Quick Startedit

Creating a clientedit

Start using Elasticsearch.js by creating an instance of the elasticsearch.Client class. The constructor accepts a config object/hash where you can define defaults values, or even entire classes, for the client to use. For a full list of config options check out the the section dedicated to configuration.

var elasticsearch = require('elasticsearch');
var client = new elasticsearch.Client({
  host: 'localhost:9200',
  log: 'trace'
});

Say hello to Elasticsearchedit

Almost all of the methods on the client accept two arguments:

  • params - an optional object/hash of parameters More info here.
  • callback - an optional function that will be called with the final result of the method. When omitted, a promise is returned. More info here.

Ping the clusteredit

Send a HEAD request to "/" and allow up to 30 seconds for it to complete. 

client.ping({
  requestTimeout: 30000,
}, function (error) {
  if (error) {
    console.error('elasticsearch cluster is down!');
  } else {
    console.log('All is well');
  }
});

Use Promisesedit

Skip the callback to get a promise back. 

client.search({
  q: 'pants'
}).then(function (body) {
  var hits = body.hits.hits;
}, function (error) {
  console.trace(error.message);
});

Allow 404 responsesedit

Prevent 404 responses from being considered errors by telling the client to ignore them. 

client.indices.delete({
  index: 'test_index',
  ignore: [404]
}).then(function (body) {
  // since we told the client to ignore 404 errors, the
  // promise is resolved even if the index does not exist
  console.log('index was deleted or never existed');
}, function (error) {
  // oh no!
});

Searching for documentsedit

A very common use-case for elasticsearch is to sort through large collections of documents in order to find ones that are relevant to a query. In most cases you will use the client’s search() method to accomplish this.

Elasticsearch Query DSLedit

For many searches you will want to define a search document that tells elasticsearch exactly how to find the documents you are looking for. To do this you will use the elasticsearch query DSL. If you are not familiar with Elasticsearch’s query DSL it is recommended that you research the topic at elasticsearch.org or watch/read one of these introductions:

Now for some examples using the Query DSL.

Simple match queryedit

Find tweets that have "elasticsearch" in their body field. 

client.search({
  index: 'twitter',
  type: 'tweets',
  body: {
    query: {
      match: {
        body: 'elasticsearch'
      }
    }
  }
}).then(function (resp) {
    var hits = resp.hits.hits;
}, function (err) {
    console.trace(err.message);
});

More complex filtered queryedit

To power a search form on a public site, you might want to allow the user to specify some text but also limit the documents returned by a few criteria. This is a good use-case for a filtered query.

Note

In this example, request and response are Express request and response objects.

var pageNum = request.params.page;
var perPage = request.params.per_page;
var userQuery = request.params.search_query;
var userId = request.session.userId;

var searchParams = {
  index: 'posts',
  from: (pageNum - 1) * perPage,
  size: perPage,
  body: {
    query: {
      filtered: {
        query: {
          match: {
            // match the query against all of
            // the fields in the posts index
            _all: userQuery
          }
        },
        filter: {
          // only return documents that are
          // public or owned by the current user
          or: [
            {
              term: { privacy: "public" }
            },
            {
              term: { owner: userId }
            }
          ]
        }
      }
    }
  }
};

client.search(searchParams, function (err, res) {
  if (err) {
    // handle error
    throw err;
  }

  response.render('search_results', {
    results: res.hits.hits,
    page: pageNum,
    pages: Math.ceil(res.hits.total / perPage)
  });
});

You can find a lot more information about filters here