--- a/doc/book/en/devrepo/devcore/dbapi.rst	Wed Jul 24 13:59:08 2013 +0200
+++ b/doc/book/en/devrepo/devcore/dbapi.rst	Thu Jul 25 08:52:15 2013 +0200
@@ -29,6 +29,11 @@
 
   Also, a rollback is automatically done if an error occurs during commit.
 
+.. note::
+
+   A :exc:`ValidationError` has a `entity` attribute. In CubicWeb,
+   this atttribute is set to the entity's eid (not a reference to the
+   entity itself).
 
 Executing RQL queries from a view or a hook
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~