panpsychism

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WDI-Archer & WDI-Bowie

#Homework

Handling Sessions in Node

The video associated with this gist is located here.

Concept Questions

What are cookies (not the food kind)? Where can you find them in the browser?
What is a 'session'?
What kind of options can we set on the express-sessions pacakge when we .use it? what is required? What does the secret do?
How do we access the session storage in node?
What kind of things can be stored in a sessions?
What kind of things do you think sessions will eventually allow us to implement?

Exercises

Create a new express server and npm install and require everything you need (or use the one you made while following along the video if you had done so). Be sure to install express-sessions, body-parser, ejs, and mongoose. Also remember to touch a .gitignore file and ignore node_modules. Do the following with this server:

Create 2 pages: a welcome page and a form page. The form should ask the user for a name. When the user submits the form, save it in sessions and make the welcome page display: "Welcome, name". Refresh the welcome page, does the name persist?
Lets now use a database with stored information to populate our session.

Connect to mongo using mongoose
Create a mongoose schema for a user. Be sure to register it into a model. The schema should have a name (string) and color (also string)
Change the form route for setting the user's name. Instead of setting it in sessions, Create a new user in your user collection. Add an input for the person's favorite color and store that along with the user's name.
Create a new page for a login form. This form should take only a user's name. When a user submits, find there document in the database and set, in sessions, their name and color.
When a user goes to the welcome page, if they do not have a name set in sessions, redirect them to the login. If they have a name, render the welcome page with the normal welcome message and change the background to their color.

# Authentication with Express & Bcrypt & PG

adapted from https://github.com/ajbraus/wdi-homework/blob/master/express-auth-bcrypt.md

Objectives
Implement a password authentication strategy with bcrypt
Saved a logged-in user's data to the session
Implement routes for a user to `signup`, `/login`, and `/logout`
Apply session data in views

Authentication & Authorization

Authentication verifies that a user is who they say they are. When a user logs into our site, we authenticate them by checking that the password they typed in matches the password we have stored for them.
Authorization is the process of determining whether or not a user has permission to to perform certain actions on our site. For example, a user may be authorized to view their profile page and edit their own blog posts, but not to edit another user's blog posts.

Why do we hash (and salt) passwords?

In order to authenticate a user, we need to store their password in our database. This allows us to check that the user typed in the correct password when logging into our site.

The downside is that if anyone ever got access to our database, they would also have access to all of our users' login information. We use a hashing algorithm to avoid storing plain-text passwords in the database. We also use a salt to randomize the hashing algorithm, providing extra security against potential attacks.

Implementing Authentication

To give users the ability to sign up and log in to our site, we'll need:

Express: for building our application and handling requests
Middleware:
- body-parser: for handling incoming form data
- express-session: for setting sessions and cookies
- connect-pg-simple: connect sessions to pg
A users table in pg: for CRUD-ing users and setting up authentication methods
** A sessions table:** set up by connect-pg-simple
bcrypt: for hashing users' passwords

Challenges: Part 1

Goal: Setup project from starter code.

Pull from upstream, cd into the example application in classwork for today
Create the appropriate database name and connection string in pg.js
Create a users table that has an email and a password_digest (both strings)
Add a home route to server.js which renders home.html.ejs which has an anchor tag, signup that links to /users/new with text of Signup.
in the routes directory with a file users.js

var express = require('express');
var users = express.Router();
var bodyParser = require('body-parser');
var db = require('./../db/pg');

Add the corresponding code in your server.js

var userRoutes = require( path.join(__dirname, '/routes/users'));

[...]

app.use('/users', userRoutes)

define a route in this file. A get route /users/new

users.get('/new', (req,res) => {
  res.render('users/new.html.ejs')
})

the new route will render a file from views/users called new.html.ejs which will have a form with two input fields

The form will make a post request to /users

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
  <form action="/users" method="post">
    <label for="email">email</label>
    <input type="text" name="email">
    <label for="password">password</label>
    <input type="text" name="password">

    <input type="submit" value="Submit">
  </form>
</body>
</html>

Challenges: Part 2

So we now have the beginning of our signup flow but nothing his happening yet. Remember when we installed bcrypt earlier? We're going to now use that to save our users data to the db and "sign them up" for our application.

Goal: Set up bcrypt to hash our password and save that hashed password to the db

Install bcrypt and add it to pj.js

$ npm install bcrypt --save

at the top of pj.js add

var bcrypt = require('bcrypt');

What is salting?

Create a function called createUser that takes req, res, and next as arguments. Inside of that function create a function saveUser that takes two arguments, email and hash. Build the saveUser function as a standard pg function, It will insert an email and a password_digest into users.

function createUser(req, res, next) {
  createSecure(req.body.email, req.body.password, saveUser);

  function saveUser(email, hash) {
    // Get a Postgres client from the connection pool
    pg.connect(connectionString, function(err, client, done) {
      // Handle connection errors
      if(err) {
        done();
        console.log(err);
        return res.status(500).json({ success: false, data: err});
      }

      var query = client.query("INSERT INTO users (email, password_digest) VALUES ($1, $2);",
        [email, hash], function(err, result) {
          done()
          if(err) {
            return console.error('error, running query', err);
          }
          next()
      });
    });
  }
}

TOGETHER: build the createSecure function, explain how we call it as a callback.

add this line to the top

var salt = bcrypt.genSaltSync(10);

function createSecure(email, password, callback) {
  // hash password user enters at sign up
  bcrypt.genSalt(function (err, salt) {
    bcrypt.hash(password, salt, function (err, hash) {
      // this callback saves the user to our database with the hashed password
      callback(email, hash)
    });
  });
};

now call that function in the first line of create user, pass in the body, and a reference to saveUser as the callback

so let's go line by line and see what happens. We can now save users to our database and the password that is saved is encrypted.
make the corresponding post route in users.js that calls createUser and authenticates them it should redirect to the home page.

users.route('/')
  .post(db.createUser, (req, res) => {
    res.redirect('/');
  })

Challenges: Part 3 Log in

Create a log in anchor tag on our home page that links to users/login it should render users/login.html.ejs which has a form that makes a post request with email and password.

users.get('/login', (req,res) => {
  res.render('users/login.html.ejs')
})

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
  <form action="/users/login" method="post">
    <label for="email">email</label>
    <input type="text" name="email">
    <label for="password">password</label>
    <input type="text" name="password">

    <input type="submit" value="Submit">
  </form>
</body>
</html>

Cool so this post request goes no where let's build this part out together.

What are sessions?

npm install express-session --save npm install connect-pg-simple --save

psql sessions_test < node_modules/connect-pg-simple/table.sql

add the following to server.js

var session = require('express-session');
var pgSession = require('connect-pg-simple')(session);

app.use(session({
  store: new pgSession({
    pg : pg,
    conString : connectionString,
    tableName : 'session'
  }),
  secret: 'sooosecrett', // something we maybe want to save with dotenv *hint hint*
  resave: false,
  cookie: { maxAge: 30 * 24 * 60 * 60 * 1000 } // 30 days
}))

Add to pg.js

var session = require('express-session')

function loginUser(req, res, next) {
  var email = req.body.email;
  var password = req.body.password;

  // find user by email entered at log in
  pg.connect(connectionString, function(err, client, done) {
    // Handle connection errors
    if(err) {
      done();
      console.log(err);
      res.status(500).json({ success: false, data: err});
    }

    var query = client.query("SELECT * FROM users WHERE email LIKE ($1);",
      [email], function(err, result) {
        done()
        if(err) {
          return console.error('error, running query', err);
        }

        if (result.rows.length == 0) {
          res.status(204).json({success: false, data: 'no account matches that password'})
        } else if (bcrypt.compareSync(password, result.rows[0].password_digest)) {
          res.rows = result.rows[0]
          next()
        }
    });
  });
}

users.post('/login', db.loginUser, (req, res) => {
    req.session.user = res.rows

    // when you redirect you must force a save due to asynchronisity
    // https://github.com/expressjs/session/issues/167 **
    // "modern web browsers ignore the body of the response and so start loading
    // the destination page well before we finished sending the response to the client."

    req.session.save(function() {
      res.redirect('/')
    })
})

So it appears to be working, how can we check?

we can check the sessions table
we can also render a dynamic welcome message on the home page based on who is logged in!

add the object req.session.user object to the view!

app.get('/', function(req, res) {
  res.render('home.html.ejs', { user: req.session.user})
})

<% if (user) {%>
  <h3>Welcome <%= user.email %></h3>
<% } %>

Challenges: Part 4 logout

Goal: Add a route to log a user out

Add a delete route /logout to users.js
Install method override
Add a form/button on the home page that links to that delete route

What is that delete route going to delete? The user? what? Answer: the session!

<div>
  <form method="post" action="users/logout?_method=DELETE">
    <button>logout</button>
  </form>
</div>

users.delete('/logout', (req,res) => {
  req.session.destroy(function(err) {
    res.redirect('/')
  })
})

Challenges: Part 5 How do we restrict routes?

Goal:

create an image router an image view index.html.ejs that just

We need to check and see if there is a session, if there is, great! next() if not throw an error.

images.use(function(req, res, next) {
  console.log(req.session)
  if (req.session.user) {
    next()
  } else {
    res.status(301).json({succes: false, data: 'not logged in'})
  }
})```

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