From 433f10ef93cbfa2d2f0a8cb704e8333704ebf362 Mon Sep 17 00:00:00 2001
From: Erdenezul Batmunkh <erdenezul@shine.mn>
Date: Mon, 31 Jul 2017 05:15:23 +0000
Subject: [PATCH] position support singular value #1565

---
 mongoengine/queryset/transform.py | 17 ++++++++++-------
 tests/queryset/queryset.py        |  5 +++++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/mongoengine/queryset/transform.py b/mongoengine/queryset/transform.py
index b9c8b130..b01d3d41 100644
--- a/mongoengine/queryset/transform.py
+++ b/mongoengine/queryset/transform.py
@@ -304,10 +304,6 @@ def update(_doc_cls=None, **update):
             value = {match: value}
 
         key = '.'.join(parts)
-        position = None
-        if parts[-1].isdigit() and isinstance(value, (list, tuple, set)):
-            key = parts[0]
-            position = int(parts[-1])
 
         if not op:
             raise InvalidQueryError('Updates must supply an operation '
@@ -339,11 +335,18 @@ def update(_doc_cls=None, **update):
                 value = {key: value}
         elif op == 'addToSet' and isinstance(value, list):
             value = {key: {'$each': value}}
-        elif op == 'push' and isinstance(value, list):
-            if position is not None:
+        elif op == 'push':
+            if parts[-1].isdigit() and op == 'push':
+                key = parts[0]
+                position = int(parts[-1])
+                # position modifier must appear with each.
+                if not isinstance(value, (set, tuple, list)):
+                    value = [value]
                 value = {key: {'$each': value, '$position': position}}
-            else:
+            elif isinstance(value, list):
                 value = {key: {'$each': value}}
+            else:
+                value = {key: value}
         else:
             value = {key: value}
         key = '$' + op
diff --git a/tests/queryset/queryset.py b/tests/queryset/queryset.py
index f4e4670d..fe97b765 100644
--- a/tests/queryset/queryset.py
+++ b/tests/queryset/queryset.py
@@ -1925,6 +1925,11 @@ class QuerySetTest(unittest.TestCase):
         post.reload()
         self.assertEqual(post.tags, ['mongodb', 'python', 'java'])
 
+        #test push with singular value
+        BlogPost.objects.filter(id=post.id).update(push__tags__0='scala')
+        post.reload()
+        self.assertEqual(post.tags, ['scala', 'mongodb', 'python', 'java'])
+
     def test_update_push_and_pull_add_to_set(self):
         """Ensure that the 'pull' update operation works correctly.
         """