[IMP] properly fetch events that have no registration

in order to achieve that, remove the previous patch which was too exclusive (WHERE r.id IS NOT NULL) and use 'virtual' ids instead
the unicity is guaranteed by concatenating the event id and the registration id (if any)

bzr revid: abo@openerp.com-20121011135809-fag9br23hthrwy1s

addons/event/report/report_event_registration.py

@@ -56,10 +56,10 @@ class report_event_registration(osv.osv):
         tools.drop_view_if_exists(cr, 'report_event_registration')
 
         # TOFIX this request won't select events that have no registration
-        cr.execute(""" CREATE OR REPLACE view report_event_registration AS (
+        cr.execute(""" CREATE VIEW report_event_registration AS (
             SELECT
-                event_id,
-                r.id,
+                e.id::char || '/' || coalesce(r.id::char,'') AS id,
+                e.id AS event_id,
                 e.user_id AS user_id,
                 r.user_id AS user_id_registration,
                 r.name AS name_registration,
@@ -79,8 +79,6 @@ class report_event_registration(osv.osv):
                 event_event e
                 LEFT JOIN event_registration r ON (e.id=r.event_id)
 
-            WHERE r.id IS NOT NULL
-
             GROUP BY
                 event_id,
                 user_id_registration,