Question

The following query takes out the parentheses from a string, i.e. it regex replaces them with nothing. It works as expected when I test it in pgAdimin III (1.12), but when part of a python script using psycopg2, it does not replace the parentheses at all.

 SELECT
    regexp_replace(location.name, '\\(|\\)', '', 'g') AS host
 FROM
    location

I’m running python 2.7.1 with psycopg2 2.3.2 and my OS is SLES 11 SP1.

I expect that a postgres query run in pgAdmin would return the same exact results as one ran with psycopg2, or is that an incorrect assumption? I can provide data if needed, but location.name is a string, e.g.

(goat) 172.10.x.x -> /var/log/messages

EDIT: Python code:

cursor.execute("""
     SELECT
        regexp_replace(location.name, '\\(|\\)', '', 'g') AS host
     FROM
        location
""") 

The parameterized arguments looks like the answer.

Answer 1

Use parametrized arguments:

sql='SELECT regexp_replace(location, %s, %s, %s)  from foo'
cursor.execute(sql,[r'\(|\)','','g'])

For example:

import psycopg2
connection=psycopg2.connect(
    database=config.PGDB,
    host=config.HOST,
    password=config.PASS)
cursor=connection.cursor()
sql='CREATE TABLE foo (location varchar(40))'
cursor.execute(sql)
sql='INSERT INTO foo (location) VALUES (%s)'
cursor.execute(sql,['(goat) 172.10.x.x -> /var/log/messages'])
sql='SELECT * FROM foo'
cursor.execute(sql)
data=cursor.fetchall()
print(data)
# [('(goat) 172.10.x.x -> /var/log/messages',)]

sql='SELECT regexp_replace(location, %s, %s, %s) FROM foo'
cursor.execute(sql,[r'\(|\)','','g'])
data=cursor.fetchall()
print(data)
# [('goat 172.10.x.x -> /var/log/messages',)]