How to create a json string with a list of hits._source using NodeJs and ElastiSearch

Question

I am strugling for two or three days locking for a very simple task: get the result of search and fill in a model. I have done this task many time with MongoDb but I am complety stuck with ElasticSearch and I am sure it must exist some easy way to do but I can't find a north. I have read a lot around but I am really stuck.

I can see the result of search. If someone at least tell me how to take away _index, _type, _id and _score and return just the _source as an array it may be useful.

I understand, as far as I can see, that ElasticSearch was designed with speed in mind so _score is part of the reason to use ElasticSearch. In my case, I must use only ElasticSearch in our server because they allow ElasticSearch in such server and ElasticSearch is already used for LogStash and Kibana. I am very happy with such challenge and I have been learning a lot about ElasticSearch but I do need some north about "serialize/desearile" the _source content in order move forward.

I put my entire code bellow. I guess that there may exist a clue using Schema and mongoosastic but I am really without ideas what to try.

You can see I created a model with schema and I added the plugin mongoosastic. I guess it might exist some way to use such model with ElasticSearch similar as we easily do with MOngoDb but I don't know how.

Server.js

var express = require('express');
var mongoose = require('mongoose');
var bodyParser = require('body-parser');

var esController = require('./controllers/mycontroller');

mongoose.connect('mongodb://localhost:27017/greencard');

var app = express();

var router = express.Router();

router.route('/myexposedmethod')
  .get(esController.myexposedmethod);
app.use('/api', router);

app.listen(3000);

package.json

{
  "name": "greencard-dmz-es-oracle",
  "main": "server.js",
  "dependencies": {
    "elasticsearch": "^12.1.3",
    "express": "^4.1.1",
    "express-session": "^1.6.1",
    "mongoosastic": "^4.2.4",
    "mongoose": "^3.8.8",
    "reqclient": "^2.1.0"
  }
}

mycontroller.js

var elasticsearch = require('elasticsearch');
var Promise = require('bluebird');
var Mymodel = require('../models/mymodel');

var query = {
    "bool": {
        "must": {
            "term": { "my_prop1": "my" }
        }
    }
}

exports.myexposedmethod = function (req, res) {

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

    function closeConnection() {
        client.close();
    }

    function createIndex() {
        return client.indices.create({
            index: "myindex",
            body: {
                "mappings": {
                    "my_type": {
                        "properties": {

                            "my_prop1": { "type": "string" }
                        }
                    }
                }
            }
        }

        );
    }

    function addToIndex() {
        return client.index({
            index: 'myindex',
            type: 'my_type',
            body: {

                my_prop1: 'my second string to be inserted'

            },
            refresh: true
        });
    }

    function search() {
        return client.search({
            index: 'myindex',
            type: 'my_type',

            body: {
                query: {
                    match: {
                        my_prop1: {
                            query: 'my'
                        }
                    }
                }
            }
        }).then(function (resp) {
            var hits = resp.hits.hits;

            console.log(hits.length);

            hits.forEach(function (hit) {
                console.log("_source: ", hit._source);
            })

            //I know it is not going to work but may express what I am locking for
            //var mymodel_result = JSON.stringify({
            //    mymodel: hits._source
            //});
 //the return to http://localhost:3000/api/myexposedmethod is
 /*[           
  {
    "_index": "myindex",
    "_type": "my_type",
    "_id": "AVpmQ4GbDU4zGDgLLeeR",
    "_score": 0.16948202,
    "_source": {
      "my_prop1": "my first string to be inserted"
    }
  },
  {
    "_index": "myindex",
    "_type": "my_type",
    "_id": "AVpmXus8DU4zGDgLLeeU",
    "_score": 0.16948202,
    "_source": {
      "my_prop1": "my second string to be inserted"
    }
  }
]*/
//but I want something like
//[{"my_prop1": "my first string to be inserted"},{"my_prop1": "my second string to be inserted"}]
//or
//[{"mymodel": "my first string to be inserted"},{"mymodel": "my second string to be inserted"}]


            return res.json(hits);

        }, function (err) {
            console.trace(err.message);
        });
    }

    Promise.resolve()
        //.then(createIndex)
        //.then(addToIndex)
        .then(search)
        .then(closeConnection)
        ;

};

mymodel.js inspirid in how I use to work with MongoDb plus mongooastic

var mongoose = require('mongoose'),
    mongoosastic = require('mongoosastic'),
    Schema = mongoose.Schema

var myschema = new Schema(
    { my_prop1: String }
)

myschema.plugin(mongoosastic)

Answer 1

You just have to map the resp.hits.hits array to an array formatted to your liking.

var newArray = resp.hits.hits.map(function(hit) {
 return hit._source;
});

newArray will contain all the _source field from the resp.hits.hits array, so it will look like this:

[{"my_prop1": "my first string to be inserted"},{"my_prop1": "my second string to be inserted"}]