dgraph-io/dgraph · error

Unknown value type for nquad: %+v

Error message

Unknown value type for nquad: %+v

What it means

ToEdgeUsing switches on nq.valueType() to decide whether to build a UID edge or a value edge. If the N-Quad's value type is none of the known kinds (ValueUid, ValuePlain, ValueMulti), the library cannot represent it as an edge and returns this error from the default branch.

Solutions

1. Build N-Quads via the RDF parser instead of hand-filling api.NQuad so ValueType is derived correctly
2. Print the offending nquad (%+v) and check its ValueType/ObjectValue fields against the supported x.Value* constants
3. Upgrade/align client and server versions so the ValueType enum matches what dql supports
4. If the value is a literal, ensure ObjectId is set (not empty) so valueType() classifies it as ValuePlain

Example fix

// before
nq := api.NQuad{Subject: "0x1", Predicate: "name"} // no object/value set
// after
nq := api.NQuad{Subject: "0x1", Predicate: "name", ObjectId: "0x2"}

func knownValueType(nq *api.NQuad) bool {
  switch nq.ValueType {
  case api.NQuad_VALUE_UID, api.NQuad_VALUE_STRING, api.NQuad_VALUE_DATETIME, api.NQuad_VALUE_INT, api.NQuad_VALUE_FLOAT, api.NQuad_VALUE_BOOL:
    return true
  }
  return nq.ObjectId != "" || nq.ObjectValue != nil
}

When it happens

Trigger: Passing a malformed or programmatically constructed api.NQuad to ToEdgeUsing whose ObjectId/value encoding does not map to any known ValueType — e.g. an NQuad built by hand with an unset or unsupported ValueType field.

Common situations: Constructing api.NQuad structs in Go instead of parsing RDF text (parser normally sets ValueType); version drift where a ValueType enum value isn't handled by this Dgraph version; corrupted intermediate representations from custom tooling.

Related errors

• ObjectId should be > 0 for nquad: %+v
• Subject should be > 0 for nquad: %+v
• Argument cannot be "uid"
• Attr: [ ] should have @lang directive in schema to mutate…
• Attribute is not indexed.

AI-assisted analysis of dgraph-io/dgraph@759e242be6 (2026-09-01). Data as JSON: /api/errors/02a4667e06d61be9. Report an issue: GitHub.

Appendix: source

Thrown at dql/mutation.go:194

	if sUid == 0 {
		return nil, errors.Errorf("Subject should be > 0 for nquad: %+v", nq)
	}

	switch nq.valueType() {
	case x.ValueUid:
		oUid, err := toUid(nq.ObjectId, newToUid)
		if err != nil {
			return nil, err
		}
		if oUid == 0 {
			return nil, errors.Errorf("ObjectId should be > 0 for nquad: %+v", nq)
		}
		edge = nq.CreateUidEdge(sUid, oUid)
	case x.ValuePlain, x.ValueMulti:
		edge, err = nq.CreateValueEdge(sUid)
	default:
		return &emptyEdge, errors.Errorf("Unknown value type for nquad: %+v", nq)
	}
	if err != nil {
		return nil, err
	}
	return edge, nil
}

func copyValue(out *pb.DirectedEdge, nq NQuad) error {
	var err error
	var t types.TypeID
	if out.Value, t, err = byteVal(nq); err != nil {
		return err
	}
	out.ValueType = t.Enum()
	return nil
}

func (nq NQuad) valueType() x.ValueTypeInfo {

View on GitHub (pinned to 759e242be6)