Go Reflection Get current field name but get errors around mismatched types untyped string

type Issue struct {
  SysId  uuid.UUID  `json:"sysid" maelstrom:"required"`
}

func (i *Issue) Unmarshal(data []byte) error {
  err := json.Unmarshal(data, i)
  if err != nil {
    slog.Error(err.Error())
    return err
  }
  fields := reflect.ValueOf(i).Elem()
  for i := 0; i < fields.NumField(); i++ {
    maelstromTags := fields.Type().Field(i).Tag.Get("maelstrom")
    if strings.Contains(maelstromTags, "required") && fields.Field(i).IsZero() {
      return errors.New("Required field is missing." + fields.Field(i))
    }
  }
  return nil
}

In the code above, on the line:

return errors.New("Required field is missing." + fields.Field(i))

I want to include the current field’s name in the error message.

Here is the error I’m getting:

invalid operation: "Required field is missing." + fields.Field(i) (mismatched types untyped string and reflect.Value)

I’ve also tried this:

return errors.New("Required field is missing." + fields.Field(i).String)

But I get this:

invalid operation: "Required field is missing." + fields.Field(i).String (mismatched types untyped string and func() string)

I’ve also tried this:

return errors.New("Required field is missing." + string(fields.Field(i)))

But I get this:

cannot convert fields.Field(i) (value of type reflect.Value) to type string [InvalidConversion]

Can someone point me in the right direction or offer a solution? Thanks!

>Solution :

Get the StructField from the type. Get the field name from the StructType.

return fmt.Errorf("required field is missing: %s", fields.Type().Field(i).Name)