UniqueFragmentNamesRule.mjs 883 B

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  1. import { GraphQLError } from '../../error/GraphQLError.mjs';
  2. /**
  3. * Unique fragment names
  4. *
  5. * A GraphQL document is only valid if all defined fragments have unique names.
  6. *
  7. * See https://spec.graphql.org/draft/#sec-Fragment-Name-Uniqueness
  8. */
  9. export function UniqueFragmentNamesRule(context) {
  10. const knownFragmentNames = Object.create(null);
  11. return {
  12. OperationDefinition: () => false,
  13. FragmentDefinition(node) {
  14. const fragmentName = node.name.value;
  15. if (knownFragmentNames[fragmentName]) {
  16. context.reportError(
  17. new GraphQLError(
  18. `There can be only one fragment named "${fragmentName}".`,
  19. {
  20. nodes: [knownFragmentNames[fragmentName], node.name],
  21. },
  22. ),
  23. );
  24. } else {
  25. knownFragmentNames[fragmentName] = node.name;
  26. }
  27. return false;
  28. },
  29. };
  30. }