const resolvers = {
  Query: {
    async feed(parent, { authorId }, ctx, info) {
      // build filter
      const authorFilter = authorId ? { author: { id: authorId } } : {}

      // retrieve (potentially filtered) posts
      const posts = await ctx.db.query.posts({ where: authorFilter })

      // retrieve (potentially filtered) element count
      const postsConnection = await ctx.db.query.postsConnection(
        { where: authorFilter },
        `{ aggregate { count } }`,
      )
      return {
        count: postsConnection.aggregate.count,
        posts: posts,
      }
    },
  },
}