name) VALUES (%s)",(mystr)) 
cur.execute(command)
con.commit()

cur.close() 
con.close()

This code outputs the following

Varible Type:  <class 'str'>
Traceback (most recent call last):
  File "myFile.py", line 17, in <module>
    cur.execute(command)
TypeError: argument 1 must be a string or unicode object: got tuple instead

command is a tuple, it contains the "INSERT INTO..." string and mystr. — Ahmet
– Ahmet, Commented May 26, 2020 at 18:28

tygzy · Accepted Answer · 2020-05-26 18:42:21Z

1

Your problem is using the % method of formatting in a way that doesn't abide the syntax.

Keep in mind I don't use pandas so I am providing multiples ways to pass in an argument, although I do use SQLite3.

So, how you want to do it:

command = ("INSERT INTO dev.roles (name) VALUES (%s)" % mystr)

The .format method:

command = ("INSERT INTO dev.roles (name) VALUES ({})".format(mystr)

Then there is the concatenation method:

command = "INSERT INTO dev.roles (name) VALUES (" + mystr + ")"

Which is harder and adds unnecessary code.

The reason your code doesn't work is because you are setting the value of command to be a two item tuple, this will only ever work if you pass it in directly to the function where this command takes place, for example in SQLite3 there is an execute function, you would pass in a string that executes something.

There is also the first method but as one single string, instead of a tuple of one string:

command = "INSERT INTO dev.roles (name) VALUES (%s)" % mystr

answered May 26, 2020 at 18:42

tygzy

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1 Comment

CatGirl19 Over a year ago

Thank you, this helped!

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