Retrieve ARKINDEX_CORPUS_ID in create_entity when corpus is None

Closes #61 (closed)

arkindex_worker/worker/entity.py

 # -*- coding: utf-8 -*-
-
-
+import os
 from enum import Enum
 
 from arkindex_worker import logger
@@ -19,11 +18,16 @@ class EntityType(Enum):
 
 
 class EntityMixin(object):
-    def create_entity(self, element, name, type, corpus, metas=None, validated=None):
+    def create_entity(
+        self, element, name, type, corpus=None, metas=None, validated=None
+    ):
         """
         Create an entity on the given corpus through API
         Return the ID of the created entity
         """
+        if corpus is None:
+            corpus = os.environ.get("ARKINDEX_CORPUS_ID")
+
         assert element and isinstance(
             element, (Element, CachedElement)
         ), "element shouldn't be null and should be an Element or CachedElement"