Refactor storage sample for better code-inclusion

Author: Jerjou Cheng

storage/api/list_objects.py

@@ -13,9 +13,6 @@
 # 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 all]
-
 """Command-line sample application for listing all objects in a bucket using
 the Cloud Storage API.
 
@@ -30,11 +27,12 @@
 import json
 
 from googleapiclient import discovery
+
 from oauth2client.client import GoogleCredentials
 
 
-def main(bucket):
-    # [START list_bucket]
+def create_service():
+    """Creates the service object for calling the Cloud Storage API."""
     # Get the application default credentials. When running locally, these are
     # available after running `gcloud init`. When running on compute
     # engine, these are available from the environment.
@@ -44,26 +42,41 @@ def main(bucket):
     # the 'storage' service, at version 'v1'.
     # You can browse other available api services and versions here:
     #     https://developers.google.com/api-client-library/python/apis/
-    service = discovery.build('storage', 'v1', credentials=credentials)
+    return discovery.build('storage', 'v1', credentials=credentials)
+
+
+def get_bucket_metadata(bucket):
+    """Retrieves metadata about the given bucket."""
+    service = create_service()
 
     # Make a request to buckets.get to retrieve a list of objects in the
     # specified bucket.
     req = service.buckets().get(bucket=bucket)
-    resp = req.execute()
-    print(json.dumps(resp, indent=2))
-    # [END list_bucket]
+    return req.execute()
+
+
+def list_bucket(bucket):
+    """Returns a list of metadata of the objects within the given bucket."""
+    service = create_service()
 
     # Create a request to objects.list to retrieve a list of objects.
     fields_to_return = \
         'nextPageToken,items(name,size,contentType,metadata(my-key))'
     req = service.objects().list(bucket=bucket, fields=fields_to_return)
 
+    all_objects = []
     # If you have too many items to list in one request, list_next() will
     # automatically handle paging with the pageToken.
     while req:
         resp = req.execute()
-        print(json.dumps(resp, indent=2))
+        all_objects.extend(resp.get('items', []))
         req = service.objects().list_next(req, resp)
+    return all_objects
+
+
+def main(bucket):
+    print(json.dumps(get_bucket_metadata(bucket), indent=2))
+    print(json.dumps(list_bucket(bucket), indent=2))
 
 
 if __name__ == '__main__':
@@ -75,4 +88,3 @@ def main(bucket):
     args = parser.parse_args()
 
     main(args.bucket)
-# [END all]