Document upload fix

* fixes some minor issues with the document upload

intervention/views.py

@@ -83,13 +83,12 @@ def new_document_view(request: HttpRequest, id: str):
     Returns:
 
     """
-    form = NewDocumentForm(request.POST, request.FILES, user=request.user)
+    intervention = get_object_or_404(Intervention, id=id)
+    form = NewDocumentForm(request.POST or None, request.FILES or None, instance=intervention, user=request.user)
     template = form.template
     if request.method == "POST":
         if form.is_valid():
             doc = form.save()
-            intervention = get_object_or_404(Intervention, id=id)
-            intervention.documents.add(doc)
             messages.success(
                 request,
                 _("Document '{}' added").format(doc.title)