{"record":{"id":"d91ab8efe4488eb1","repo":"dgraph-io/dgraph","slug":"objectid-should-be-0-for-nquad-v","errorCode":null,"errorMessage":"ObjectId should be > 0 for nquad: %+v","messagePattern":"ObjectId should be > 0 for nquad: %\\+v","errorType":"validation","errorClass":null,"httpStatus":null,"severity":"error","filePath":"dql/mutation.go","lineNumber":188,"sourceCode":"func (nq NQuad) ToEdgeUsing(newToUid map[string]uint64) (*pb.DirectedEdge, error) {\n\tvar edge *pb.DirectedEdge\n\tsUid, err := toUid(nq.Subject, newToUid)\n\tif err != nil {\n\t\treturn nil, err\n\t}\n\n\tif sUid == 0 {\n\t\treturn nil, errors.Errorf(\"Subject should be > 0 for nquad: %+v\", nq)\n\t}\n\n\tswitch nq.valueType() {\n\tcase x.ValueUid:\n\t\toUid, err := toUid(nq.ObjectId, newToUid)\n\t\tif err != nil {\n\t\t\treturn nil, err\n\t\t}\n\t\tif oUid == 0 {\n\t\t\treturn nil, errors.Errorf(\"ObjectId should be > 0 for nquad: %+v\", nq)\n\t\t}\n\t\tedge = nq.CreateUidEdge(sUid, oUid)\n\tcase x.ValuePlain, x.ValueMulti:\n\t\tedge, err = nq.CreateValueEdge(sUid)\n\tdefault:\n\t\treturn &emptyEdge, errors.Errorf(\"Unknown value type for nquad: %+v\", nq)\n\t}\n\tif err != nil {\n\t\treturn nil, err\n\t}\n\treturn edge, nil\n}\n\nfunc copyValue(out *pb.DirectedEdge, nq NQuad) error {\n\tvar err error\n\tvar t types.TypeID\n\tif out.Value, t, err = byteVal(nq); err != nil {\n\t\treturn err","sourceCodeStart":170,"sourceCodeEnd":206,"githubUrl":"https://github.com/dgraph-io/dgraph/blob/759e242be62c91f8d084da06ad0c8d21256d9c07/dql/mutation.go#L170-L206","documentation":"In ToEdgeUsing, when the N-Quad's object is a UID-valued edge (x.ValueUid), the object is resolved with toUid; if the resulting object UID is 0 the edge would point at nothing, so the library returns this error. Only UID-typed objects take this path; literal-valued objects go through CreateValueEdge and are validated elsewhere.","triggerScenarios":"Calling ToEdgeUsing with an N-Quad whose object is a UID reference (another node or blank node) that resolves to 0 — e.g. a blank node _:bob absent from the newToUid map, or an explicit object UID of 0.","commonSituations":"Typos in blank-node labels between subject and object positions of quads; mutations referencing nodes that were never upserted/allocated; copying example code that uses UIDs that don't exist in your graph.","solutions":["Verify the object blank-node label matches exactly (including case) the label used where the node is created in newToUid","Pre-assign UIDs for every referenced node (e.g. via upsert blocks or a first mutation pass) before building edges to them","Confirm explicit object UIDs are non-zero and correspond to existing nodes","Inspect the nquad in the error message to identify the failing object value"],"exampleFix":"// before\ntoUid := map[string]uint64{\"_:alice\": 0x1001} // _:bob missing\n// after\ntoUid := map[string]uint64{\"_:alice\": 0x1001, \"_:bob\": 0x1002}","handlingStrategy":"validation","validationCode":"func validObject(nq *api.NQuad, toUid map[string]uint64) bool {\n  if nq.ObjectId == \"\" { return nq.ObjectValue != nil }\n  if uid, err := strconv.ParseUint(nq.ObjectId, 0, 64); err == nil { return uid != 0 }\n  if strings.HasPrefix(nq.ObjectId, \"_:\") { return toUid[nq.ObjectId] != 0 }\n  return false\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Assign UIDs to all referenced nodes before creating edges to them","Use upsert blocks or a two-pass mutation for blank-node references","Match blank-node labels exactly between subject and object positions"],"tags":["dgraph","dql","mutation","uid-resolution"],"backgroundTag":"invalid-uid-in-mutation","analyzedSha":"759e242be62c91f8d084da06ad0c8d21256d9c07","analyzedAt":"2026-09-01T14:42:12.034Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}