Elasticsearch show only the name of all indices with node js

Question

I am using ejs framework with node js. I can get all the index names in json format. But what I want is just the names of the indices. My code looks like as follows-

var client = require('../routes/Connection.js');

//display all indexes
module.exports.allIndexes = function (searchData, callback) {
    client.indices.getAliases({
        index: "_all",
        level: "indices"
    }, function (error, response, status) {
        if (error) {
            console.log("search error: " + error)
        }
        else {
            //callback(response);---> this works
            callback(response.hits.hits); // ---> this doesn't
        }
    });
}

if I use response in callback, I get the following output:

{
  "index-1": {
    "aliases": {}
  },
  "index-2": {
    "aliases": {}
  },
  "index-3": {
    "aliases": {}
  },
  "index-4": {
    "aliases": {}
  }
}

and when I use response.hits.hits in callback I get the error:"cannot read property 'hits' of undefined". I want to show only the index names as a list. FYI, in front end, I passed the response say as "results" :

        <h1>Index</h1>
        <% for(var i=0; i < results.length; i++) { %>
          <%= results[i].indices %>
        <% } %>

which shows nothing ofcourse.

edit_1:

I import the module as follows: in my index.js :

router.post('/indexes', function (req, res) {
    elasticModule.allIndexes(req.body, function (data) {
        res.render('elasticGui', { title: 'Elasticsearch GUI', results: data });
    });
});

Answer 1

When looking at your response structure

{
  "index-1": {
    "aliases": {}
  },
  "index-2": {
    "aliases": {}
  },
  "index-3": {
    "aliases": {}
  },
  "index-4": {
    "aliases": {}
  }
}

you don't see any hits , do you? So response.hits is undefined and the error happens when trying to reference hits out of response.hits

You simply need to change your code like this:

callback(Object.keys(response));

And then in your view you can iterate over that array like this:

    <% results.forEach(function(index) { %>
      <%= index %>
    <% }); %>