Connecting to Postgres Database via Python

Question

I am trying to connect to my database via Python 2.7 with this code:

import csv
import psycopg2
try: 
 conn = psycopg2.connect("dbname='student', user='postgres',password='password', host='localhost'")
 cursor = conn_cursor()
 reader = csv.reader(open('last_file.csv', 'rb'))
 print "connected"
except:
 print "not Connected"

It did work last week and we don't think we've changed anything, but now it won't connect. We've tried using it with the database open and closed, nothing worked. The database does exist in Postgres.

• khelwood: Rather than catching the exception and hiding all information about it, why not let the exception throw so you can see the stack trace?

Answer 1

import psycopg2
try:
 conn = psycopg2.connect("dbname='database_name' user='postgres_user_name' host='localhost' password='user_passwd'")
except:
 print "I am unable to connect to the database"
cur = conn.cursor()
cur.execute("""SELECT * from table_name""")
rows = cur.fetchall()
print "\nShow me the data:\n"
for row in rows:
 print " ", row[0]
 print " ", row[1]

Answer 2

Exception part add like this to see what is error

except Exception as ex:
 print "not Connected"
 print "Error: "+ str(ex)

Answer 3

Try this:

import csv
import psycopg2
try: 
 conn = psycopg2.connect("dbname='student', user='postgres',password='password', host='localhost'")
except:
 print "I am unable to connect to the database."
 cursor = conn.cursor()
try:
 reader = csv.reader(open('last_file.csv', 'rb'))
 print "connected"
except:
 print "not Connected"

Answer 4

Seems like there are something wrong with your postgres.

Try and see postgres log. Location of postgres log by default : tail -f /var/log/postgresql/<>/main/postgresql.log something like this.

Also don't forget to check firewall. Maybe someone disable it by accident.

Answer 5

Also try for pip install PyGreSQL package. Since psycopg2 (some of versions) is under GPL license. It could be tricky for open source license. Just for your information.