Much better examples.

3 files changed, 146 insertions, 1 deletions

diff --git a/examples/myfirstrecipe.py b/examples/myfirstrecipe.py
index 0aa1776..a75a192 100644
--- a/examples/myfirstrecipe.py
+++ b/examples/myfirstrecipe.py
@@ -88,7 +88,10 @@ class SQL_IN(object):
     
     def __init__(self, seq):
 	self._seq = seq
-	
+
+    def prepare(self, conn):
+        pass
+
     def getquoted(self):
         # this is the important line: note how every object in the
         # list is adapted and then how getquoted() is called on it
@@ -98,6 +101,7 @@ class SQL_IN(object):
 	return '(' + ', '.join(qobjs) + ')'
 	
     __str__ = getquoted
+
     
 # add our new adapter class to psycopg list of adapters
 register_adapter(tuple, SQL_IN)
diff --git a/examples/usercast.py b/examples/usercast.py
new file mode 100644
index 0000000..f5b569c
--- /dev/null
+++ b/examples/usercast.py
@@ -0,0 +1,123 @@
+# 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, psycopg
+import psycopg.extensions
+import whrandom
+
+if len(sys.argv) > 1:
+    DSN = sys.argv[1]
+
+print "Opening connection using dns:", DSN
+conn = psycopg.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:
+    """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."""
+        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
+
+    __str__ = getquoted
+    
+    def prepare(self, conn):
+        pass
+
+    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 = psycopg.extensions.new_type((boxoid,), "BOX", Rect)
+psycopg.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()
diff --git a/psycopg/microprotocols_proto.c b/psycopg/microprotocols_proto.c
index 9f2d29e..31cd4cd 100644
--- a/psycopg/microprotocols_proto.c
+++ b/psycopg/microprotocols_proto.c
@@ -34,6 +34,22 @@
 
 /** void protocol implementation **/
 
+/* prepare - prepare object for quotation */
+
+#define psyco_isqlquote_prepare_doc \
+"prepare(conn) -> prepare object with connection 'conn'"
+
+static PyObject *
+psyco_isqlquote_prepare(isqlquoteObject *self, PyObject *args)
+{
+    PyObject* conn = NULL;
+   
+    if (!PyArg_ParseTuple(args, "O", &conn)) return NULL;
+    
+    Py_INCREF(Py_None);
+    return Py_None;
+}
+
 /* getquoted - return quoted representation for object */
 
 #define psyco_isqlquote_getquoted_doc \
@@ -90,6 +106,8 @@ static struct PyMethodDef isqlquoteObject_methods[] = {
      METH_VARARGS, psyco_isqlquote_getbinary_doc},
     {"getbuffer", (PyCFunction)psyco_isqlquote_getbuffer,
      METH_VARARGS, psyco_isqlquote_getbuffer_doc},
+    {"prepare", (PyCFunction)psyco_isqlquote_prepare,
+     METH_VARARGS, psyco_isqlquote_prepare_doc},
     {NULL}
 };