Author: Satish

$exists, $type, $regex operators: MongoDB

In today’s video tutorial, lets learn to use $exists, $type and $regex operators.

mongodb-exisits-type-regex

Documents in our collection
test database, names collection.

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> use test
switched to db test
> show collections
names
system.indexes
 
> db.names.find().pretty()
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }
{ "_id" : ObjectId("53be5d8604cc1cb0a7bfc3c5"), "name" : "Farhan" }
{ "_id" : ObjectId("53be5d9204cc1cb0a7bfc3c6"), "name" : "Gangs" }
{ "_id" : ObjectId("53be5d9904cc1cb0a7bfc3c7"), "name" : "Hum" }
{ "_id" : ObjectId("53be5e3704cc1cb0a7bfc3c8"), "name" : 25 }
 
> db.names.insert({"name": "Satish", "age": 27});
WriteResult({ "nInserted" : 1 })
 
 
> db.names.find().pretty()
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }
{ "_id" : ObjectId("53be5d8604cc1cb0a7bfc3c5"), "name" : "Farhan" }
{ "_id" : ObjectId("53be5d9204cc1cb0a7bfc3c6"), "name" : "Gangs" }
{ "_id" : ObjectId("53be5d9904cc1cb0a7bfc3c7"), "name" : "Hum" }
{ "_id" : ObjectId("53be5e3704cc1cb0a7bfc3c8"), "name" : 25 }
{
        "_id" : ObjectId("53beaa0f6a8a31dc255d4589"),
        "name" : "Satish",
        "age" : 27
}

Observe the documents – it has some names which are in alphabetical order. Last document has an extra field called age. And another odd entry is a document with name as 25.

$exists take 2 values, true or false

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> db.names.find({"age": {$exists: true}});
{ "_id" : ObjectId("53beaa0f6a8a31dc255d4589"), "name" : "Satish", "age" : 27 }
 
> db.names.find({"age": {$exists: false}});
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }
{ "_id" : ObjectId("53be5d8604cc1cb0a7bfc3c5"), "name" : "Farhan" }
{ "_id" : ObjectId("53be5d9204cc1cb0a7bfc3c6"), "name" : "Gangs" }
{ "_id" : ObjectId("53be5d9904cc1cb0a7bfc3c7"), "name" : "Hum" }
{ "_id" : ObjectId("53be5e3704cc1cb0a7bfc3c8"), "name" : 25 }

If $exists is true, it retrieves documents which has the specified field. If $exists is false, then it retrieves all the documents which do not have the specified field.

$exists, $type, $regex operators: MongoDB


[youtube https://www.youtube.com/watch?v=kAU4egwsBYo]

YouTube Link: https://www.youtube.com/watch?v=kAU4egwsBYo [Watch the Video In Full Screen.]



$type take numeric value(BSON specification)

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> db.names.find({"name": {$type: 1}});
{ "_id" : ObjectId("53be5e3704cc1cb0a7bfc3c8"), "name" : 25 }
 
> db.names.find({"name": {$type: 2}});
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }
{ "_id" : ObjectId("53be5d8604cc1cb0a7bfc3c5"), "name" : "Farhan" }
{ "_id" : ObjectId("53be5d9204cc1cb0a7bfc3c6"), "name" : "Gangs" }
{ "_id" : ObjectId("53be5d9904cc1cb0a7bfc3c7"), "name" : "Hum" }
{ "_id" : ObjectId("53beaa0f6a8a31dc255d4589"), "name" : "Satish", "age" : 27 }
TypeNumber
Double1
String2
Object3
Array4
Binary data5
Undefined6
Object id7
Boolean8
Date9
Null10
Regular Expression11
JavaScript13
Symbol14
JavaScript (with scope)15
32-bit integer16
Timestamp17
64-bit integer18
Min key255
Max key127

$regex (similar to perl regular expression)

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> db.names.find({"name": {$regex: "e"}});
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
 
> db.names.find({"name": {$regex: "^E"}});
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }
 
> db.names.find({"name": {$regex: "h$"}});
{ "_id" : ObjectId("53beaa0f6a8a31dc255d4589"), "name" : "Satish", "age" : 27 }
 
> db.names.find({"name": {$regex: "^[A-Z]"}});
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }
{ "_id" : ObjectId("53be5d8604cc1cb0a7bfc3c5"), "name" : "Farhan" }
{ "_id" : ObjectId("53be5d9204cc1cb0a7bfc3c6"), "name" : "Gangs" }
{ "_id" : ObjectId("53be5d9904cc1cb0a7bfc3c7"), "name" : "Hum" }
{ "_id" : ObjectId("53beaa0f6a8a31dc255d4589"), "name" : "Satish", "age" : 27 }
 
> db.names.find({"name": {$regex: "^[A-E]"}});
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }

$regex: “e” retrieves all the documents in which small letter “e” is present.
$regex: “^E” retrieves all the documents which has it’s name beginning letter as “E”.
$regex: “h$” retrieves all the documents which has it’s name ending letter as “h”.
$regex: “^[A-Z]” retrieves all the documents which has it’s name starting with characters “A” to “Z”.
$regex: “^[A-E]” retrieves all the documents which has it’s name starting with characters “A” to “E”.

Note: There is more to regular expression, this video is just an introduction. We’ll cover more about regular expressions in a separate video of it’s own.

String Comparison: MongoDB

Today we shall see how we can compare strings using comparison operators like,
$ne – not equal to
$gt – greater than
$gte – greater than or equal to
$lt – less than
$lte – less than or equal to

(In our video we have clearly illustrated the use of $lt and $gt. Your task is to understand it and try other comparison operators, and you can share your results in the comment section below.)

red apple green apple Comparison Operators: MongoDB

Related Read: Comparison Operators: MongoDB

Documents in our collection
test database, names collection.

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> db.names.find().pretty()
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }
{ "_id" : ObjectId("53be5d8604cc1cb0a7bfc3c5"), "name" : "Farhan" }
{ "_id" : ObjectId("53be5d9204cc1cb0a7bfc3c6"), "name" : "Gangs" }
{ "_id" : ObjectId("53be5d9904cc1cb0a7bfc3c7"), "name" : "Hum" }
{ "_id" : ObjectId("53be5e3704cc1cb0a7bfc3c8"), "name" : 25 }

Here we have names in alphabetical order, and an odd name with numeric value 25.

We’ll query the collection using $lt operator.

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> db.names.find({"name": {$lt: "C"}});
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }

It prints all strings which are lexicographically less than the capital letter “C”.

We’ll query the collection using $lt and $gt operator.

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> db.names.find({"name": {$lt: "F", $gt: "C"}});
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }

This outputs strings which are greater than character “C” and less than character “F”.

Here we check for names/strings which are less than character “C” as well as greater than character “C”.

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> db.names.find({"name": {$lt: "C"}});
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
 
 
> db.names.find({"name": {$gt: "C"}});
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }
{ "_id" : ObjectId("53be5d8604cc1cb0a7bfc3c5"), "name" : "Farhan" }
{ "_id" : ObjectId("53be5d9204cc1cb0a7bfc3c6"), "name" : "Gangs" }
{ "_id" : ObjectId("53be5d9904cc1cb0a7bfc3c7"), "name" : "Hum" }
>

But in both cases the entry with name as 25 doesn’t appear. This concludes that, in MongoDB while we compare string/character using comparison operator, the comparison occurs only between strings and character and not with other datatypes.

Comparison Operators on Strings: MongoDB


[youtube https://www.youtube.com/watch?v=Ts2canvhQCY]

YouTube Link: https://www.youtube.com/watch?v=Ts2canvhQCY [Watch the Video In Full Screen.]



Note:
Lexicographical order: In mathematics, the lexicographic or lexicographical order is a generalization of the way the alphabetical order of words is based on the alphabetical order of their component letters.

Remove / Delete Data From MongoDB: Node.js

Today lets learn how to delete documents from MongoDB collection via your node.js application.

remove-delete-data-mongoDB-nodejs

In this video tutorial, I’ll show you how to make use of normal app.get to delete data and also the use of app.delete to accomplish the same.

Related Read:
Connecting To MongoDB Using Mongoose: Node.js
Save data To MongoDB: Node.js
Fetch Data From MongoDB: Node.js
Fetch Individual User Data From MongoDB: Node.js
Update / Edit Data In MongoDB: Node.js
..please go through these tutorials before proceeding further. It’ll take less than 20 min

Adding Delete link
view/show.jade

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<h1>#{user.name}</h1>
ul
 li Age: #{user.age}
 li Email: #{user._id}
 
ul
 li 
  a(href="/user/#{user._id}/delete") Delete

This adds Delete link below each individual user information.

Delete Routes: remove()
app.js

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var user = mongoose.model('emp', Schema);
 
app.get('/user/:id/delete', function(req, res){
user.remove({_id: req.params.id}, 
   function(err){
if(err) res.json(err);
else    res.redirect('/view');
});
});

Here we simply make use of app.get and the route we are defining is /user/:id/delete Once the user clicks on the delete link with the user id in it, the route gets triggered and by using remove() method upon user object, we fetch the user data with the particular id that the user passed in from the URL and delete it from our mongoDB collection.

Delete Routes: findByIdAndRemove()
app.js

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var user = mongoose.model('emp', Schema);
 
app.get('/user/:id/delete', function(req, res){
user.findByIdAndRemove({_id: req.params.id}, 
   function(err, docs){
if(err) res.json(err);
else    res.redirect('/view');
});
});

Here we are using findByIdAndRemove() method of mongoose module to find the requested user and delete the user document. Syntax is same as remove() method, only change is, findByIdAndRemove() method also returns result object to the callback method along with error object.

app.delete
view/show.jade

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<h1>#{user.name}</h1>
ul
 li Age: #{user.age}
 li Email: #{user._id}
 
ul
 li 
  a(href="/user/#{user._id}/edit") Edit
 li
  form(action="/user/#{user._id}", method="POST")
   input(type="hidden", name="_method", value="DELETE")
   button(type="submit") Delete

Here we replace the delete link with a delete button. Here the action field value is /user/#{user._id} and the method used is POST. But we are also passing a hidden input field which overrides the method from POST to DELETE inside our node application.

Delete Routes: app.delete() and findByIdAndRemove()
app.js

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var user = mongoose.model('emp', Schema);
 
app.delete('/user/:id', function(req, res){
user.findByIdAndRemove({_id: req.params.id}, 
   function(err, docs){
if(err) res.json(err);
else    res.redirect('/view');
});
});

The findByIdAndRemove() method works the same way as explained above.

Delete Routes: app.delete() and remove()
app.js

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var user = mongoose.model('emp', Schema);
 
app.delete('/user/:id', function(req, res){
user.remove({_id: req.params.id}, 
   function(err){
if(err) res.json(err);
else    res.redirect('/view');
});
});

The remove() method works the same way as explained above.

Remove / Delete Data From MongoDB: Node.js


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

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



Full Source Code

new user registration form
public/index.html

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< !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>

Link to all registered users
view/index.jade

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ul
each user in users
 li
  a(href='/user/#{user._id}') #{user.name}

Edit form
view/edit-form.jade

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<h1>Editing #{user.name}'s profile!</h1>
form(method="POST", action="/user/#{user._id}")
 input(type="hidden", name="_method", value="PUT")
 p Name:
  input(type="text", name="name", value="#{user.name}")
 p Age:
  input(type="number", name="age", value="#{user.age}")
 p
  input(type="submit")

Show Individual User Information
view/show.jade

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<h1>#{user.name}</h1>
ul
 li Age: #{user.age}
 li Email: #{user._id}
 
ul
 li 
  a(href="/user/#{user._id}/edit") Edit
 li
  form(action="/user/#{user._id}", method="POST")
   input(type="hidden", name="_method", value="DELETE")
   button(type="submit") Delete

Main Node.js Application File, with Create, Read, Update and Delete Routes
app.js

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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.delete('/user/:id', function(req, res){
user.findByIdAndRemove({_id: req.params.id}, 
   function(err, docs){
if(err) res.json(err);
else    res.redirect('/view');
});
});
 
app.get('/user/:id/edit', function(req, res){
res.render('edit-form', {user: req.userId});
});
 
app.put('/user/:id', function(req, res){
user.findByIdAndUpdate({_id: req.params.id},
                   {
     name: req.body.name,
  age   : req.body.age
   }, function(err, docs){
 if(err) res.json(err);
else
{ 
   console.log(docs);
   res.redirect('/user/'+req.params.id);
 }
 });
});
 
app.param('id', function(req, res, next, id){
user.findById(id, function(err, docs){
if(err) res.json(err);
else
{
req.userId = docs;
next();
}
});
});
 
 
app.get('/user/:id', function(req, res){
res.render('show', {user: req.userId});
});
 
app.get('/view', function(req, res){
user.find({}, function(err, docs){
if(err) res.json(err);
else    res.render('index', {users: docs})
});
});
 
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.redirect('/view');
});
});
 
 
var server = http.createServer(app).listen(app.get('port'), function(){
  console.log('Express server listening on port ' + app.get('port'));
});

Routes
/ for new entries
/view for viewing all the users
/user/:id to see individual user information
/user/:id/edit to edit individual user information

With these tutorials you can start building fully functional web application. But to make it more secure, incorporate sessions, validation and error handling.

MongoDB Management Service To Rescue Your Application!

In today’s tutorial we’ll be looking at:
Installing Python
Installing PyMongo (Note: PyMongo is a python driver for MongoDB)
..and running mms-agent from your computer(localhost)

I’m using Windows 7 64-bit machine and the installation procedure are shown for the same.

mms-on-devices

Disclaimer: This is not a paid post and neither am I using any affiliate links in this post. I found MMS(MongoDB Management Service) incredibly useful and I wish I knew about it earlier. The monitoring and alerting services can save your applications reputation, and the backup service will literally save your application in disasters situations.

Requirements
MongoDB software: MongoDB – Getting Started Guide
Python 2.7.3
Setuptools
PyMongo driver software

mms-installation-software

Why use MMS ?

  • MMS tracks the key database and hardware metrics important for managing a MongoDB deployment
  • Performance Visualization
  • Custom Alerts
  • Back-up service ..etc

MongoDB Management Service To Rescue Your Application!


[youtube https://www.youtube.com/watch?v=HkvrksJL3Jg]

YouTube Link: https://www.youtube.com/watch?v=HkvrksJL3Jg [Watch the Video In Full Screen.]



Steps
Step 1: Install Python 2.7.3 at C:\Python27
Step 2: Install setuptools
Command to install setuptools

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C:\>cd Python27
C:\Python27>python D:\Python\setuptools\ez_setup.py

This installs easy_installer inside C:\Python27\Scripts folder. Easy installer helps in installing drivers.
Step 3: Now install Pythons MongoDB driver: PyMongo, with the following command.

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C:\Python27>cd Scripts
C:\Python27\Scripts>easy_install PyMongo

This would install PyMongo driver

Step 4: Start MongoDB server.

Step 5: Log into your MMS account, and download the MMS-AGENT. Extract the mms-agent files into a folder. In our case, we extract it to D:\Python\mms-agent
Step 6: Now run the mms-agent with the following command

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C:\>D:
D:\>cd Python
D:\Python>cd mms-agent
D:\Python\mms-agent>agent.py

This starts mms-agent.

Step 7: Go to your mms account – Fill the form with the host name, port number and other details

add-a-host-mongoDB-management-service-mms

Host Type: Standalone (for this example)
Internal Hostname: 127.0.0.1 (ip address for localhost)
Port: 27017 (default port used my MongoDB server)
DB Username and DB Password: are optional

inside-mms-account

Now it’ll start to fetch the meta data metrics via your IP address, as the agent is installed on your local machine and it knows your network IP address.

inside-mongoDB-management-service-account

Key things inside your account
Events: restart, shut-down or downtime etc
Alerts: To alert you in certain situations. You get emails for downtime etc, once setup.
Backup: It’s a premium service, which costs a little – backup service is pay-as-you-go service billed via credit card.
Users: You could invite people as admin or read only user. This way, you could bring in your team mates/colleagues to analyze and help you in performance tuning of your application.
Dashboard: You can customize your dashboard to give you quick view of key aspects of your application is a rich web console. You could have RAM usage statistics or query performance metrics etc.
Settings: Normal profile information: email id, password, phone verification etc.

Application Performance
Checking with the query performance and your application behavior from the very beginning of application development is recommended. And MMS is a perfect solution for this. This is one of the main reasons for this video tutorial. Running MMS on production servers is easy. You’ve bunch of plugins pre-installed at your host, you just need to enable it and insert the secret keys provided to you inside mms-agent file. But I would recommend you to watch for your application behavior from as early as in its development stage.

Note: You should know the norms of your application behavior, so that you can notice when there is abnormalities. MMS helps you effectively do that.

MongoDB Management Service is free service for getting metrics and setting alerts. And you only pay, if you use backup service and you pay for it as you use it.

Update / Edit Data In MongoDB: Node.js

Today lets look at editing and updating user entered data via Node.js application.

edit-update-data-mongoDB-nodejs

Related Read:
Connecting To MongoDB Using Mongoose: Node.js
Save data To MongoDB: Node.js
Fetch Data From MongoDB: Node.js
Fetch Individual User Data From MongoDB: Node.js
..please go through these 4 tutorials before proceeding further. It’ll take less than 20 min

link to individual profile page
view/index.jade

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ul
each user in users
 li
  a(href='/user/#{user._id}') #{user.name}

This displays list of all the users with their name, hyper-linked with their email id(present inside _id).

Adding Edit link
view/show.jade

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<h1>#{user.name}</h1>
ul
 li Age: #{user.age}
 li Email: #{user._id}
 
ul
 li 
  a(href="/user/#{user._id}/edit") Edit

This adds Edit link below each individual user information.

Edit Form
view/edit-form.jade

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<h1>Editing #{user.name}'s profile!</h1>
form(method="POST", action="/user/#{user._id}")
 input(type="hidden", name="_method", value="PUT")
 p Name:
  input(type="text", name="name", value="#{user.name}")
 p Age:
  input(type="number", name="age", value="#{user.age}")
 p
  input(type="submit")

It shows a message letting know the user, which user’s information they are editing. Also it fills the previous values for name and age. You can find a hidden field with the name _method, which helps to override POST method, and facilitates PUT method.

Edit and Update Routes
app.js

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app.get('/user/:id/edit', function(req, res){
res.render('edit-form', {user: req.userId});
});
 
app.put('/user/:id', function(req, res){
user.update({_id: req.params.id},
                   {
     name: req.body.name,
  age   : req.body.age
   }, function(err, docs){
 if(err) res.json(err);
else    res.redirect('/user/'+req.params.id);
 });
});
 
app.param('id', function(req, res, next, id){
user.findById(id, function(err, docs){
if(err) res.json(err);
else
{
req.userId = docs;
next();
}
});
});

Here id matches the param call, and using findById() method of mongoose, it fetches all the users present in the database. Once we call next(), it passes the control to next level. At /user/:id/edit route, we render edit-form.jade file and pass it with user information, to be filled inside the form input fields.

Once the user makes changes to the values and submits the form, all the values are passed to /user/:id route. In /user/:id route, we call update() method and specify which user information has to be updated in its first parameter, in second parameter we specify all the fields to be updated, and the third parameter is a callback method and it only takes error object as argument.

Using findByIdAndUpdate() method
app.js

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app.put('/user/:id', function(req, res){
user.findByIdAndUpdate({_id: req.params.id},
                   {
     name: req.body.name,
  age   : req.body.age
   }, function(err, docs){
 if(err) res.json(err);
else
{ 
   console.log(docs);
   res.redirect('/user/'+req.params.id);
 }
 });
});

Syntax of findByIdAndUpdate() method is same as that of update(), only difference is, findByIdAndUpdate() returns the result object as well as error object to the callback method. We can make use of result object to our advantage – in our above example, I’m simply illustrating the concept by logging the result object on to the console window.

Update / Edit Document In MongoDB: Node.js


[youtube https://www.youtube.com/watch?v=wdja8tYsvK8]

YouTube Link: https://www.youtube.com/watch?v=wdja8tYsvK8 [Watch the Video In Full Screen.]



Full Source Code: with findByIdAndUpdate() method
app.js

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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.get('/user/:id/edit', function(req, res){
res.render('edit-form', {user: req.userId});
});
 
app.put('/user/:id', function(req, res){
user.findByIdAndUpdate({_id: req.params.id},
                   {
     name: req.body.name,
  age   : req.body.age
   }, function(err, docs){
 if(err) res.json(err);
else
{ 
   console.log(docs);
   res.redirect('/user/'+req.params.id);
 }
 });
});
 
app.param('id', function(req, res, next, id){
user.findById(id, function(err, docs){
if(err) res.json(err);
else
{
req.userId = docs;
next();
}
});
});
 
 
app.get('/user/:id', function(req, res){
res.render('show', {user: req.userId});
});
 
app.get('/view', function(req, res){
user.find({}, function(err, docs){
if(err) res.json(err);
else    res.render('index', {users: docs})
});
});
 
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.redirect('/view');
});
});
 
var server = http.createServer(app).listen(app.get('port'), function(){
  console.log('Express server listening on port ' + app.get('port'));
});

/ for new entries
/view for viewing all the users
/user/:id to see individual user information
/user/:id/edit to edit individual user information

Note:
In real-world applications, it would make sense if only you are allowed to edit and update your data. To accomplish this – once the user logs in, store her _id value in a session variable. While the user issues an edit/update for a particular id, make sure the id she is requesting for edit/update matches with that present in the session variable!