stitching-service.js

const serviceStitching = function (mergeInfo) {
  return {
    Service: {
      category: {
        fragment: 'fragment CategoryTypeFragment on Category { slug }',
        resolve(parent, args, context, info) {
          return mergeInfo.delegate(
            'query',
            'category',
            { slug: parent.categorySlug },
            context,
            info,
          );
        },
      },
    },
  };
};

export default serviceStitching;