update managers

Author: bckohan

src/polymorphic/managers.py

@@ -2,8 +2,10 @@
 The manager class for use in the models.
 """
 
+import inspect
+
 from django.contrib.contenttypes.models import ContentType
-from django.db import models
+from django.db import DEFAULT_DB_ALIAS, models
 
 from polymorphic.query import PolymorphicQuerySet
 
@@ -62,23 +64,35 @@ def create_from_super(self, obj, **kwargs):
         returns obj as an instance of cls.
         """
         cls = self.model
-        import inspect
 
         scls = inspect.getmro(cls)[1]
         if scls is not type(obj):
             raise TypeError(
                 "create_from_super can only be used if obj is one level of inheritance up from cls"
             )
-        ptr = "{}_ptr_id".format(scls.__name__.lower())
-        kwargs[ptr] = obj.id
+
+        import ipdb
+
+        ipdb.set_trace()
+        parent_link_field = None
+        for parent, field in cls._meta.parents.items():
+            if parent is scls:
+                parent_link_field = field
+                break
+        if parent_link_field is None:
+            raise TypeError(f"Could not find parent link field for {scls.__name__}")
+        kwargs[parent_link_field.name] = obj.id
+
         # create the new base class with only fields that apply to  it.
         nobj = cls(**kwargs)
         nobj.save_base(raw=True)
         # force update the content type, but first we need to
         # retrieve a clean copy from the db to fill in the null
         # fields otherwise they would be overwritten.
-        nobj = obj.__class__.objects.get(pk=obj.pk)
-        nobj.polymorphic_ctype = ContentType.objects.get_for_model(cls)
+        nobj = obj.__class__.objects.using(obj._state.db or DEFAULT_DB_ALIAS).get(pk=obj.pk)
+        nobj.polymorphic_ctype = ContentType.objects.using(
+            obj._state.db or DEFAULT_DB_ALIAS
+        ).get_for_model(cls)
         nobj.save()
 
         return nobj.get_real_instance()  # cast to cls