postgresql - python adds "E" to string

Question

This string:

"CREATE USER %s PASSWORD %s", (user, pw)

always gets expanded to:

CREATE USER E'someuser' PASSWORD E'somepassword'

Can anyone tell me why?

Edit: The expanded string above is the string my database gives me back in the error message. I'm using psycopg2 to access my postgres database. The real code looks like this:

conn=psycopg2.connect(user=adminuser, password=adminpass, host=host)
cur = conn.cursor()

#user and pw are simple standard python strings the function gets as parameter
cur.execute("CREATE USER %s PASSWORD %s", (user, pw))
conn.commit()

Answer 1

To pass identifiers to postgresql through psycopg use AsIs from the extensions module

from psycopg2.extensions import AsIs
import psycopg2
connection = psycopg2.connect(database='db', user='user')
cur = connection.cursor()
cur.mogrify(
    'CREATE USER %s PASSWORD %s', (AsIs('someuser'), AsIs('somepassword'))
    )
'CREATE USER someuser PASSWORD somepassword'

That works also for passing conditions to clauses like order by:

cur.mogrify(
    'select * from t order by %s', (AsIs('some_column, another column desc'),)
    )
'select * from t order by some_column, another column desc'