Create parameter type aliases for scalar field types. (googleapis#3670)

See googleapis#3364

spanner/google/cloud/spanner/__init__.py

@@ -18,7 +18,6 @@
 import pkg_resources
 __version__ = pkg_resources.get_distribution('google-cloud-spanner').version
 
-
 from google.cloud.spanner.client import Client
 
 from google.cloud.spanner.keyset import KeyRange
@@ -28,6 +27,28 @@
 from google.cloud.spanner.pool import BurstyPool
 from google.cloud.spanner.pool import FixedSizePool
 
-
-__all__ = ['__version__', 'AbstractSessionPool', 'BurstyPool', 'Client',
-           'FixedSizePool', 'KeyRange', 'KeySet']
+from google.cloud.spanner.types import BOOL_PARAM_TYPE
+from google.cloud.spanner.types import BYTES_PARAM_TYPE
+from google.cloud.spanner.types import DATE_PARAM_TYPE
+from google.cloud.spanner.types import FLOAT64_PARAM_TYPE
+from google.cloud.spanner.types import INT64_PARAM_TYPE
+from google.cloud.spanner.types import STRING_PARAM_TYPE
+from google.cloud.spanner.types import TIMESTAMP_PARAM_TYPE
+
+
+__all__ = [
+    '__version__',
+    'AbstractSessionPool',
+    'BOOL_PARAM_TYPE',
+    'BYTES_PARAM_TYPE',
+    'BurstyPool',
+    'Client',
+    'DATE_PARAM_TYPE',
+    'FLOAT64_PARAM_TYPE',
+    'FixedSizePool',
+    'INT64_PARAM_TYPE',
+    'KeyRange',
+    'KeySet',
+    'STRING_PARAM_TYPE',
+    'TIMESTAMP_PARAM_TYPE',
+]

spanner/google/cloud/spanner/types.py

@@ -0,0 +1,27 @@
+# Copyright 2017 Google Inc. All rights reserved.
+#
+# 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.
+
+"""Types exported from this package."""
+
+from google.cloud.proto.spanner.v1 import type_pb2
+
+
+# Scalar paramter types
+STRING_PARAM_TYPE = type_pb2.Type(code=type_pb2.STRING)
+BYTES_PARAM_TYPE = type_pb2.Type(code=type_pb2.BYTES)
+BOOL_PARAM_TYPE = type_pb2.Type(code=type_pb2.BOOL)
+INT64_PARAM_TYPE = type_pb2.Type(code=type_pb2.INT64)
+FLOAT64_PARAM_TYPE = type_pb2.Type(code=type_pb2.FLOAT64)
+DATE_PARAM_TYPE = type_pb2.Type(code=type_pb2.DATE)
+TIMESTAMP_PARAM_TYPE = type_pb2.Type(code=type_pb2.TIMESTAMP)