graphql/validation/rules/UniqueDirectiveNamesRule.mjs

import { GraphQLError } from "../../error/GraphQLError.mjs";

/**
 * Unique directive names
 *
 * A GraphQL document is only valid if all defined directives have unique names.
 */
export function UniqueDirectiveNamesRule(context) {
  var knownDirectiveNames = Object.create(null);
  var schema = context.getSchema();
  return {
    DirectiveDefinition: function DirectiveDefinition(node) {
      var directiveName = node.name.value;

      if (schema !== null && schema !== void 0 && schema.getDirective(directiveName)) {
        context.reportError(new GraphQLError("Directive \"@".concat(directiveName, "\" already exists in the schema. It cannot be redefined."), node.name));
        return;
      }

      if (knownDirectiveNames[directiveName]) {
        context.reportError(new GraphQLError("There can be only one directive named \"@".concat(directiveName, "\"."), [knownDirectiveNames[directiveName], node.name]));
      } else {
        knownDirectiveNames[directiveName] = node.name;
      }

      return false;
    }
  };
}