gastownhall/beads · error

get dependents: scan: %w

Error message

get dependents: scan: %w

What it means

This wraps rows.Scan failing while reading a dependent row (issue_id, type) in GetDependentsWithMetadataInTx. Scan errors mean the column values couldn't be decoded into the destination strings — usually a NULL in a NOT NULL-assumed column or an unexpected type.

Source

Thrown at internal/storage/issueops/dependencies.go:1179

//nolint:gosec // G201: table names come from WispTableRouting (hardcoded constants)
func GetDependentsWithMetadataInTx(ctx context.Context, tx DBTX, issueID string) ([]*types.IssueWithDependencyMetadata, error) {
	type depMeta struct {
		depID, depType string
	}

	// Query both dependency tables to find all dependents.
	var deps []depMeta
	for _, depTable := range []string{"dependencies", "wisp_dependencies"} {
		rows, err := tx.QueryContext(ctx, fmt.Sprintf(
			`SELECT issue_id, type FROM %s WHERE %s = ?`, depTable, DepTargetExpr), issueID)
		if err != nil {
			return nil, fmt.Errorf("get dependents from %s: %w", depTable, err)
		}
		for rows.Next() {
			var d depMeta
			if scanErr := rows.Scan(&d.depID, &d.depType); scanErr != nil {
				_ = rows.Close()
				return nil, fmt.Errorf("get dependents: scan: %w", scanErr)
			}
			deps = append(deps, d)
		}
		_ = rows.Close()
		if err := rows.Err(); err != nil {
			return nil, fmt.Errorf("get dependents: rows from %s: %w", depTable, err)
		}
	}

	if len(deps) == 0 {
		return nil, nil
	}

	// Fetch all dependent issues.
	ids := make([]string, len(deps))
	for i, d := range deps {
		ids[i] = d.depID
	}

View on GitHub (pinned to 71377f2769)

Solutions

1. Find the offending row: SELECT issue_id, type FROM <named table> WHERE issue_id IS NULL OR type IS NULL.
2. Backfill/repair NULL or malformed rows, then add a NOT NULL constraint if appropriate.
3. If NULLs are expected, they must be fixed at the data layer — this code scans into plain string and cannot accept them.
4. Confirm the driver/schema column types match (VARCHAR/TEXT, not BLOB or int).

Example fix

// before: nullable columns break Scan(&d.depID, &d.depType)
// after: clean data and enforce NOT NULL
UPDATE dependencies SET type = 'blocks' WHERE type IS NULL;
ALTER TABLE dependencies MODIFY type VARCHAR(32) NOT NULL;

// Detect rows that would fail Scan before calling the API
rows, err := tx.QueryContext(ctx, `SELECT issue_id, type FROM dependencies WHERE issue_id IS NULL OR type IS NULL
    UNION ALL SELECT issue_id, type FROM wisp_dependencies WHERE issue_id IS NULL OR type IS NULL`)
if err != nil { return err }
defer rows.Close()
if rows.Next() { return errors.New("NULL dependency rows found; clean data before querying") }

func isScanErr(err error) bool {
    return err != nil && strings.Contains(err.Error(), "scan")
}

deps, err := GetDependentsWithMetadataInTx(ctx, tx, issueID)
if err != nil {
    if strings.Contains(err.Error(), "scan") {
        return fmt.Errorf("data integrity problem in dependency table: %w", err)
    }
    return err
}

When it happens

Trigger: GetDependentsWithMetadataInTx iterates rows from dependencies/wisp_dependencies and a row has NULL issue_id or type, or a column type the driver cannot convert to string.

Common situations: Rows inserted by older versions or external tools with NULL type values; schema altered to nullable after the code assumed NOT NULL; using a driver with strict type conversion (e.g. refusing to scan non-string types into string).

Related errors

• failed to begin transaction: %w
• failed to recompute is_blocked: %w
• failed to commit is_blocked repairs: %w
• failed to query orphaned dependencies: %w
• row iteration error: %w

AI-assisted analysis of gastownhall/beads@71377f2769 (2026-08-30). Data as JSON: /api/errors/605dda39453349e1. Report an issue: GitHub.