Add identifier_preparer per-execution context for schema translates

Fixed bug where the "schema_translate_map" feature failed to be taken into
account for the use case of direct execution of
:class:`_schema.DefaultGenerator` objects such as sequences, which included
the case where they were "pre-executed" in order to generate primary key
values when implicit_returning was disabled.

Fixes: #5929
Change-Id: I3fed1d0af28be5ce9c9bb572524dcc8411633f60

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py
index 063f750fa..c80ff3f19 100644
--- a/lib/sqlalchemy/dialects/mysql/base.py
+++ b/lib/sqlalchemy/dialects/mysql/base.py
@@ -988,9 +988,13 @@ from ...types import BLOB
 from ...types import BOOLEAN
 from ...types import DATE
 from ...types import VARBINARY
+from ...util import compat
 from ...util import topological
 
 
+if compat.TYPE_CHECKING:
+    from typing import Any
+
 RESERVED_WORDS = set(
     [
         "accessible",
@@ -1394,7 +1398,7 @@ class MySQLExecutionContext(default.DefaultExecutionContext):
         return self._execute_scalar(
             (
                 "select nextval(%s)"
-                % self.dialect.identifier_preparer.format_sequence(seq)
+                % self.identifier_preparer.format_sequence(seq)
             ),
             type_,
         )
@@ -3263,6 +3267,7 @@ class MySQLDialect(default.DefaultDialect):
         return parser.parse(sql, charset)
 
     def _detect_charset(self, connection):
+        # type: (Any) -> str
         raise NotImplementedError()
 
     def _detect_casing(self, connection):