cayleygraph/cayley · error

unknown quad format %q

Error message

unknown quad format %q

What it means

This error means QuadReaderFor could not resolve the quad serialization format for the given type string. The loader first tries registered format writers (via writerQuadTypes/format registry) and then falls back to quad.FormatByName(typ); if both return nil, the name is not a known quad format, so loading is aborted. It exists to fail fast on a misspelled or unsupported --format / configuration value before any data is read.

Source

Thrown at internal/load.go:102

	switch typ {
	case "cquad", "nquad": // legacy
		qr = nquads.NewReader(r, false)
	default:
		var format *quad.Format
		if typ == "" {
			name := filepath.Base(path)
			name = strings.TrimSuffix(name, ".gz")
			name = strings.TrimSuffix(name, ".bz2")
			format = quad.FormatByExt(filepath.Ext(name))
			if format == nil {
				typ = "nquads"
			}
		}
		if format == nil {
			format = quad.FormatByName(typ)
		}
		if format == nil {
			err = fmt.Errorf("unknown quad format %q", typ)
		} else if format.Reader == nil {
			err = fmt.Errorf("decoding of %q is not supported", typ)
		}
		if err != nil {
			if c != nil {
				c.Close()
			}
			return nil, err
		}
		qr = format.Reader(r)
	}
	if c != nil {
		return readCloser{ReadCloser: qr, close: c.Close}, nil
	}
	return qr, nil
}

// DecompressAndLoad will load or fetch a graph from the given path, decompress

View on GitHub (pinned to 81dcd7d73e)

Solutions

1. Check the format name against quad.RegisterFormat registrations (e.g. "nquads", "jsonld"); fix the spelling in the CLI flag or config.
2. If the file extension drives detection, rename the file to the expected extension or pass the format explicitly.
3. Run `cayley ` with the supported formats listed in the docs to confirm which names exist in your build.
4. If the format genuinely does not exist, convert the data to nquads first (e.g. with a serializer) and load that.

Example fix

// before
cayley load --format nquad data.nq
// after
cayley load --format nquads data.nq

if quad.FormatByName(formatName) == nil {
	return fmt.Errorf("unsupported quad format: %q (use nquads, jsonld, ...)", formatName)
}
_, err := internal.QuadReaderFor(ctx, path, formatName, compress)

When it happens

Trigger: Calling internal.QuadReaderFor (directly or via internal.DecompressAndLoad from internal.Load, e.g. `cayley load`) with a file whose detected/derived typ string has no registered format: a misspelled format name like 'nquad' instead of 'nquads', or an unknown file extension, or passing a typ that quad.FormatByName does not recognize.

Common situations: Typo in the format flag or config (e.g. "nquad", "NQuads", "triples"); loading a file with an unrecognized extension; a Cayley build/version where a given format is not registered; scripts hard-coding a format string from another tool.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• decoding of %q is not supported
• ErrEmptyPath
• db: failed to load data: %v
• HTTP Request needed
• cannot count iterator without a valid context

AI-assisted analysis of cayleygraph/cayley@81dcd7d73e (2026-09-06). Data as JSON: /api/errors/7f0e6f36c6390b04. Report an issue: GitHub.