jackc/pgx · error

unable to scan OID in text format into

Error message

unable to scan OID %d in text format into %v

What it means

DecodeValue on a text-format composite could not plan a scan for one of its fields: PlanScan returned nil for the field's OID into *any. The composite contains a field type the Map has no scan plan for, so the composite cannot be decoded to a generic map.

Solutions

1. Register a codec for the unknown OID in the TypeMap
2. Avoid DecodeValue on composites containing unsupported custom types

When it happens

Trigger: Thrown at pgtype/composite.go:238 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of jackc/pgx@ec1a0befd2 (2026-08-04). Data as JSON: /api/errors/a1a8c660541526ca. Report an issue: GitHub.

Appendix: source

Thrown at pgtype/composite.go:238

	default:
		return nil, fmt.Errorf("unknown format code %d", format)
	}
}

func (c *CompositeCodec) DecodeValue(m *Map, oid uint32, format int16, src []byte) (any, error) {
	if src == nil {
		return nil, nil
	}

	switch format {
	case TextFormatCode:
		scanner := NewCompositeTextScanner(m, src)
		values := make(map[string]any, len(c.Fields))
		for i := 0; scanner.Next() && i < len(c.Fields); i++ {
			var v any
			fieldPlan := m.PlanScan(c.Fields[i].Type.OID, TextFormatCode, &v)
			if fieldPlan == nil {
				return nil, fmt.Errorf("unable to scan OID %d in text format into %v", c.Fields[i].Type.OID, v)
			}

			err := fieldPlan.Scan(scanner.Bytes(), &v)
			if err != nil {
				return nil, err
			}

			values[c.Fields[i].Name] = v
		}

		if err := scanner.Err(); err != nil {
			return nil, err
		}

		return values, nil
	case BinaryFormatCode:
		scanner := NewCompositeBinaryScanner(m, src)
		values := make(map[string]any, len(c.Fields))

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