getPostsFromUser: function( req, res ){

    //the beginning is pretty much the same as before
    var userName = req.param('username');

    User.findOneByName(userName)
      .populate('posts')
      .then(function (user) {
        if (!user) return res.notFound();

        var posts = user.posts,
            postIds = [];

        //we have to avoid looping over an async function
        //therefore we first have to collect all post ids...
        posts.forEach(function(post){
          postIds.push(post.id);
        });

        //... to be able to find all comments we need with just one db query
        var comments = Comment.find({post: postIds})
          .then(function(comments){
            return comments;
          });

        //with bluebird this array...
        return [user, comments];

      })
      //... will be passed here as soon as the comments are finished loading
      .spread(function(user, comments){

        //now we have our user object with all posts and an array with all the comments...
        user.posts.forEach(function(post){
          //... which means we have to attach comments to posts manually
          post.attachedComments = comments.filter(function(comment){
            return comment.post == post.id;
          });
        });

        //then we can return our user object
        return res.json(user);

      })
      .fail(function(error){
        sails.log.error(error);
        return res.negotiate(error);
      });

  }