Exit appropriately when there are no tweets in the collection

lib/utils.py

@@ -416,7 +416,13 @@ def get_page_index_fast(
         page = collection.find({"id": {"$lt": last_id}})\
                          .sort("id", pymongo.DESCENDING)\
                          .limit(page_size)
+        try:
             pages.append(page[0]["id"])
+        except IndexError as exc:
+            if collection.count() == 0:
+                raise NoTweetsException
+            else:
+                raise exc
         try:
             last_id = page[page_size - 1]["id"]
         except IndexError:
@@ -525,3 +531,11 @@ class TweetConversionException(Exception):
         """
         self.message = message
         self.tweet = tweet
+
+
+class NoTweetsException(Exception):
+    """
+    Should be raised when not even 1 tweet is found in the collection
+    """
+
+    pass

pymongoexport_csv.py

@@ -71,7 +71,16 @@ if args.recovery:
 else:
     client = pymongo.MongoClient(args.host, args.port)
     database_tweets = client[args.database]["tweets"]
-    page_index = utils.get_page_index_fast(database_tweets, args.pagesize)
+    try:
+        page_index = utils.get_page_index_fast(
+            database_tweets, args.pagesize)
+    except utils.NoTweetsException:
+        logger.error("Collection has no tweets")
+        os.system('spd-say "Collection has no tweets"')
+        sys.exit(0)
+    except Exception:
+        os.system("spd-say 'Something really bad happened!'")
+        sys.exit(1)
     client.close()
     logger.debug(
         "Database {} partitioned in {} pages of {} tweets (maximum)"