Re: psycopg2 adaptation for UUIDs

On Fri, Sep 19, 2008 at 09:27:47PM +0200, Federico Di Gregorio wrote:
> Il giorno mar, 16/09/2008 alle 10.51 +0200, Brian Sutherland ha scritto:
> > Seeing as both PostgreSQL 8.3 and python 2.5 support the UUID data type,
> > I thought it might be a good feature if psycopg2 supported them natively
> > as well. (don't know what project policy is on this)
> > 
> > This is the code I am using to be able to put UUID object into and get
> > them out of PostgreSQL:
> 
> Starting from your code I added UUID support in psycopg2 (pushed to bzr
> trunk right now). Just:
> 
> import psycopg2.extras
> psycopg2.extras.register_uuid()
> 
> Note that register_uuid() takes an optional OID parameter for
> non-standard installations where the OID value of the PosgreSQL uuid
> type is not 2950. register_uuid() will raise an exception if Python uuid
> module is not available.

Thanks a lot!

Er, but also, I found a bug in my code (that ended up in your patch).
Below is a patch showing it and my solution (which is probably not
exactly correct).


=== modified file 'lib/extras.py'
--- lib/extras.py	2008-09-19 19:25:16 +0000
+++ lib/extras.py	2008-09-22 12:12:09 +0000
@@ -306,7 +306,7 @@
         """Create the UUID type and an uuid.UUID adapter."""
         if not oid: oid = 2950
         _ext.UUID = _ext.new_type((oid, ), "UUID",
-                                   lambda data, cursor: uuid.UUID(data))
+                                   lambda data, cursor: data and uuid.UUID(data) or None)
         _ext.register_type(_ext.UUID)
         _ext.register_adapter(uuid.UUID, UUID_adapter)
         return _ext.UUID
@@ -321,4 +321,4 @@
         raise e
 
 
-__all__ = [ k for k in locals().keys() if not k.startswith('_') ]
\ No newline at end of file
+__all__ = [ k for k in locals().keys() if not k.startswith('_') ]

=== modified file 'tests/types_extras.py'
--- tests/types_extras.py	2008-09-19 19:25:16 +0000
+++ tests/types_extras.py	2008-09-22 12:10:53 +0000
@@ -45,6 +45,9 @@
         u = uuid.UUID('9c6d5a77-7256-457e-9461-347b4358e350');
         s = self.execute("SELECT %s AS foo", (u,))
         self.failUnless(u == s)
+        # must survive NULL cast to a uuid
+        s = self.execute("SELECT NULL::uuid AS foo")
+        self.failUnless(s is None)
 
 def test_suite():
     return unittest.TestLoader().loadTestsFromName(__name__)


> 
> federico
> 
> -- 
> Federico Di Gregorio                         http://people.initd.org/fog
> Debian GNU/Linux Developer                                [email protected]
> INIT.D Developer                                           fog-NGVKUo/i/[email protected]
>        Se sai che hai un ***** di file così, lo manovri subito. -- vodka



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-- 
Brian Sutherland