From 60ddd3725600aa121e2e7b4be49dc9bd244ce0c5 Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Fri, 24 Feb 2023 10:58:25 -0500
Subject: locate automap base in hierarchy directly

Fixed issue in automap where calling ``.prepare()`` from one of the mapped
classes would not use the correct base class when automap detected new
tables, instead using the given class, leading to mappers trying to
configure inheritance. While one should normally call ``.prepare()`` from
the base in any case, it shouldn't misbehave that badly when called from a
subclass.

Fixes: #9367
Change-Id: I705d4d939d45af52bc58a74e65994205ab791634
---
 lib/sqlalchemy/ext/automap.py | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

(limited to 'lib/sqlalchemy/ext')

diff --git a/lib/sqlalchemy/ext/automap.py b/lib/sqlalchemy/ext/automap.py
index 030015284..1861791b7 100644
--- a/lib/sqlalchemy/ext/automap.py
+++ b/lib/sqlalchemy/ext/automap.py
@@ -1188,6 +1188,14 @@ class AutomapBase:
          .. versionadded:: 1.4
 
         """
+
+        for mr in cls.__mro__:
+            if "_sa_automapbase_bookkeeping" in mr.__dict__:
+                automap_base = cast("Type[AutomapBase]", mr)
+                break
+        else:
+            assert False, "Can't locate automap base in class hierarchy"
+
         glbls = globals()
         if classname_for_table is None:
             classname_for_table = glbls["classname_for_table"]
@@ -1237,7 +1245,7 @@ class AutomapBase:
             ]
             many_to_many = []
 
-            bookkeeping = cls._sa_automapbase_bookkeeping
+            bookkeeping = automap_base._sa_automapbase_bookkeeping
             metadata_tables = cls.metadata.tables
 
             for table_key in set(metadata_tables).difference(
@@ -1278,7 +1286,7 @@ class AutomapBase:
 
                     mapped_cls = type(
                         newname,
-                        (cls,),
+                        (automap_base,),
                         clsdict,
                     )
                     map_config = _DeferredMapperConfig.config_for_cls(
@@ -1309,7 +1317,7 @@ class AutomapBase:
 
             for map_config in table_to_map_config.values():
                 _relationships_for_fks(
-                    cls,
+                    automap_base,
                     map_config,
                     table_to_map_config,
                     collection_class,
@@ -1320,7 +1328,7 @@ class AutomapBase:
 
             for lcl_m2m, rem_m2m, m2m_const, table in many_to_many:
                 _m2m_relationship(
-                    cls,
+                    automap_base,
                     lcl_m2m,
                     rem_m2m,
                     m2m_const,
@@ -1332,7 +1340,9 @@ class AutomapBase:
                     generate_relationship,
                 )
 
-            for map_config in _DeferredMapperConfig.classes_for_base(cls):
+            for map_config in _DeferredMapperConfig.classes_for_base(
+                automap_base
+            ):
                 map_config.map()
 
     _sa_decl_prepare = True
-- 
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