cayleygraph/cayley · error

unknown value format: %T

Error message

unknown value format: %T

What it means

toQuadValue converts a stored nosql document back into a quad.Value. The document's value field ("str") must hold a nosql.String; if it holds any other type (nil, nosql.Bool, a number, etc.) the document is corrupt or was written by an incompatible writer, so this error is thrown.

Solutions

1. Inspect the offending document and check which type the "str" field actually holds
2. Re-import the source data (nquads/JSONL) into a fresh store to rebuild the document
3. Verify the store was written and read with the same Cayley version
4. If handling externally-produced documents, validate document shape before calling toQuadValue

Example fix

// before: blindly converting a hash read from disk
v, err := NameOf(h)
// after: validate the document field first
if _, ok := doc[fldValData].(nosql.String); !ok {
    return fmt.Errorf("skipping malformed document %v", doc)
}
v, err := NameOf(h)

if _, ok := doc["str"].(nosql.String); !ok { return fmt.Errorf("document %v has no string value", doc) }

func isStringDoc(d map[string]interface{}) bool { _, ok := d[fldValData].(nosql.String); return ok }

v, err := toQuadValue(doc)
if err != nil {
    log.Warnf("skipping malformed document: %v", err)
    return nil // or fallback
}

When it happens

Trigger: Calling NameOf (or Quad) on a QuadHash whose underlying document lacks a nosql.String under the "str" key — typically a corrupted, hand-edited, or foreign document in the nosql backend.

Common situations: Data written by a different Cayley/nosql version, manual edits to a KV store (bolt/leveldb), or deserialization of a document that never went through toDocumentValue.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• unsupported value: %#v
• unexpected type for bool field: %T
• unexpected type for float field: %T
• unexpected type for int field: %T
• unexpected type for pb field: %T

AI-assisted analysis of cayleygraph/cayley@81dcd7d73e (2026-09-06). Data as JSON: /api/errors/6891884fce98dec1. Report an issue: GitHub.

Appendix: source

Thrown at graph/nosql/quadstore.go:598

	} else if v, ok := d[fldValTime]; ok {
		var vt quad.Time
		switch v := v.(type) {
		case nosql.Time:
			vt = quad.Time(v)
		case nosql.String:
			var t time.Time
			if err := t.UnmarshalJSON([]byte(`"` + string(v) + `"`)); err != nil {
				return nil, err
			}
			vt = quad.Time(t)
		default:
			return nil, fmt.Errorf("unexpected type for bool field: %T", v)
		}
		return vt, nil
	}
	vs, ok := d[fldValData].(nosql.String)
	if !ok {
		return nil, fmt.Errorf("unknown value format: %T", d[fldValData])
	}
	if len(d) == 1 {
		return quad.String(vs), nil
	}
	if ok, _ := d[fldIRI].(nosql.Bool); ok {
		return quad.IRI(vs), nil
	} else if ok, _ := d[fldBNode].(nosql.Bool); ok {
		return quad.BNode(vs), nil
	} else if typ, ok := d[fldType].(nosql.String); ok {
		return quad.TypedString{Value: quad.String(vs), Type: quad.IRI(typ)}, nil
	} else if typ, ok := d[fldLang].(nosql.String); ok {
		return quad.LangString{Value: quad.String(vs), Lang: string(typ)}, nil
	}
	return nil, fmt.Errorf("unsupported value: %#v", d)
}

func (qs *QuadStore) Quad(val graph.Ref) (quad.Quad, error) {
	h := val.(QuadHash)

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