Response streaming (#9975)

* Add python sample for response streaming.

* Add python response streaming sample.

* Changed prefix to include functions.

* Removed long list of dependencies

* Adding pytest dependency.

Author: janell-chen

functions/v2/response_streaming/main.py

@@ -0,0 +1,51 @@
+# Copyright 2023 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.
+
+# [START functions_response_streaming]
+from flask import Response, stream_with_context
+
+import functions_framework
+from google.cloud import bigquery
+
+# Construct a BigQuery client object.
+client = bigquery.Client()
+
+
+@functions_framework.http
+def stream_big_query_output(request):
+    """HTTP Cloud Function.
+    Args:
+        request (flask.Request): The request object.
+        <https://flask.palletsprojects.com/en/1.1.x/api/#incoming-request-data>
+    Returns:
+        The response text, or any set of values that can be turned into a
+        Response object using `make_response`
+        <https://flask.palletsprojects.com/en/1.1.x/api/#flask.make_response>.
+    """
+    # Example large query from public dataset
+    query = """
+    SELECT abstract
+    FROM `bigquery-public-data.breathe.bioasq`
+    LIMIT 1000
+    """
+    query_job = client.query(query)  # Make an API request.
+
+    def generate():
+        for row in query_job:
+            yield row[0]
+
+    return Response(stream_with_context(generate()))
+
+
+# [END functions_response_streaming]

functions/v2/response_streaming/main_test.py

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+# Copyright 2023 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.
+import flask
+import pytest
+
+import main
+
+
+# Create a fake "app" for generating test request contexts.
+@pytest.fixture(scope="module")
+def app() -> flask.Flask:
+    return flask.Flask(__name__)
+
+
+def test_main(app):
+    with app.test_request_context():
+        response = main.stream_big_query_output(flask.request)
+        assert response.is_streamed
+        assert response.status_code == 200

functions/v2/response_streaming/requirements.txt

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+Flask==2.2.2
+functions-framework==3.3.0
+google-cloud-bigquery==3.6.0
+pytest==7.2.1