Merge from trunk

[plcapi.git] / trunk / psycopg2 / examples / usercast.py

diff --git a/trunk/psycopg2/examples/usercast.py b/trunk/psycopg2/examples/usercast.py
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+# 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()