Fix bug in datafile update

portal/models.py

@@ -191,7 +191,7 @@ class DataFile(models.Model):
         super().delete(using, keep_parents)
 
     def save(self, *args, **kwargs):
-        if self.file:
+        if self.file and not self.filename:
             self.filename = self.file.name
         super().save(*args, **kwargs)