azrael wrote:
It logical that it would be more efficient and logical to use a object
oriented database, but in this case I ask because of the portable
nature of sqlite.
so, if I get it right, this should be possible [...]
Did you try it? Did it work? If so,it was pure luck. Attached is a
script that shows how to do it right.
-- Gerhard
# This is an example for storing pickleable Python objects in a SQLite
# database
import cPickle as pickle
try:
from pysqlite2 import dbapi2 as sqlite3
except ImportError:
import sqlite3
class Point(object):
def __init__(self, x, y):
self.x, self.y = x, y
def __repr__(self):
return "<Point(%s, %s)>" % (self.x, self.y)
def test():
con = sqlite3.connect(":memory:")
cur = con.cursor()
# Make sure you store your pickled
# cur.execute("create table pickled(id integer primary key, data blob)")
cur.execute("create table pickled(id integer primary key, data blob)")
# Here we force pickle to use the efficient binary protocol
# (protocol=2). This means you absolutely must use an SQLite BLOB field
# and make sure you use sqlite3.Binary() to bind a BLOB parameter.
p1 = Point(3, 4)
cur.execute("insert into pickled(data) values (?)", (sqlite3.Binary(pickle.dumps(p1, protocol=2)),))
# If we use old pickle protocol (protocol=0, which is also the default),
# we get away with sending ASCII bytestrings to SQLite.
p2 = Point(-5, 3.12)
cur.execute("insert into pickled(data) values (?)", (pickle.dumps(p2, protocol=0),))
# Fetch the BLOBs back from SQLite
cur.execute("select data from pickled")
for row in cur:
serialized_point = row[0]
# Deserialize the BLOB to a Python object - # pickle.loads() needs a
# bytestring.
point = pickle.loads(str(serialized_point))
print "got point back from database", point
if __name__ == "__main__":
test()
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