Indexing documents to Elasticsearch

In src/index.js, import the Elasticsearch library and initiate a client as we did before; then, in the request handler for POST /users, use the Elasticsearch JavaScript client's index method to add the payload object into the Elasticsearch index:

import elasticsearch from 'elasticsearch';
const client = new elasticsearch.Client({
  host: `${process.env.ELASTICSEARCH_PROTOCOL}://${process.env.ELASTICSEARCH_HOSTNAME}:${process.env.ELASTICSEARCH_PORT}`,
});
...

app.post('/users', (req, res, next) => {
  ...
  client.index({
    index: 'hobnob',
    type: 'user',
    body: req.body
  })
}

The index method returns a promise, which should resolve to something similar to this:

{ _index: 'hobnob',
  _type: 'users',
  _id: 'AV7HyAlRmIBlG9P7rgWY',
  _version: 1,
  result: 'created',
  _shards: { total: 2, successful: 1, failed: 0 },
  created: true }

The only useful and relevant piece of information we can return to the client is the newly auto-generated _id field. Therefore, we should extract that information and make the function return a promise, which resolves to only the _id field value. As a last resort, return a 500 Internal Server error to indicate to the client that their request is valid, but our server is experiencing some issues:

client.index({
  index: 'hobnob',
  type: 'user',
  body: req.body,
}).then((result) => {
  res.status(201);
  res.set('Content-Type', 'text/plain');
  res.send(result._id);
}).catch(() => {
  res.status(500);
  res.set('Content-Type', 'application/json');
  res.json({ message: 'Internal Server Error' });
});

Now, our E2E tests should all pass again!