mirror of
https://github.com/psycopg/psycopg2.git
synced 2024-11-23 01:16:34 +03:00
92 lines
2.7 KiB
Python
92 lines
2.7 KiB
Python
# lobject.py - lobject example
|
|
#
|
|
# Copyright (C) 2001-2006 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)
|
|
|
|
# this will create a large object with a new random oid, we'll
|
|
# use it to make some basic tests about read/write and seek.
|
|
lobj = conn.lobject()
|
|
loid = lobj.oid
|
|
print("Created a new large object with oid", loid)
|
|
|
|
print("Manually importing some binary data into the object:")
|
|
data = open("somehackers.jpg").read()
|
|
len = lobj.write(data)
|
|
print(" imported", len, "bytes of data")
|
|
|
|
conn.commit()
|
|
|
|
print("Trying to (re)open large object with oid", loid)
|
|
lobj = conn.lobject(loid)
|
|
print("Manually exporting the data from the lobject:")
|
|
data1 = lobj.read()
|
|
len = lobj.tell()
|
|
lobj.seek(0, 0)
|
|
data2 = lobj.read()
|
|
if data1 != data2:
|
|
print("ERROR: read after seek returned different data")
|
|
open("somehackers_lobject1.jpg", 'wb').write(data1)
|
|
print(" written", len, "bytes of data to somehackers_lobject1.jpg")
|
|
|
|
lobj.unlink()
|
|
print("Large object with oid", loid, "removed")
|
|
|
|
conn.commit()
|
|
|
|
# now we try to use the import and export functions to do the same
|
|
lobj = conn.lobject(0, 'n', 0, "somehackers.jpg")
|
|
loid = lobj.oid
|
|
print("Imported a new large object with oid", loid)
|
|
|
|
conn.commit()
|
|
|
|
print("Trying to (re)open large object with oid", loid)
|
|
lobj = conn.lobject(loid, 'n')
|
|
print("Using export() to export the data from the large object:")
|
|
lobj.export("somehackers_lobject2.jpg")
|
|
print(" exported large object to somehackers_lobject2.jpg")
|
|
|
|
lobj.unlink()
|
|
print("Large object with oid", loid, "removed")
|
|
|
|
conn.commit()
|
|
|
|
# this will create a very large object with a new random oid.
|
|
lobj = conn.lobject()
|
|
loid = lobj.oid
|
|
print("Created a new large object with oid", loid)
|
|
|
|
print("Manually importing a lot of data into the object:")
|
|
data = "data" * 1000000
|
|
len = lobj.write(data)
|
|
print(" imported", len, "bytes of data")
|
|
|
|
conn.rollback()
|
|
|
|
print("\nNow try to load the new images, to check it worked!")
|