Elasticsearch pagination with MongoDB and ExpressJS

Question

I tried to search online for a solution but to be honest I still didn't found anything that help me to achieve this.

It is the first time I use ElasticSearch and I'm also pretty new with Node and MongoDB.

So, I followed a kind of tutorial and implemented Mongooastic from NPM to let ElasticSearch work with Node.

It seems to work fine even if on a total of 12 users indexed, if I type in the search "user" in the search list view I can find 12 records, it show 10 in a for each and the first one has missing values...

But the main problem for me is the pagination... or a sort of... it will be also nice to implement infinite scroll on it but I don't really know how to handle it.

So, the controller that handle it is the following at the moment:

exports.searchUsers = function(req, res) {
    User.search({
      query_string: {
        query: req.query.q
      }
    },
    { hydrate: true },
    function(err, results) {
      if (err) res.send(err);
      res.render('search-results', {
        results: results,
        users: results.hits.hits
      });
    });
};

I don't really know where to put size and from in here... and after understanding this I also would like to know how to implement, if possible, a sort of infinite scroll... And also how to handle link for the pagination... ie: prev, 1, 2, 3, 4, ..., next

The view has a simple input text for the search, after pressing submit it open a new page with the list of hits , so it should be nothing complex...

I hope you may help. Thanks

Answer 1

By default elasticsearch returns the 10 first results: you will have to set the size parameter if you want more.

Also, in order to add the size and from parameters, you need to write your query like so:

User.search({
    query: {
      query_string: {
        query: req.query.q
      }
    },
    size: 30,
    from: 30
  },
  {hydrate: true},
  function (err, results) {
    if (err) res.send(err);
    res.render('search-results', {
      results: results,
      users: results.hits.hits
    });
  });

(see here: https://github.com/taterbase/mongoosastic/issues/123 )

This will give you user n°30 up to user n°60 (more info here: http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-request-from-size.html ). You will have to play with your frontend to get the values you want for your size and from parameters.