Horea's Blog

Trying to update your Cloudant Database via REST API? Not sure how to get started? You’ve come to the right place. In this post, I’ll teach you how to update your database programmatically using Node.js and REST API calls. As a bonus, I’ll show you how to keep track of the objects in your database, and how to sort your database according to your most popular objects.

I will assume you have created a Cloudant account through IBM Cloud “Bluemix”, and have created a database and a document through the Cloudant UI. (There is a create database and create document button at the top-right corner of Cloudant Website.) Now let’s get to the fun part.

Getting the Current State of our Database

The first thing we want to do is make a simple ‘GET’ request to get the current state of our database. To setup our GET request, we need to provide our authentication and Cloudant URL. This should look something like this: P.S (The below username and password do NOT work, they are simply for learning purposes.)

var auth = 'Basic ' + new Buffer("https://8bb71405-438f-4372-9b43-975e0220f3cd-bluemix" +
':' +"935624a91478c5f8918d3d0b2e104ef6fe825939ed2304f28ec2225fa9a952df").toString('base64');

var options = {
  url: https://8bb71405-438f-4372-9b43-975e0220f3cd-bluemix.cloudant.com/db1/1e37764c1dfc4d448bc2450e9c04ecd0,
  method: 'GET',
  headers: {
      'Authorization': auth;
  }
};

The first thing to note is the URL. The first part of the URL is simply your username - it ends with ‘-bluemix.cloudant.com’. The next part of the URL is your specific database. In my case, I named my database ‘db1’. The last part of the URL is the specific document in that database. The document that I created in ‘db1’ has an ‘id’ of “1e37764c1dfc4d448bc2450e9c04ecd0”. Next, your authentication. The first part of the authentication header is your Cloudant Username - the first part of the URL. The second (and last) part of the authentication is simply your Cloudant Password. Now, let’s use the request package (if you don’t have it, you can simply do an npm install request) to make the GET call.

request.get(options, function(err, body){
  if (err) {
    console.log(err);
  }
  var docObj = JSON.parse(body.body)
  var revID = docObj._rev;
}

Inserting into Cloudant

The most important part of the request body is the Revision ID or ‘._rev’. This is a number that Cloudant assigns to keep track of the number of times you have updated your specific document. We need this number to update our database. Now that we have the revision ID number, we can use that to update the same document over and over. To insert into our database, we will simply make a PUT request and use the revID that we got from the GET request to ensure that we will update our current document. As an example, I simply inserted a tennis player into the database.

request.get(options, function(err, body){
  var docObj = JSON.parse(body.body)
  var revID = docObj._rev;
  var tennisPlayers = {name:'Andre Agassi'}

  var putOptions = {
    url: https://8bb71405-438f-4372-9b43-975e0220f3cd-bluemix.cloudant.com/db1/1e37764c1dfc4d448bc2450e9c04ecd0,
    method: 'PUT',
    json: {
      '_rev': revID,
      'index':tennisPlayers //where all of our data goes
    },
    headers: {
        'Authorization': auth,
        'Content-Type': 'application/json' //needed since we are inserting json
    }
  };

  request.put(putOptions, function(err, body){
    console.log(body) //should give you a message saying that you have successfully inserted
  });
}

Bonus: Sorting Database by Relevance

In this last section, i’ll show you how to sort your database by relevance using a simple sort function. Let’s say you want to sort a database of tennis players by the number of grand slams they win. Let’s say you want to update after every Grand Slam.

var grandSlamWinners = [
  {name:'Rafael Nadal',grandSlams:'15'},
  {name:'Andre Agassi',grandSlams:'8'},
  {name:'Roger Federer',grandSlams:'19'}
]

Let’s suppose Roger Federer wins the 2017 US Open…which would be a ‘joke’ as quoted by Federer himself. Then we would want to increment the number of slams he has. Thus, we need to search through the database to see if the player has already won a slam, and if he has, then we want to increment his number of slams. Otherwise, its their first slam and we insert and them with their first Grand Slam. P.S. (You will probably want to do a check if the database is empty, and if it is, insert anyway, but this is beside the point).

var tennisPlayerToInsert = {name:'Roger Federer'}
var insertIntoDict = true;

  //check every player in the database for a match
  for(var i=0;i<grandSlamWinners.length;i++){
     if (grandSlamWinners[i].name == tennisPlayerToInsert.name) {
       insertIntoDict=false;
       grandSlamWinners[i].grandSlams++;
       break;
     }
  }
  //if player is not in DB, add it!
  if(insertIntoDict){
    grandSlamWinners.push({
      name: tennisPlayerToInsert.name,
      grandSlams: 1
    });
  }

First we check every single player in database to check if the US Open Slam Winner is a past winner. If they are, we set the flag to false, and increment their slam number. Otherwise, congrats on their first slam! One more bit…let’s sort by descending slams, since we want to see the most famous players first.

grandSlamWinners.sort(function(a, b) {
  return (b.grandSlams) - (a.grandSlams);
});

And that’s it! Hope you learned a bit more about Cloudant and databases in general.