Extract table names when comparing to nrte error

Fixed issue where the process of joining two tables could fail if one of
the tables had an unrelated, unresolvable foreign key constraint which
would raise :class:`_exc.NoReferenceError` within the join process, which
nonetheless could be bypassed to allow the join to complete. The logic
which tested the exception for signficance within the process would make
assumptions about the construct which would fail.

Fixes: #5952
Change-Id: I492dacd082ddcf8abb1310ed447a6ed734595bb7

1 files changed, 7 insertions, 2 deletions

diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py
index ee2c4dafc..7c53f437c 100644
--- a/lib/sqlalchemy/sql/selectable.py
+++ b/lib/sqlalchemy/sql/selectable.py
@@ -1229,9 +1229,12 @@ class Join(roles.DMLTableRole, FromClause):
         return bool(constraints)
 
     @classmethod
+    @util.preload_module("sqlalchemy.sql.util")
     def _joincond_scan_left_right(
         cls, a, a_subset, b, consider_as_foreign_keys
     ):
+        sql_util = util.preloaded.sql_util
+
         a = coercions.expect(roles.FromClauseRole, a)
         b = coercions.expect(roles.FromClauseRole, b)
 
@@ -1251,7 +1254,8 @@ class Join(roles.DMLTableRole, FromClause):
                 try:
                     col = fk.get_referent(left)
                 except exc.NoReferenceError as nrte:
-                    if nrte.table_name == left.name:
+                    table_names = {t.name for t in sql_util.find_tables(left)}
+                    if nrte.table_name in table_names:
                         raise
                     else:
                         continue
@@ -1270,7 +1274,8 @@ class Join(roles.DMLTableRole, FromClause):
                     try:
                         col = fk.get_referent(b)
                     except exc.NoReferenceError as nrte:
-                        if nrte.table_name == b.name:
+                        table_names = {t.name for t in sql_util.find_tables(b)}
+                        if nrte.table_name in table_names:
                             raise
                         else:
                             continue