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.

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")

View on GitHub (pinned to 81dcd7d73e)

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
• unsupported query type
• unsupported operation: %s
• filters inside expand all are not supported
• Datastore: invalid action

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