code: func (f FieldDefinition) ConvertFromModel(name string, value interface{}) (interface{}, error) {
  	if f.Required && value == nil {
  		return nil, fmt.Errorf("Value %s is required", name)
  	}
  	return f.Type.ConvertFromModel(value)
  }
docs: // ConvertFromModel converts a field value for use in the REST API layer