Save data To MongoDB: Node.js

After learning to connect our Node.js application to MongoDB, lets see how we could insert data into our database collection.

insert-into-mongoDB-nodejs

Note:
Save() is a higher lever method. It checks to see if the object we’re inserting is already present in our collection, by checking the _id value we’re inserting. _id field(which is a primary key in MongoDB document)
– If there is no matching _id field in a document, it’ll call insert method and insert the data. And if the data being entered has no _id value, insert() method will create _id value for us, and insert the data into the collection.
– If _id matches to any document in our collection, it’ll use update() instead to update the previously present data with the new data entered by the user.

Form To Facilitate User To Enter Her Details ..or Registration Form
public/index.html

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
< !DOCTYPE html>
<html>
<head>
<title>Registration Form</title>
</head>
<body>
 <form action="/new" method="POST">
<label for="email">Email: </label>
  <input type="email" name="email" /><br />
<label for="name">Name: </label>
  <input type="text" name="name" /><br />
<label for="age">Age: </label>
  <input type="number" name="age" /><br />
 <input type="submit"/>
</form>
</body>
</html>

Here we have 3 input fields(for email, name and age) and a submit button. Since we’re posting these data to /new (in the action field of the form), we need to create /new route.

Route To Process User Entries
app.js

1
2
3
4
5
6
7
8
9
10
app.post('/new', function(req, res){
new user({
_id    : req.body.email,
name: req.body.name,
age   : req.body.age
}).save(function(err, doc){
if(err) res.json(err);
else    res.send('Successfully inserted!');
});
});

By using bodyParser() middleware, we get the data from the form, parse it and assign the values to corresponding keys, by creating a new user.

Note: user is a model object in our example. We also chain save method with new user object. Save() method takes a callback method as argument. The callback method takes 2 arguments – error and document. We check, if there are any errors while inserting the data, if so, we output the error object on to the screen. If the insertion was successful, we display “Successfully inserted!” message.

Inserting data To MongoDB: Node.js


[youtube https://www.youtube.com/watch?v=uZqwHfNIf8M]

YouTube Link: https://www.youtube.com/watch?v=uZqwHfNIf8M [Watch the Video In Full Screen.]



Related Read:
number Input Type: HTML5
Create and Insert Documents: MongoDB
MongoDB Tutorial List

Full Code
app.js

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
var express = require('express');
var http = require('http');
var path = require('path');
var mongoose = require('mongoose');
 
var app = express();
 
// all environments
app.set('port', process.env.PORT || 3000);
app.set('views', __dirname + '/views');
app.set('view engine', 'jade');
 
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(app.router);
app.use(express.static(path.join(__dirname, 'public')));
 
mongoose.connect('mongodb://localhost/Company');
 
var Schema = new mongoose.Schema({
_id    : String,
name: String,
age   : Number
});
 
var user = mongoose.model('emp', Schema);
 
app.post('/new', function(req, res){
new user({
_id    : req.body.email,
name: req.body.name,
age   : req.body.age
}).save(function(err, doc){
if(err) res.json(err);
else    res.send('Successfully inserted!');
});
});
 
 
 
var server = http.createServer(app).listen(app.get('port'), function(){
  console.log('Express server listening on port ' + app.get('port'));
});

Here we’ve shown the configurations, middleware, mongoose connection, schema, model object, routes and out application server.

Connecting To MongoDB Using Mongoose: Node.js

In today’s video tutorial lets learn to connect to MongoDB server from our Node.js application using Mongoose module.

node-mongoose-mongoDB

Mongoose Module
Mongoose provides a straight-forward, schema-based solution to modeling your application data and includes built-in type casting, validation, query building, business logic hooks and more..

MongoDB
MongoDB is one of the leading NoSQL database. Know more about it at MongoDB – Getting Started Guide

Related Read: MongoDB Tutorial List

Listing Mongoose As A Dependency
package.json

1
2
3
4
5
6
7
8
9
10
11
12
13
{
  "name": "application-name",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "nodemon app.js"
  },
  "dependencies": {
"express": "*",
"nodemon": "*",
"mongoose": "*"
  }
}

list the mongoose module as a dependency for your Node.js application

Install the dependencies

1
npm install

This looks for all the dependencies listed in package.json file and installs it. Make sure that your system is connected to the internet.

Connecting to MongoDB
app.js

1
2
3
4
5
6
7
8
9
10
11
12
13
14
var mongoose = require('mongoose');
 
app.use(express.bodyParser());
app.use(express.methodOverride());
 
mongoose.connect('mongodb://localhost/Company');
 
var mySchema = new mongoose.Schema({
_id    : String,
name: String,
age   : Number
});
 
var user = mongoose.model('emp', mySchema);

We have to first include mongoose module into our application. We also need the help of bodyParser() and methodOverride() middlewares in order to parse the form variables and override method to make PUT and DELETE methods work.

Next we connect to mongobd using connect method of mongoose module. Here we also specify the mongoDB database name to which our application will be connecting to. If the database is not already present, this will create one for us.

Next, we write a schema definition for our collection. Mongoose uses schema for validation of user entered data. By specifying the data type for our field we can make sure user entries are validated against the data types we have mentioned in our schema.

Some valid Schema Types, supported by Mongoose
String
Number
Date
Buffer
Boolean
Mixed
Objectid
Array

Mongoose Model
A model in mongoose is an object that gives us easy access to a named collection, allowing us to query the collection and use the schema to validate any document we save to that collection.

Connecting To MongoDB Using Mongoose: Node.js


[youtube https://www.youtube.com/watch?v=93APwwh35PA]

YouTube Link: https://www.youtube.com/watch?v=93APwwh35PA [Watch the Video In Full Screen.]



Note 1: In above example code, we are creating a collection called emp and binding it with the schema mySchema

In above example
Database name: Company
Collection/table name: emp

Note 2: Make sure MongoDB server is up and running, before you execute your Node.js application.

Checking If your application succesfully connected to MongoDB Server!
app.js

1
2
3
4
5
var db = mongoose.connection('mongodb://localhost/Company');
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function callback () {
  // all your database operations(CRUD) here 
});

Here by using on method we check if we could successfully connect to our mongoDB server. If there was any error, we output the error on to the screen. If the connection is successful, we’ll continue with our CRUD operations on the database tables.

DBMS Basics: Getting Started Guide

Getting started with Database Management System.

In this video tutorial we’re trying our best to keep everything to the minimum, and make sure not to make it look complicated for beginners.

The tables and the normalization shown in the video are just for the purpose of demonstration.

dbms-basics

DBMS is a software system which helps in managing incoming data, organizes it and provides certain ways for the data to be modified and/or extracted by the users or other programs.

Some examples of Database Management System Software include MySQL, PostgreSQL, Microsoft Access, SQL Server, FileMaker, Oracle, RDBMS, dBASE, Clipper, and FoxPro.
Also: Some Native database systems that can be connected with PHP ?

Tables Relational databases are made up of relations, commonly known as TABLES.
Relationships exists between the tables and the data are inter-related by making use of Primary and Foreign keys.

Table Columns
It has unique names.
Each column has an associated datatype.
Columns are sometimes called as fields or attributes.

Table Rows
Each row in the table represents individual data.
Rows are also called as records or tuples.

Values
Every value must have the same data type, as specified by it’s column.

Key
To identify each row uniquely.
The identifying column in a table is called as key or primary key.

Schema
Complete set of table design for a database.
It’s like a blueprint for the database.

A Schema should show the tables along with their columns, and the primary and foreign keys. Usually primary key’s are underlines and foreign keys are italicized.

Database Management System: Basics


[youtube https://www.youtube.com/watch?v=aR44FbeeFH8]

YouTube Link: https://www.youtube.com/watch?v=aR44FbeeFH8 [Watch the Video In Full Screen.]



Anomalies
Assume that we’re running an online store.
We’ve a order table.

If a person called Satish orders Apple iPad, Mac Book and a iPhone from our site.
We store his name and address and quantity of his order.

Next, Satish moves to a different place before we process the order, now we will need to update his address at 3 places!

Doing 3 times as much work. We may miss updating Satish’s address in some place, making the data inconsistent. This is called modification anomaly.

If we design our database table in this way, we’ll need to take the address of Satish each time he orders something from our online store. This way, we need to always make sure the address(data) is consistent across all the rows. If we do not take care, we may end up with conflicting data.
Ex: One row may indicate Satish to be living in Bangalore and another row may indicated Satish to be living in New York!
This scenario is called Insertion anomaly.

Once all the orders of Satish has been processed, we delete the records. This way, we no longer have Satish’s address. So we can’t send any promotional offers etc to Satish in the future. If he want’s to order something again from our online store, he need to enter his address again. This scenario is called deletion anomaly.

We could solve these anomaly problems by making use of Primary and Foreign key’s and by developing the skill/art of normalization.

Database normalization is the process of organizing the fields and tables of a relational database to minimize redundancy and dependency. Normalization usually involves dividing large tables into smaller (and less redundant) tables and defining relationships between them. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database using the defined relationships.

Primary Key
The PRIMARY KEY constraint uniquely identifies each record in a database table.
Primary keys must contain unique values.
A primary key column cannot contain NULL values.
Each table should have a primary key, and each table can have only ONE primary key.

Foreign Key
A foreign key is a field in a relational table that matches a candidate key of another table. The foreign key can be used to cross-reference tables.

Relationships
We’ll cover
one-one
one-many
many-many
relationships in coming video tutorials, with some real time examples.