inancgumus/learngo · error

record.domain cannot be empty

Error message

record.domain cannot be empty

What it means

validate() is called after UnmarshalText/UnmarshalJSON parse a record; it rejects records whose domain field is empty. The library treats domain as the mandatory primary key of a log record, so a record without one is invalid.

Source

Thrown at logparser/v5/pipe/record.go:96

func (r *record) MarshalJSON() ([]byte, error) {
	rj := recordJSON{r.domain, r.page, r.visits, r.uniques}
	return json.Marshal(rj)
}

// parseStr helps UnmarshalText for string to positive int parsing.
func parseStr(name, v string) (int, error) {
	n, err := strconv.Atoi(v)
	if err != nil {
		return 0, fmt.Errorf("Record.UnmarshalText %q: %v", name, err)
	}
	return n, nil
}

// validate whether a parsed record is valid or not.
func validate(r record) (err error) {
	switch {
	case r.domain == "":
		err = errors.New("record.domain cannot be empty")
	case r.page == "":
		err = errors.New("record.page cannot be empty")
	case r.visits < 0:
		err = errors.New("record.visits cannot be negative")
	case r.uniques < 0:
		err = errors.New("record.uniques cannot be negative")
	}
	return
}

View on GitHub (pinned to 3c475a78e5)

Solutions

1. Ensure every input record includes a non-empty domain before unmarshaling.
2. Trim and validate input columns; drop or repair rows missing the domain.
3. Handle the error per-record and log/skip invalid rows.
4. Add a schema check on the source data (e.g. require a domain column).

Example fix

// before
{"page":"/home","visits":10}
// after
{"domain":"example.com","page":"/home","visits":10}

if strings.TrimSpace(rec.Domain) == "" {
    return errors.New("record skipped: missing domain")
}
_ = json.Unmarshal(data, &rec) // then rec.Validate()

func hasDomain(r record) bool { return strings.TrimSpace(r.domain) != "" }

var rec record
err := rec.UnmarshalJSON(data)
if err != nil {
    if strings.Contains(err.Error(), "record.domain cannot be empty") {
        log.Printf("dropping record without domain: %s", data)
        return nil
    }
    return err
}

When it happens

Trigger: Unmarshaling a text/JSON record where the domain field is missing, null, or set to "".

Common situations: A CSV/JSON row with a missing column; an upstream exporter omitting the domain key; whitespace-only values that were not trimmed.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• record.page cannot be empty
• record.domain cannot be empty|record.page cannot be empty|re
• invalid number
• record.visits cannot be negative
• record.uniques cannot be negative

AI-assisted analysis of inancgumus/learngo@3c475a78e5 (2026-09-02). Data as JSON: /api/errors/956c49ba6fdaf77d. Report an issue: GitHub.