Can't Write to PostGIS PostGreSQL database via psycopg2

Erik Jones erik at myemma.com
Tue Oct 23 05:43:35 CEST 2007


On Oct 22, 2007, at 8:19 PM, David Michael Schruth, wrote:

> 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®
erik at myemma.com
800.595.4401 or 615.292.5888
615.292.0777 (fax)

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