Request and store es version info and use to modify the object select…

…or for the number of hits. Issue taraslayshchuk#74

es2csv.py

@@ -6,6 +6,7 @@
 import progressbar
 from backports import csv
 from functools import wraps
+from packaging import version
 
 
 FLUSH_BUFFER = 1000  # Chunk of docs to flush in temp file
@@ -61,6 +62,7 @@ def create_connection(self):
                                          client_cert=self.opts.client_cert, client_key=self.opts.client_key)
         es.cluster.health()
         self.es_conn = es
+        self.es_info = es.info()
 
     @retry(elasticsearch.exceptions.ConnectionError, tries=TIMES_TO_TRY)
     def check_indexes(self):
@@ -124,7 +126,14 @@ def next_scroll(scroll_id):
             print('Sorting by: {}.'.format(', '.join(self.opts.sort)))
 
         res = self.es_conn.search(**search_args)
-        self.num_results = res['hits']['total']
+
+# Breaking change in ES 7.0 for total hits
+# https://www.elastic.co/guide/en/elasticsearch/reference/current/breaking-changes-7.0.html#hits-total-now-object-search-response
+
+        if version.parse(self.es_info['version']['number']) < version.parse("7.0.0"):
+            self.num_results = res['hits']['total']
+        else:
+            self.num_results = res['hits']['total']['value']
 
         print('Found {} results.'.format(self.num_results))
         if self.opts.debug_mode: