mirror of
https://github.com/psycopg/psycopg2.git
synced 2024-11-30 12:43:44 +03:00
127 lines
4.3 KiB
Python
127 lines
4.3 KiB
Python
# usercast.py -- example of user defined typecasters
|
|
# -*- encoding: latin-1 -*-
|
|
#
|
|
# Copyright (C) 2001-2005 Federico Di Gregorio <fog@debian.org>
|
|
#
|
|
# This program is free software; you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License as published by the
|
|
# Free Software Foundation; either version 2, or (at your option) any later
|
|
# version.
|
|
#
|
|
# This program is distributed in the hope that it will be useful, but
|
|
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY
|
|
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
# for more details.
|
|
|
|
## put in DSN your DSN string
|
|
|
|
DSN = 'dbname=test'
|
|
|
|
## don't modify anything below tis line (except for experimenting)
|
|
|
|
import sys
|
|
import psycopg2
|
|
import psycopg2.extensions
|
|
import whrandom
|
|
|
|
# importing psycopg.extras will give us a nice tuple adapter: this is wrong
|
|
# because the adapter is meant to be used in SQL IN clauses while we use
|
|
# tuples to represent points but it works and the example is about Rect, not
|
|
# "Point"
|
|
import psycopg2.extras
|
|
|
|
if len(sys.argv) > 1:
|
|
DSN = sys.argv[1]
|
|
|
|
print "Opening connection using dns:", DSN
|
|
conn = psycopg2.connect(DSN)
|
|
print "Initial encoding for this connection is", conn.encoding
|
|
|
|
curs = conn.cursor()
|
|
try:
|
|
curs.execute("CREATE TABLE test_cast (p1 point, p2 point, b box)")
|
|
except:
|
|
conn.rollback()
|
|
curs.execute("DROP TABLE test_cast")
|
|
curs.execute("CREATE TABLE test_cast (p1 point, p2 point, b box)")
|
|
conn.commit()
|
|
|
|
# this is the callable object we use as a typecast (the typecast is
|
|
# usually a function, but we use a class, just to demonstrate the
|
|
# flexibility of the psycopg casting system
|
|
|
|
class Rect(object):
|
|
"""Very simple rectangle.
|
|
|
|
Note that we use this type as a data holder, as an adapter of itself for
|
|
the ISQLQuote protocol used by psycopg's adapt() (see __confrom__ below)
|
|
and eventually as a type-caster for the data extracted from the database
|
|
(that's why __init__ takes the curs argument.)
|
|
"""
|
|
|
|
def __init__(self, s=None, curs=None):
|
|
"""Init the rectangle from the optional string s."""
|
|
self.x = self.y = self.width = self.height = 0.0
|
|
if s: self.from_string(s)
|
|
|
|
def __conform__(self, proto):
|
|
"""This is a terrible hack, just ignore proto and return self."""
|
|
if proto == psycopg2.extensions.ISQLQuote:
|
|
return self
|
|
|
|
def from_points(self, x0, y0, x1, y1):
|
|
"""Init the rectangle from points."""
|
|
if x0 > x1: (x0, x1) = (x1, x0)
|
|
if y0 > y1: (y0, y1) = (y1, y0)
|
|
self.x = x0
|
|
self.y = y0
|
|
self.width = x1 - x0
|
|
self.height = y1 - y0
|
|
|
|
def from_string(self, s):
|
|
"""Init the rectangle from a string."""
|
|
seq = eval(s)
|
|
self.from_points(seq[0][0], seq[0][1], seq[1][0], seq[1][1])
|
|
|
|
def getquoted(self):
|
|
"""Format self as a string usable by the db to represent a box."""
|
|
s = "'((%d,%d),(%d,%d))'" % (
|
|
self.x, self.y, self.x + self.width, self.y + self.height)
|
|
return s
|
|
|
|
def show(self):
|
|
"""Format a description of the box."""
|
|
s = "X: %d\tY: %d\tWidth: %d\tHeight: %d" % (
|
|
self.x, self.y, self.width, self.height)
|
|
return s
|
|
|
|
# here we select from the empty table, just to grab the description
|
|
curs.execute("SELECT b FROM test_cast WHERE 0=1")
|
|
boxoid = curs.description[0][1]
|
|
print "Oid for the box datatype is", boxoid
|
|
|
|
# and build the user cast object
|
|
BOX = psycopg2.extensions.new_type((boxoid,), "BOX", Rect)
|
|
psycopg2.extensions.register_type(BOX)
|
|
|
|
# now insert 100 random data (2 points and a box in each row)
|
|
for i in range(100):
|
|
p1 = (whrandom.randint(0,100), whrandom.randint(0,100))
|
|
p2 = (whrandom.randint(0,100), whrandom.randint(0,100))
|
|
b = Rect()
|
|
b.from_points(whrandom.randint(0,100), whrandom.randint(0,100),
|
|
whrandom.randint(0,100), whrandom.randint(0,100))
|
|
curs.execute("INSERT INTO test_cast VALUES ('%(p1)s', '%(p2)s', %(box)s)",
|
|
{'box':b, 'p1':p1, 'p2':p2})
|
|
print "Added 100 boxed to the database"
|
|
|
|
# select and print all boxes with at least one point inside
|
|
curs.execute("SELECT b FROM test_cast WHERE p1 @ b OR p2 @ b")
|
|
boxes = curs.fetchall()
|
|
print "Found %d boxes with at least a point inside:" % len(boxes)
|
|
for box in boxes:
|
|
print " ", box[0].show()
|
|
|
|
curs.execute("DROP TABLE test_cast")
|
|
conn.commit()
|