code: def set_field_value(self, field_name, value):
          
          self.view._json_params[field_name] = value
          if field_name in self.fields:
              self.fields[field_name].new_value = value
              return
  
          fields = FieldData.from_dict({field_name: value}, self.model)
          self.fields.update(fields)
docs: Set value of request field named `field_name`.
  
          Use this method to apply changes to object which is affected
          by request. Values are set on `view._json_params` dict.
  
          If `field_name` is not affected by request, it is added to
          `self.fields` which makes field processors which are connected
          to `field_name` to be triggered, if they are run after this
          method call(connected to events after handler that performs
          method call).
  
          :param field_name: Name of request field value of which should
              be set.
          :param value: Value to be set.