inancgumus/learngo · error

line #%d: %s

Error message

line #%d: %s

What it means

The report parser's Parse method parses each line via parse(line) and, on failure, records the error in p.lerr prefixed with the 1-based line counter p.lines ('line #%d: %s') and returns, stopping further parsing. The stored error is reported after the whole file has been streamed.

Source

Thrown at logparser/testing/report/parser.go:37

	lerr    error    // the last error occurred
}

// New returns a new parsing state.
func New() *Parser {
	return &Parser{summary: newSummary()}
}

// Parse parses a log line and adds it to the summary.
func (p *Parser) Parse(line string) {
	// if there was an error do not continue
	if p.lerr != nil {
		return
	}

	// chain the parser's error to the result's
	res, err := parse(line)
	if p.lines++; err != nil {
		p.lerr = fmt.Errorf("line #%d: %s", p.lines, err)
		return
	}

	p.summary.update(res)
}

// Summarize summarizes the parsing results.
// Only use it after the parsing is done.
func (p *Parser) Summarize() *Summary {
	return p.summary
}

// Err returns the last error encountered
func (p *Parser) Err() error {
	return p.lerr
}

View on GitHub (pinned to 3c475a78e5)

Solutions

  1. Fix or remove the line indicated by 'line #N' in the error
  2. Validate lines before Parse (3 whitespace-separated fields, non-negative integers)
  3. Decide on a policy: fail-fast (current) vs. collecting all bad lines and reporting a summary

Example fix

// before
if p.lines++; err != nil {
    p.lerr = fmt.Errorf("line #%d: %s", p.lines, err)
    return
}
// after
if p.lines++; err != nil {
    p.skipped++
    p.lerr = fmt.Errorf("line #%d: %s", p.lines, err) // keep last; continue parsing
    return
}
Defensive patterns

Strategy: validation

Validate before calling

for i, line := range lines {
    if len(strings.Fields(line)) != 3 {
        log.Printf("line %d malformed, skipping", i+1)
        continue
    }
    p.Parse(line)
}

Type guard

func isReportLine(line string) bool {
    fs := strings.Fields(line)
    if len(fs) != 3 { return false }
    v, err1 := strconv.Atoi(fs[1]); t, err2 := strconv.Atoi(fs[2])
    return err1 == nil && err2 == nil && v >= 0 && t >= 0
}

Try / catch

if p.lerr != nil {
    log.Fatalf("parsing stopped: %v", p.lerr) // p.lerr already contains 'line #N: ...'
}

Prevention

When it happens

Trigger: Calling Parse with a line whose field count != 3 (error 33) or whose numeric fields fail field.atoi (error 34); the wrapped message identifies the offending line number.

Common situations: Log lines missing the visits or time-spent column, negative visit counts, non-numeric numbers ('12,000'), or headers/blank lines accidentally fed to the parser.

Related errors

AI-assisted analysis of inancgumus/learngo@3c475a78e5 (2026-09-02). Data as JSON: /api/errors/8a387a4c2dea44da. Report an issue: GitHub.