mirror of
https://github.com/psycopg/psycopg2.git
synced 2024-11-27 03:13:43 +03:00
e335d6d223
Many editors automatically trim whitespace on save. By trimming all files in one go, makes future diffs cleaner without extraneous whitespace changes.
90 lines
2.8 KiB
Python
90 lines
2.8 KiB
Python
# binary.py - working with binary data
|
|
#
|
|
# Copyright (C) 2001-2010 Federico Di Gregorio <fog@debian.org>
|
|
#
|
|
# psycopg2 is free software: you can redistribute it and/or modify it
|
|
# under the terms of the GNU Lesser General Public License as published
|
|
# by the Free Software Foundation, either version 3 of the License, or
|
|
# (at your option) any later version.
|
|
#
|
|
# psycopg2 is distributed in the hope that it will be useful, but WITHOUT
|
|
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
|
|
# License for more details.
|
|
|
|
## put in DSN your DSN string
|
|
|
|
DSN = 'dbname=test'
|
|
|
|
## don't modify anything below this line (except for experimenting)
|
|
|
|
import sys
|
|
import psycopg2
|
|
|
|
if len(sys.argv) > 1:
|
|
DSN = sys.argv[1]
|
|
|
|
print "Opening connection using dsn:", DSN
|
|
conn = psycopg2.connect(DSN)
|
|
print "Encoding for this connection is", conn.encoding
|
|
|
|
curs = conn.cursor()
|
|
try:
|
|
curs.execute("CREATE TABLE test_binary (id int4, name text, img bytea)")
|
|
except:
|
|
conn.rollback()
|
|
curs.execute("DROP TABLE test_binary")
|
|
curs.execute("CREATE TABLE test_binary (id int4, name text, img bytea)")
|
|
conn.commit()
|
|
|
|
# first we try two inserts, one with an explicit Binary call and the other
|
|
# using a buffer on a file object.
|
|
|
|
data1 = {'id':1, 'name':'somehackers.jpg',
|
|
'img':psycopg2.Binary(open('somehackers.jpg').read())}
|
|
data2 = {'id':2, 'name':'whereareyou.jpg',
|
|
'img':buffer(open('whereareyou.jpg').read())}
|
|
|
|
curs.execute("""INSERT INTO test_binary
|
|
VALUES (%(id)s, %(name)s, %(img)s)""", data1)
|
|
curs.execute("""INSERT INTO test_binary
|
|
VALUES (%(id)s, %(name)s, %(img)s)""", data2)
|
|
|
|
# now we try to extract the images as simple text strings
|
|
|
|
print "Extracting the images as strings..."
|
|
curs.execute("SELECT * FROM test_binary")
|
|
|
|
for row in curs.fetchall():
|
|
name, ext = row[1].split('.')
|
|
new_name = name + '_S.' + ext
|
|
print " writing %s to %s ..." % (name+'.'+ext, new_name),
|
|
open(new_name, 'wb').write(row[2])
|
|
print "done"
|
|
print " python type of image data is", type(row[2])
|
|
|
|
# extract exactly the same data but using a binary cursor
|
|
|
|
print "Extracting the images using a binary cursor:"
|
|
|
|
curs.execute("""DECLARE zot CURSOR FOR
|
|
SELECT img, name FROM test_binary FOR READ ONLY""")
|
|
curs.execute("""FETCH ALL FROM zot""")
|
|
|
|
for row in curs.fetchall():
|
|
name, ext = row[1].split('.')
|
|
new_name = name + '_B.' + ext
|
|
print " writing %s to %s ..." % (name+'.'+ext, new_name),
|
|
open(new_name, 'wb').write(row[0])
|
|
print "done"
|
|
print " python type of image data is", type(row[0])
|
|
|
|
# this rollback is required because we can't drop a table with a binary cursor
|
|
# declared and still open
|
|
conn.rollback()
|
|
|
|
curs.execute("DROP TABLE test_binary")
|
|
conn.commit()
|
|
|
|
print "\nNow try to load the new images, to check it worked!"
|