support numeric pks in model form data

Author: timgraham

django_mongodb/fields/auto.py

@@ -23,6 +23,10 @@ def get_prep_value(self, value):
         # like settings.SITE_ID which has a system check requiring an integer.
         if isinstance(value, (ObjectId | int)):
             return value
+        # If a digit doesn't match the length of an ObjectId, treat it as an
+        # integer. Manually assigned IDs won't be 24 digits long.
+        if isinstance(value, str) and value.isdigit() and len(value) != 24:
+            return int(value)
         try:
             return ObjectId(value)
         except errors.InvalidId as e:
@@ -32,7 +36,7 @@ def rel_db_type(self, connection):
         return Field().db_type(connection=connection)
 
     def to_python(self, value):
-        if value is None:
+        if value is None or isinstance(value, int):
             return value
         try:
             return ObjectId(value)