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Unions

GraphQL unions can be defined by placing a @gqlUnion docblock directly before a:

  • Type alias of a union of object types
/**
 * A description of my union.
 * @gqlUnion <optional name of the union, if different from type name>
 */
type MyUnion = User | Post;

/** @gqlType */
class User {
  __typename: "User";
  /** @gqlField */
  name: string;
}

/** @gqlType */
class Post {
  __typename: "Post";
  /** @gqlField */
  content: string;

  /** @gqlField */
  author: User;
}
note

All the types referenced in the TypeScript union but be explicitly annotated with @gqlType. Grats will remind you with a helpful error message if you forget.

note

Grats will remind you to add a __typename: "MyType" property to all the types which are members of a union.