Custom Directives

Learn about custom directives like @backingData, @scope, @idOf, and @oneOf in Viaduct.

Custom directives in Viaduct enhance your GraphQL schema with extra behavior and validation. This page introduces the directives used in the Star Wars demo and links to focused pages for details and examples.

What you will find here

  • @backingData — bind a field to a backing data class for transformation logic.
  • @scope — expose types/fields only to specific scopes (multi-module boundaries).
  • @idOf — mark ID fields/args with their GraphQL type for type-safe Global ID handling.
  • @oneOf — enforce exactly one non-null field in an input object (union-like inputs).

To access scoped fields, include the X-Viaduct-Scopes header in your request.

backingData Directive

Specify backing data classes for fields to separate transformation logic from retrieval.

Scope Directive

Control schema visibility and multi-module access with @scope; Star Wars demo uses an app-level header.

idOf Directive

Bind ID fields to GraphQL types for type-safe Global ID handling in Viaduct.

OneOf Directive

Ensure exactly one non-null field in input objects; works well with @idOf for typed Global IDs.