Can't Write to PostGIS PostGreSQL database via psycopg2

[David Michael Schruth,]

Hi,

I am sort of in a jam here. I am using the PsycoPG2 library to read
data out of a windows XP based PostGIS / PostGreSQL database but I am
apparently unable to write (update or insert) even though I am able to
read (select)

I am using PsycoPG2 2.0.6 (psycopg2-2.0.6.win32-py2.5-pg8.2.4-
release.exe )
with Python 2.5 (python-2.5.msi)
and PostGres 8.2.5.-1 (postgresql-8.2.5-1.zip)
and PostGIS 8.2 (postgis-pg82-setup-1.3.1-1.exe)

I can use PGadminIII to paste the same SQL queries and execute just
fine, but when I try to execute them via python code like

import psycopg2
conn = psycopg2.connect("dbname='postgis' user='postgres'
host='localhost' password='12345'")
c=conn.cursor()
c.execute("""INSERT INTO thetable (name) VALUES ('asdf');""")
c.execute("""UPDATE thetable SET name = 'somename' WHERE id = 321;""")
print(c.statusmessage)
#returns "INSERT 0 1" and "UPDATE 0" respectively

It gives me very specialized table specific error messages if the
query is wrong, but when it's correct, it does nothing and doesn't
update. The only way I can update is pasting the query into the
PgAdminIII query window.

This is a problem on two separate machines (XP and Windows 2003
server) with all of the above components installed by two different
people.

Any help on this would be greatly appreciated.

Thanks in advance,

Dave

 

[Erik Jones]

Hi,

I am sort of in a jam here. I am using the PsycoPG2 library to read
data out of a windows XP based PostGIS / PostGreSQL database but I am
apparently unable to write (update or insert) even though I am able to
read (select)

I am using PsycoPG2 2.0.6 (psycopg2-2.0.6.win32-py2.5-pg8.2.4-
release.exe )
with Python 2.5 (python-2.5.msi)
and PostGres 8.2.5.-1 (postgresql-8.2.5-1.zip)
and PostGIS 8.2 (postgis-pg82-setup-1.3.1-1.exe)

I can use PGadminIII to paste the same SQL queries and execute just
fine, but when I try to execute them via python code like

import psycopg2
conn = psycopg2.connect("dbname='postgis' user='postgres'
host='localhost' password='12345'")
c=conn.cursor()
c.execute("""INSERT INTO thetable (name) VALUES ('asdf');""")
c.execute("""UPDATE thetable SET name = 'somename' WHERE id = 321;""")
print(c.statusmessage)
#returns "INSERT 0 1" and "UPDATE 0" respectively

It gives me very specialized table specific error messages if the
query is wrong, but when it's correct, it does nothing and doesn't
update. The only way I can update is pasting the query into the
PgAdminIII query window.

This is a problem on two separate machines (XP and Windows 2003
server) with all of the above components installed by two different
people.''

The return value of the insert of 'INSERT 0 1' indicates that one row
was inserted so the insert certainly worked. If you're not seeing
the results when you look at the database after the script has run
it's probably because you need to call conn.commit() after your
execute statements in order to commit your transaction as psycopg
does not, by default, run in "autocommit" mode. The update's return
value of 'UPDATE 0' indicates that the where condition of your update
query did not, in fact, match any existing rows in your table.

Erik Jones

Software Developer | Emma®
(e-mail address removed)
800.595.4401 or 615.292.5888
615.292.0777 (fax)

Emma helps organizations everywhere communicate & market in style.
Visit us online at http://www.myemma.com

 

[David Michael Schruth,]

The return value of the insert of 'INSERT 0 1' indicates that one row
was inserted so the insert certainly worked. If you're not seeing
the results when you look at the database after the script has run
it's probably because you need to call conn.commit() after your
execute statements in order to commit your transaction as psycopg
does not, by default, run in "autocommit" mode. The update's return
value of 'UPDATE 0' indicates that the where condition of your update
query did not, in fact, match any existing rows in your table.

Erik Jones

Software Developer | Emma®
(e-mail address removed)
800.595.4401 or 615.292.5888
615.292.0777 (fax)

Emma helps organizations everywhere communicate & market in style.
Visit us online athttp://www.myemma.com

Thank you so much that fixed the problem!