feat(sqlalchemy-spanner): native UUID data type support in dialect

Adds native Spanner UUID type support to SQLAlchemy dialect:
- Registers "UUID": types.UUID in _type_map for reflection
- Registers types.UUID: "UUID" in _type_map_inv
- Implements visit_UUID and visit_uuid in SpannerTypeCompiler

Author: sakthivelmanii

packages/sqlalchemy-spanner/google/cloud/sqlalchemy_spanner/sqlalchemy_spanner.py

@@ -120,6 +120,7 @@ def process(value):
     "TIMESTAMP": types.TIMESTAMP,
     "ARRAY": types.ARRAY,
     "JSON": types.JSON,
+    "UUID": types.UUID,
 }
 
 
@@ -138,6 +139,8 @@ def process(value):
     types.TIMESTAMP: "TIMESTAMP",
     types.Integer: "INT64",
     types.NullType: "INT64",
+    types.UUID: "UUID",
+    types.Uuid: "UUID",
 }
 
 _compound_keywords = {
@@ -764,6 +767,15 @@ class SpannerTypeCompiler(GenericTypeCompiler):
     Maps SQLAlchemy types to Spanner data types.
     """
 
+    def visit_UUID(self, type_, **kw):
+        return "UUID"
+
+    def visit_uuid(self, type_, **kw):
+        if not type_.native_uuid or not self.dialect.supports_native_uuid:
+            return self.visit_CHAR(types.CHAR(36), **kw)
+        else:
+            return self.visit_UUID(type_, **kw)
+
     def visit_INTEGER(self, type_, **kw):
         return "INT64"
 
@@ -846,6 +858,7 @@ class SpannerDialect(DefaultDialect):
     supports_identity_columns = True
     supports_native_boolean = True
     supports_native_decimal = True
+    supports_native_uuid = True
     supports_statement_cache = True
     # Spanner uses protos for enums. Creating a column like
     # Column("an_enum", Enum("A", "B", "C")) will result in a String

packages/sqlalchemy-spanner/tests/mockserver_tests/test_uuid.py

@@ -0,0 +1,65 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from sqlalchemy import Column, MetaData, Table, types
+from sqlalchemy.schema import CreateTable
+from sqlalchemy.testing import eq_, fixtures
+from google.cloud.sqlalchemy_spanner.sqlalchemy_spanner import (
+    SpannerDialect,
+    _type_map,
+    _type_map_inv,
+)
+
+
+class UuidTest(fixtures.TestBase):
+    def test_uuid_type_mapping(self):
+        """Test UUID is registered in _type_map and _type_map_inv."""
+        assert "UUID" in _type_map
+        eq_(_type_map["UUID"], types.UUID)
+        assert types.UUID in _type_map_inv
+        eq_(_type_map_inv[types.UUID], "UUID")
+        assert types.Uuid in _type_map_inv
+        eq_(_type_map_inv[types.Uuid], "UUID")
+
+    def test_uuid_designate_type(self):
+        """Test reflecting UUID type string returns types.UUID."""
+        dialect = SpannerDialect()
+        assert dialect.supports_native_uuid is True
+        col_type = dialect._designate_type("UUID")
+        eq_(col_type, types.UUID)
+
+    def test_uuid_ddl_compilation_native_enabled(self):
+        """Test DDL compilation for UUID column emits UUID type when native."""
+        dialect = SpannerDialect()
+        metadata = MetaData()
+        table = Table(
+            "test_uuid_table",
+            metadata,
+            Column("user_id", types.Uuid, primary_key=True),
+        )
+        statement = str(CreateTable(table).compile(dialect=dialect)).strip()
+        assert "user_id UUID NOT NULL" in statement
+
+    def test_uuid_ddl_compilation_native_disabled(self):
+        """Test DDL compilation falls back to STRING(36) when native_uuid is False."""
+        dialect = SpannerDialect()
+        dialect.supports_native_uuid = False
+        metadata = MetaData()
+        table = Table(
+            "test_uuid_table",
+            metadata,
+            Column("user_id", types.Uuid, primary_key=True),
+        )
+        statement = str(CreateTable(table).compile(dialect=dialect)).strip()
+        assert "user_id STRING(36) NOT NULL" in statement