cayleygraph/cayley · error

expand all is not supported at top level

Error message

expand all is not supported at top level

What it means

The expand-all shorthand (the AnyKey wildcard field, typically `_`) selects all predicates, but this library forbids using it at the top level of a query. Top-level selections must be explicit fields; expand all is only allowed nested inside them.

Solutions

1. Name the starting nodes explicitly at the top level and use expand-all (`_`) only in nested selections
2. Replace the wildcard with the specific predicates you need
3. Enumerate root nodes with a query (e.g. via has/id) before expanding

Example fix

// before
q := "query { _ }"
// after
q := "query { node { _ } }"

const WILDCARD = '_';
function topLevelHasExpandAll(doc) {
  const sel = doc.definitions[0]?.selectionSet?.selections || [];
  return sel.some(s => s.name?.value === WILDCARD);
}

const isExpandAllSelection = (s) => s?.name?.value === '_';

When it happens

Trigger: A top-level selection set in the query operation contains the expand-all wildcard field (AnyKey) as its only selection, causing setToFields to return all=true at the root.

Common situations: Queries like `query { _ }` intending to dump all predicates of every node; users familiar with `_` expansion on nested nodes applying it at the root; exploratory queries generated by tooling.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• expand all cannot be used with other fields
• filters inside expand all are not supported
• unsupported operation
• unsupported query type
• cannot unnest more than one object on

AI-assisted analysis of cayleygraph/cayley@81dcd7d73e (2026-09-06). Data as JSON: /api/errors/51bd3dab260b8a1e. Report an issue: GitHub.

Appendix: source

Thrown at query/graphql/graphql.go:438

	}
	doc, err := parser.Parse(parser.ParseParams{Source: string(data)})
	if err != nil {
		return nil, err
	}
	if len(doc.Definitions) != 1 {
		return nil, fmt.Errorf("unsupported query type")
	}
	def, ok := doc.Definitions[0].(*ast.OperationDefinition)
	if !ok {
		return nil, fmt.Errorf("unsupported query type: %T", doc.Definitions[0])
	} else if def.Operation != "query" {
		return nil, fmt.Errorf("unsupported operation: %s", def.Operation)
	}
	fields, all, err := setToFields(def.SelectionSet, nil)
	if err != nil {
		return nil, err
	} else if all {
		return nil, fmt.Errorf("expand all is not supported at top level")
	}
	return &Query{fields: fields}, nil
}

func setToFields(set *ast.SelectionSet, labels []quad.Value) (out []field, all bool, _ error) {
	if set == nil {
		return
	}
	for _, s := range set.Selections {
		switch sel := s.(type) {
		case *ast.Field:
			fld, err := convField(sel, labels)
			if err != nil {
				return nil, false, err
			}
			if fld.Via == quad.IRI(AnyKey) {
				if len(set.Selections) != 1 {
					return nil, false, fmt.Errorf("expand all cannot be used with other fields")

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