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92 lines
2.6 KiB
Python
92 lines
2.6 KiB
Python
# lobject.py - lobject example
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#
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# Copyright (C) 2001-2006 Federico Di Gregorio <fog@debian.org>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by the
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# Free Software Foundation; either version 2, or (at your option) any later
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# version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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# for more details.
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## put in DSN your DSN string
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DSN = 'dbname=test'
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## don't modify anything below this line (except for experimenting)
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import sys
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import psycopg2
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if len(sys.argv) > 1:
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DSN = sys.argv[1]
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print "Opening connection using dsn:", DSN
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conn = psycopg2.connect(DSN)
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print "Encoding for this connection is", conn.encoding
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# this will create a large object with a new random oid, we'll
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# use it to make some basic tests about read/write and seek.
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lobj = conn.lobject()
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loid = lobj.oid
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print "Created a new large object with oid", loid
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print "Manually importing some binary data into the object:"
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data = open("somehackers.jpg").read()
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len = lobj.write(data)
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print " imported", len, "bytes of data"
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conn.commit()
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print "Trying to (re)open large object with oid", loid
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lobj = conn.lobject(loid)
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print "Manually exporting the data from the lobject:"
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data1 = lobj.read()
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len = lobj.tell()
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lobj.seek(0, 0)
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data2 = lobj.read()
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if data1 != data2:
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print "ERROR: read after seek returned different data"
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open("somehackers_lobject1.jpg", 'wb').write(data1)
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print " written", len, "bytes of data to somehackers_lobject1.jpg"
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lobj.unlink()
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print "Large object with oid", loid, "removed"
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conn.commit()
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# now we try to use the import and export functions to do the same
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lobj = conn.lobject(0, 'n', 0, "somehackers.jpg")
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loid = lobj.oid
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print "Imported a new large object with oid", loid
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conn.commit()
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print "Trying to (re)open large object with oid", loid
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lobj = conn.lobject(loid, 'n')
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print "Using export() to export the data from the large object:"
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lobj.export("somehackers_lobject2.jpg")
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print " exported large object to somehackers_lobject2.jpg"
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lobj.unlink()
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print "Large object with oid", loid, "removed"
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conn.commit()
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# this will create a very large object with a new random oid.
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lobj = conn.lobject()
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loid = lobj.oid
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print "Created a new large object with oid", loid
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print "Manually importing a lot of data into the object:"
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data = "data" * 1000000
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len = lobj.write(data)
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print " imported", len, "bytes of data"
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conn.rollback()
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print "\nNow try to load the new images, to check it worked!"
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