Use insert_one instead of deprecated one #1899

docs/changelog.rst

@@ -5,7 +5,9 @@ Changelog
 Development
 ===========
 - (Fill this out as you fix issues and develop your features).
-=======
+- Remove deprecated `save()` method and used `insert_one()` #1899
+
+=================
 Changes in 0.16.0
 =================
 - Various improvements to the doc

mongoengine/document.py

@@ -12,7 +12,9 @@
                               TopLevelDocumentMetaclass, get_document)
 from mongoengine.common import _import_class
 from mongoengine.connection import DEFAULT_CONNECTION_NAME, get_db
-from mongoengine.context_managers import switch_collection, switch_db
+from mongoengine.context_managers import (set_write_concern,
+                                          switch_collection,
+                                          switch_db)
 from mongoengine.errors import (InvalidDocumentError, InvalidQueryError,
                                 SaveConditionError)
 from mongoengine.python_support import IS_PYMONGO_3
@@ -429,11 +431,18 @@ def _save_create(self, doc, force_insert, write_concern):
         Helper method, should only be used inside save().
         """
         collection = self._get_collection()
-
-        if force_insert:
-            return collection.insert(doc, **write_concern)
-
-        object_id = collection.save(doc, **write_concern)
+        with set_write_concern(collection, write_concern) as wc_collection:
+            if force_insert:
+                return wc_collection.insert_one(doc).inserted_id
+            # insert_one will provoke UniqueError alongside save does not
+            # therefore, it need to catch and call replace_one.
+            if '_id' in doc:
+                raw_object = wc_collection.find_one_and_replace(
+                    {'_id': doc['_id']}, doc)
+                if raw_object:
+                    return doc['_id']
+
+            object_id = wc_collection.insert_one(doc).inserted_id
 
         # In PyMongo 3.0, the save() call calls internally the _update() call
         # but they forget to return the _id value passed back, therefore getting it back here