graphql/validation/rules/LoneSchemaDefinitionRule.mjs

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

/**
 * Lone Schema definition
 *
 * A GraphQL document is only valid if it contains only one schema definition.
 */
export function LoneSchemaDefinitionRule(context) {
  var _ref, _ref2, _oldSchema$astNode;

  var oldSchema = context.getSchema();
  var alreadyDefined = (_ref = (_ref2 = (_oldSchema$astNode = oldSchema === null || oldSchema === void 0 ? void 0 : oldSchema.astNode) !== null && _oldSchema$astNode !== void 0 ? _oldSchema$astNode : oldSchema === null || oldSchema === void 0 ? void 0 : oldSchema.getQueryType()) !== null && _ref2 !== void 0 ? _ref2 : oldSchema === null || oldSchema === void 0 ? void 0 : oldSchema.getMutationType()) !== null && _ref !== void 0 ? _ref : oldSchema === null || oldSchema === void 0 ? void 0 : oldSchema.getSubscriptionType();
  var schemaDefinitionsCount = 0;
  return {
    SchemaDefinition: function SchemaDefinition(node) {
      if (alreadyDefined) {
        context.reportError(new GraphQLError('Cannot define a new schema within a schema extension.', node));
        return;
      }

      if (schemaDefinitionsCount > 0) {
        context.reportError(new GraphQLError('Must provide only one schema definition.', node));
      }

      ++schemaDefinitionsCount;
    }
  };
}