- removed ancient assertion that mapped selectables require

"alias names" - the mapper creates its own alias now if
none is present.  Though in this case you need to use
the class, not the mapped selectable, as the source of
column attributes - so a warning is still issued.

1 files changed, 10 insertions, 10 deletions

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index 751ea765d..560c304da 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -135,13 +135,13 @@ class Mapper(object):
                 raise exceptions.ArgumentError("Invalid setting for with_polymorphic")
             else:
                 self.with_polymorphic = None
-
-        check_tables = [self.local_table]
-        if self.with_polymorphic:
-            check_tables.append(self.with_polymorphic[1])
-        for table in check_tables:
-            if table and isinstance(table, expression._SelectBaseMixin):
-                raise exceptions.ArgumentError("Mapping against a Select object requires that it has a name.  Use an alias to give it a name, i.e. s = select(...).alias('myselect')")
+        
+        if isinstance(self.local_table, expression._SelectBaseMixin):
+            util.warn("mapper %s creating an alias for the given selectable - use Class attributes for queries." % self)
+            self.local_table = self.local_table.alias()
+        
+        if self.with_polymorphic and isinstance(self.with_polymorphic[1], expression._SelectBaseMixin):
+            self.with_polymorphic[1] = self.with_polymorphic[1].alias()
 
         # our 'polymorphic identity', a string name that when located in a result set row
         # indicates this Mapper should be used to construct the object instance for that row.
@@ -485,7 +485,7 @@ class Mapper(object):
         self._pks_by_table = {}
         self._cols_by_table = {}
 
-        all_cols = util.Set(chain(*[c2 for c2 in [col.proxy_set for col in [c for c in self._columntoproperty]]]))
+        all_cols = util.Set(chain(*[col.proxy_set for col in self._columntoproperty]))
         pk_cols = util.Set([c for c in all_cols if c.primary_key])
 
         # identify primary key columns which are also mapped by this mapper.
@@ -528,8 +528,8 @@ class Mapper(object):
         by primary key.
         
         """
-        params = dict([(primary_key, sql.bindparam(None, type_=primary_key.type)) for primary_key in self.primary_key])
-        return sql.and_(*[k==v for (k, v) in params.iteritems()]), params
+        params = [(primary_key, sql.bindparam(None, type_=primary_key.type)) for primary_key in self.primary_key]
+        return sql.and_(*[k==v for (k, v) in params]), dict(params)
     _get_clause = property(util.cache_decorator(_get_clause))
     
     def _equivalent_columns(self):