Fixes for public_factory and mysql/pg dml functions

* ensure that the location indicated by public_factory is
  importable

* adjust all of sqlalchemy.sql.expression locations to be correct

* support the case where a public_factory is against a function
  that has another public_factory already, and already replaced the
  __init__ on the target class

* Use mysql.insert(), postgresql.insert(), don't include .dml in the
  class path.

Change-Id: Iac285289455d8d7102349df3814f7cedc758e639

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/dml.py b/lib/sqlalchemy/dialects/mysql/dml.py
index b43b364fa..531b31bc3 100644
--- a/lib/sqlalchemy/dialects/mysql/dml.py
+++ b/lib/sqlalchemy/dialects/mysql/dml.py
@@ -15,6 +15,9 @@ class Insert(StandardInsert):
 
     Adds methods for MySQL-specific syntaxes such as ON DUPLICATE KEY UPDATE.
 
+    The :class:`~.mysql.Insert` object is created using the
+    :func:`sqlalchemy.dialects.mysql.insert` function.
+
     .. versionadded:: 1.2
 
     """
@@ -105,7 +108,9 @@ class Insert(StandardInsert):
         self._post_values_clause = OnDuplicateClause(inserted_alias, values)
 
 
-insert = public_factory(Insert, ".dialects.mysql.insert")
+insert = public_factory(
+    Insert, ".dialects.mysql.insert", ".dialects.mysql.Insert"
+)
 
 
 class OnDuplicateClause(ClauseElement):