Allow .update(set__type='foo') to work without raising an error in ca…

…se 'type' is one of the field. Avoids that it clash with the type operator

docs/changelog.rst

@@ -20,6 +20,7 @@ Development
   it is not recommended to do so (DecimalField uses float/str to store the value, Decimal128Field uses Decimal128).
 - BREAKING CHANGE: When using ListField(EnumField) or DictField(EnumField), the values weren't always cast into the Enum (#2531)
 - BREAKING CHANGE (bugfix) Querying ObjectIdField or ComplexDateTimeField with None will no longer raise a ValidationError (#2681)
+- Allow updating a field that has an operator name e.g. "type" with .update(set__type="foo"). It was raising an error previously. #2595
 
 Changes in 0.25.0
 =================

mongoengine/queryset/transform.py

@@ -264,12 +264,24 @@ def update(_doc_cls=None, **update):
             op = operator_map.get(op, op)
 
         match = None
-        if len(parts) > 1 and parts[-1] in COMPARISON_OPERATORS:
-            match = parts.pop()
 
-        # Allow to escape operator-like field name by __
-        if len(parts) > 1 and parts[-1] == "":
-            parts.pop()
+        if len(parts) == 1:
+            # typical update like set__field
+            # but also allows to update a field named like a comparison operator
+            # like set__type = "something" (without clashing with the 'type' operator)
+            pass
+        elif len(parts) > 1:
+            # can be either an embedded field like set__foo__bar
+            # or a comparison operator as in pull__foo__in
+            if parts[-1] in COMPARISON_OPERATORS:
+                match = parts.pop()  # e.g. pop 'in' from pull__foo__in
+
+            # Allow to escape operator-like field name by __
+            # e.g. in the case of an embedded foo.type field
+            # Doc.objects().update(set__foo__type="bar")
+            # see https://github.com/MongoEngine/mongoengine/pull/1351
+            if parts[-1] == "":
+                match = parts.pop()  # e.g. pop last '__' from set__foo__type__
 
         if _doc_cls:
             # Switch field names to proper names [set in Field(name='foo')]

tests/queryset/test_transform.py

@@ -275,7 +275,7 @@ class Doc(Document):
         assert Doc.objects(df__type=2).count() == 1  # str
         assert Doc.objects(df__type=16).count() == 1  # int
 
-    def test_last_field_name_like_operator(self):
+    def test_embedded_field_name_like_operator(self):
         class EmbeddedItem(EmbeddedDocument):
             type = StringField()
             name = StringField()
@@ -295,6 +295,30 @@ class Doc(Document):
         assert 1 == Doc.objects(item__type__="sword").count()
         assert 0 == Doc.objects(item__type__="axe").count()
 
+    def test_regular_field_named_like_operator(self):
+        class SimpleDoc(Document):
+            size = StringField()
+            type = StringField()
+
+        SimpleDoc.drop_collection()
+        SimpleDoc(type="ok", size="ok").save()
+
+        qry = transform.query(SimpleDoc, type="testtype")
+        assert qry == {"type": "testtype"}
+
+        assert SimpleDoc.objects(type="ok").count() == 1
+        assert SimpleDoc.objects(size="ok").count() == 1
+
+        update = transform.update(SimpleDoc, set__type="testtype")
+        assert update == {"$set": {"type": "testtype"}}
+
+        SimpleDoc.objects.update(set__type="testtype")
+        SimpleDoc.objects.update(set__size="testsize")
+
+        s = SimpleDoc.objects.first()
+        assert s.type == "testtype"
+        assert s.size == "testsize"
+
     def test_understandable_error_raised(self):
         class Event(Document):
             title = StringField()