I think this works now!!!

busManager/coord/adminClone.py

@@ -1,14 +1,12 @@
 
 from functools import update_wrapper
 from django.contrib.admin import ModelAdmin, helpers
-from django.contrib.admin.utils import unquote
+from django.contrib.admin.utils import unquote, flatten_fieldsets
 from django.utils.functional import lazy
 from django.forms.models import model_to_dict
 from django.forms.formsets import all_valid
 from django.urls import reverse, path
 from django.core.exceptions import PermissionDenied
-from django.http import Http404, HttpResponse
-from django.db.models.fields.files import FieldFile, FileField
 
 
 class CloneModelAdmin(ModelAdmin):
@@ -18,6 +16,7 @@ class CloneModelAdmin(ModelAdmin):
 
     def get_urls(self):
 
+        # Not certain what this wrap() function is exactly. Just copied it from the django admin get_urls function
         def wrap(view):
             def wrapper(*args, **kwargs):
                 return self.admin_site.admin_view(view)(*args, **kwargs)
@@ -30,15 +29,16 @@ class CloneModelAdmin(ModelAdmin):
         new_urlpatterns = [
             path(
                 "<path:object_id>/clone/",
-                wrap(self.clone_view),
+                wrap(self.cloneform_view),
                 name="%s_%s_clone" % info,
             ),
-            # path("clone/", self.clone_view, name="%s_%s_clone" % info),
         ]
 
-        print(new_urlpatterns)
         original_urlpatterns = super(CloneModelAdmin, self).get_urls()
-        return original_urlpatterns + new_urlpatterns
+
+        # Important to add custom urls before the existing ones.
+        # Last entry is <URLPattern '<path:object_id>/'> which will pick up everything not already picked up
+        return new_urlpatterns + original_urlpatterns
 
     def change_view(self, request, object_id, form_url='', extra_context=None):
         print(object_id)
@@ -52,89 +52,87 @@ class CloneModelAdmin(ModelAdmin):
         print(extra_context)
         return super(CloneModelAdmin, self).change_view(request, object_id, form_url, extra_context)
 
-    def clone_view(self, request, object_id, form_url='', extra_context=None):
+    def cloneform_view(self, request, object_id, form_url='', extra_context=None):
         if not self.has_add_permission(request):
             raise PermissionDenied
 
         original_obj = self.get_object(request, object_id)
 
         if original_obj is None:
-            raise Http404
+            return self._get_obj_does_not_exist_redirect(
+                request, self.opts, object_id
+            )
 
-        model_form = self.get_form(request)
+        fieldsets = self.get_fieldsets(request, None)
-        new_obj = self.model()
-        formsets = []
 
-        if False and formsets:
+        model_form = self.get_form(
+            request, None, change=False, fields=flatten_fieldsets(fieldsets)
+        )
 
-            form = model_form(request.POST, request.FILES)
+        if request.method == "POST":
-            if form.is_valid():
+            form = model_form(request.POST)
-                new_obj = self.save_form(request, form, change=False)
+            formsets, inline_instances = self._create_formsets(
+                request,
+                form.instance,
+                change=False,
+            )
+            form_validated = form.is_valid()
+            if form_validated:
+                new_object = self.save_form(request, form, change=False)
+            else:
+                new_object = form.instance
 
-            prefixes = {}
+            if all_valid(formsets) and form_validated:
-            for FormSet, inline in self.get_formsets_with_inlines(request):
+                self.save_model(request, new_object, form, False)
-                prefix = FormSet.get_default_prefix()
+                self.save_related(request, form, formsets, False)
-                prefixes[prefix] = prefixes.get(prefix, 0) + 1
+                change_message = self.construct_change_message(
-                if prefixes[prefix] != 1 or not prefix:
+                    request, form, formsets, False
-                    prefix = "%s-%s" % (prefix, prefixes[prefix])
+                )
-
+                self.log_addition(request, new_object, change_message)
-                request_files = request.FILES
+                return self.response_add(request, new_object)
-                filter_params = {'%s__pk' % original_obj.__class__.__name__.lower(): original_obj.pk}
+            else:
-                inlined_objs = inline.model.objects.filter(**filter_params)
+                form_validated = False
-                for n, inlined_obj in enumerate(inlined_objs.all()):
-                    for field in inlined_obj._meta.fields:
-                        if isinstance(field, FileField) and field not in request_files:
-                            value = field.value_from_object(inlined_obj)
-                            file_field_name = '{}-{}-{}'.format(prefix, n, field.name)
-                            request_files.setdefault(file_field_name, value)
-
-                formset = FormSet(data=request.POST, files=request_files,
-                                  instance=new_obj,
-                                  save_as_new="_saveasnew" in request.POST,  # ????
-                                  prefix=prefix)
-                formsets.append(formset)
-
-                if all_valid(formsets) and form.is_valid():
-                    self.save_model(request, new_obj, form, False)
-                    self.save_related(request, form, formsets, False)
-                    try:
-                        self.log_addition(request, new_obj)
-                    except TypeError:
-                        # In Django 1.9 we need one more param
-                        self.log_addition(request, new_obj, "Cloned object")
-
-                    return self.response_add(request, new_obj, None)
 
         else:
+            new_obj = self.model()
             for field in self.cloneable_fields:
                 setattr(new_obj, field, getattr(original_obj, field))
+            form = model_form(instance=new_obj)
 
-            form = model_form(model_to_dict(new_obj))
+            formsets, inline_instances = self._create_formsets(
+                request, new_obj, change=True
+            )
 
         admin_form = helpers.AdminForm(
             form,
             list(self.get_fieldsets(request)),
             self.get_prepopulated_fields(request),
-            self.get_readonly_fields(request),
+            self.readonly_fields,
             model_admin=self
         )
+        media = self.media
 
-        media = self.media + admin_form.media
+        inline_formsets = self.get_inline_formsets(
+            request, formsets, inline_instances
+        )
+        for inline_formset in inline_formsets:
+            media += inline_formset.media
 
-        inline_admin_formsets = self.get_inline_formsets(request, [], [])
         title = u'{0} {1}'.format(self.clone_verbose_name, original_obj)
 
         context = {
-            'title': title,
+            **self.admin_site.each_context(request),
-            'original': title,
+            "title": title,
-            'adminform': admin_form,
+            "original": title,
-            'is_popup': "_popup" in getattr(request, 'REQUEST', request.GET),
+            "adminform": admin_form,
-            'show_delete': False,
+            "is_popup": "_popup" in request.POST or "_popup" in request.GET,
-            'media': media,
+            "show_delete": False,
-            'inline_admin_formsets': inline_admin_formsets,
+            "media": media,
-            # 'errors': helpers.AdminErrorList(form, self.get_formsets_with_inlines(request)),
+            "inline_admin_formsets": inline_formsets,
-            'app_label': "coord"
+            "errors": helpers.AdminErrorList(form, formsets),
+            **(extra_context or {}),
         }
+
         context.update(extra_context or {})
 
         return self.render_change_form(
@@ -142,5 +140,5 @@ class CloneModelAdmin(ModelAdmin):
             context,
             form_url=form_url,
             change=False,
-            add=False
+            add=True
         )