code: def initial_value(self, field_name: str = None):
          
          if self._meta.get_field(field_name).get_internal_type() == 'ForeignKey':
              if not field_name.endswith('_id'):
                  field_name = field_name+'_id'
  
          attribute = self._diff_with_initial.get(field_name, None)
  
          if not attribute:
              return None
  
          return attribute[0]
docs: Get initial value of field when model was instantiated.