angularNodeMongoPoki

Simple introduction to attaching a mongo database to a angular-node project

We will start with a simple angular application that talks to a node back end. We went through this tutorial before, but you may want to clone this repository to get started

git clone https://github.com/mjcleme/angularNodeMongoPoki
cd angularNodeMongoPoki
npm install
npm start

And make sure the application displays pokemon defined in the routes/index.js back end.

Connecting to MongoDB

1. Get access to MongoDB in our javascript

We will need to use npm here to install the javascript library that helps us communicate with mongodb.

npm install --save mongodb

Now, add the module to your routes/index.js file

var mongodb = require('mongodb');

2. Open a connection

Next we will open a connection to mongodb using our snazzy new javascript library. Feel free to paste the following right underneath where we declare the mongodb variable.

// We need to work with "MongoClient" interface in order to connect to a mongodb server.
var MongoClient = mongodb.MongoClient;

// Connection URL. This is where your mongodb server is running.
var dbUrl = 'mongodb://localhost:27017/';

// we will use this variable later to insert and retrieve a "collection" of data
var collection

// Use connect method to connect to the Server
MongoClient.connect(dbUrl, { useNewUrlParser: true }, function(err, client) {
  if (err) {
    console.log('Unable to connect to the mongoDB server. Error:', err);
  }
  else {
    // HURRAY!! We are connected. :)
    console.log('Connection established to', dbUrl);
    
    /**
     * TODO: insert data here, once we've successfully connected
     */
  }
});

Go ahead and run npm start in your terminal again, and you should expect to see the connection established log.

Inserting data

1. Make a 'pokemon' collection

Let's put that collection variable we already declared to work. Notice that in the callback function we provided to MongoClient.connect, we expect to receive a client variable. We will use that to select the pokemon database and then create a poke collection like so:

    var db = client.db('pokemon'); //Connect to the database pokemon
    db.createCollection('poke', function(err, result) { // If it exists, it will just connect to it
      collection = result;
      // Do something with the collection here
    }); // Get the collection

2. Insert data

Now we will use that collection object to insert the array pokemon like so:

      // Only do the insert if the collection is empty
      collection.stats(function(err, stats) {
        if (err) { console.log(err) }
        if (stats.count == 0) { // If we havent inserted before, put the default in
          collection.insertMany(pokemon, function(err, result) {
            if (err) { console.log(err) }
            else {
              console.log('Inserted documents into the "poke" collection. The documents inserted with "_id" are:', result.length, result);
            }
          });
        }
      });

All said and done our code connecting to the db and inserting our array of pokemon into the database should look something like the following:

// Use connect method to connect to the Server
MongoClient.connect(dbUrl, { useNewUrlParser: true }, function(err, client) {
  if (err) {
    console.log('Unable to connect to the mongoDB server. Error:', err);
  }
  else {
    // HURRAY!! We are connected. :)
    console.log('Connection established to', dbUrl);
    // do some work here with the database.
    var db = client.db('pokemon'); //Connect to the database
    db.createCollection('poke', function(err, result) {
      collection = result;

      collection.stats(function(err, stats) {
        if (err) { console.log(err) }
        if (stats.count == 0) { // If we havent inserted before, put the default in
          collection.insertMany(pokemon, function(err, result) {
            if (err) { console.log(err) }
            else {
              console.log('Inserted documents into the "poke" collection. The documents inserted with "_id" are:', result.length, result);
            }
          });
        }
      });
    }); // Get the collection
  }
});

If we run npm start we should expect a log telling us we have an established connection, and a log informing us we've inserted documents.

Retrieving data

Now we need to have our get route use data from the database.

The current code just returns the pokimon array

router.get('/pokemon', function(req, res) {
  console.log("In Pokemon");
  res.send(pokemon);
});

Replace it with a call to query the database

router.get('/pokemon', function(req, res) {
  console.log("In Pokemon");
  collection.find().toArray(function(err, result) {
    if (err) { console.log(err); }
    else if (result.length) {
      console.log("Query Worked");
      console.log(result);
      res.send(result);
    }
    else {
      console.log("No Documents found");
    }
  });
});

Now we just need to modify the post to put the new pokemon from the form into the database. We will replace

router.post('/pokemon', function(req, res) {
    console.log("In Pokemon Post");
    console.log(req.body);
    pokemon.push(req.body);
    res.end('{"success" : "Updated Successfully", "status" : 200}');
});

with

router.post('/pokemon', function(req, res) {
  console.log("In Pokemon Post");
  collection.insertOne(req.body, function(err, result) {
    if (err) {
      console.log(err);
    }
    else {
      console.log('Inserted document into the "pokemon" collection.');
      res.end('{"success" : "Updated Successfully", "status" : 200}');
    }
  });
});