diff --git a/es_search.py b/es_search.py
index 237af6a..7f3402f 100644
--- a/es_search.py
+++ b/es_search.py
@@ -25,9 +25,9 @@ class ESSearch(PyOperator):
         super().__init__()
         try:
             self.client = Elasticsearch(
-                f'https://{host}:{port}',
+                f'http://{host}:{port}' if not ca_certs else f'https://{host}:{port}',
                 ca_certs=ca_certs,
-                basic_auth=(user, password))
+                basic_auth=(user, password) if user and password else None)
             logger.info('Successfully connected to ElasticSearch client.')
         except Exception as e:
             logger.error('Failed to connect ElasticSearch client:\n', e)
@@ -35,7 +35,7 @@ class ESSearch(PyOperator):
 
     def __call__(self, index_name: str, query: dict = {'match_all': {}}, enable: bool=True):
         if not enable:
-            return None
+            return ''
         resp = self.client.search(index=index_name, query=query)
         return resp