diff options
Diffstat (limited to 'lib/sqlalchemy/orm/mapper.py')
| -rw-r--r-- | lib/sqlalchemy/orm/mapper.py | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py index 13151f232..a9dad9176 100644 --- a/lib/sqlalchemy/orm/mapper.py +++ b/lib/sqlalchemy/orm/mapper.py @@ -163,11 +163,10 @@ class Mapper(object): self.with_polymorphic = None if isinstance(self.local_table, expression._SelectBaseMixin): - util.warn("mapper %s creating an alias for the given " - "selectable. References to the original selectable " - "may be misinterpreted by queries, polymorphic_on, etc. " - " Consider passing an explicit selectable.alias() construct instead." % self) - self.local_table = self.local_table.alias() + raise sa_exc.InvalidRequestError( + "When mapping against a select() construct, map against an alias() of the construct instead." + "This because several databases don't allow a SELECT from a subquery that does not have an alias." + ) if self.with_polymorphic and isinstance(self.with_polymorphic[1], expression._SelectBaseMixin): self.with_polymorphic = (self.with_polymorphic[0], self.with_polymorphic[1].alias()) |