feat(BaseService): support stream=True in BaseService.send()

Fixes: arf/planning-sdk-squad/issues/901

This change allows generated operation code to pass 'stream=True' to
the BaseService.send() method, which will in turn pass it on to the
underlying requests.request() method.  The net result is that
the response body (even if it is a JSON object) will be "streamed",
which means it will be made available via the requests.Response object
rather than consumed and set on the DetailedResponse object.
To access the streamed response, simply retrieve the requests.Response
object by calling DetailedResponse.get_result(), then use the "iter_content"
method on the returned requests.Response instance.

ibm_cloud_sdk_core/base_service.py

@@ -211,13 +211,18 @@ def send(self, request: requests.Request, **kwargs) -> DetailedResponse:
         if self.disable_ssl_verification:
             kwargs['verify'] = False
 
+        # Check to see if the caller specified the 'stream' argument.
+        stream_response = kwargs.get('stream') or False
+
         try:
             response = requests.request(**request, cookies=self.jar, **kwargs)
 
             if 200 <= response.status_code <= 299:
                 if response.status_code == 204 or request['method'] == 'HEAD':
                     # There is no body content for a HEAD request or a 204 response
                     result = None
+                elif stream_response:
+                    result = response
                 elif not response.text:
                     result = None
                 else:

test/test_base_service.py

@@ -7,6 +7,7 @@
 from typing import Optional
 import pytest
 import responses
+import requests
 import jwt
 from ibm_cloud_sdk_core import BaseService, DetailedResponse
 from ibm_cloud_sdk_core import ApiException
@@ -80,6 +81,13 @@ def head_request(self) -> DetailedResponse:
         response = self.send(request)
         return response
 
+    def get_document_as_stream(self) -> DetailedResponse:
+        params = {'version': self.version}
+        url = '/v1/streamjson'
+        request = self.prepare_request(method='GET', url=url, params=params)
+        response = self.send(request, stream=True)
+        return response
+
 
 def get_access_token() -> str:
     access_token_layout = {
@@ -135,6 +143,45 @@ def test_url_encoding():
     assert 'version=2017-07-07' in responses.calls[0].request.url
 
 
+@responses.activate
+def test_stream_json_response():
+    service = AnyServiceV1('2017-07-07', authenticator=NoAuthAuthenticator())
+
+    path = '/v1/streamjson'
+    test_url = service.default_url + path
+
+    expected_response = json.dumps({"id": 1, "rev": "v1", "content": "this is a document"})
+
+    # print("Expected response: ", expected_response)
+
+    # Simulate a JSON response
+    responses.add(
+        responses.GET,
+        test_url,
+        status=200,
+        body=expected_response,
+        content_type='application/json')
+
+    # Invoke the operation and receive an "iterable" as the response
+    response = service.get_document_as_stream()
+
+    assert response is not None
+    assert len(responses.calls) == 1
+
+    # retrieve the requests.Response object from the DetailedResponse
+    resp = response.get_result()
+    assert isinstance(resp, requests.Response)
+    assert hasattr(resp, "iter_content")
+
+    # Retrieve the response body, one chunk at a time.
+    actual_response = ''
+    for chunk in resp.iter_content(chunk_size=3):
+        actual_response += chunk.decode("utf-8")
+
+    # print("Actual response: ", actual_response)
+    assert actual_response == expected_response
+
+
 @responses.activate
 def test_http_config():
     service = AnyServiceV1('2017-07-07', authenticator=NoAuthAuthenticator())