Layouts and Controllers

Express gives us a lot of flexibility out of the box (configuration over convention). While this is a good thing, it can become a problem when we don't take the time to organize our project.

Objectives

  • Utilize layouts and controllers in an Express app

Prereqs:

  • ability to create a basic node/express app with basic routes and views

Set Up a new Express App

Before we do anything else, let's set up a new basic Express app called faves-hates-app.

1. Create a new project

2. Initialize Node

3. Install Dependencies

  • express

  • ejs

4. Set up Express

  • index.js file

  • require express

  • create an instance of express

  • tell the app which port to listen to

5. Set up EJS

  • set view engine to ejs

  • create a views folder

EJS Layouts

Adding partials can dry up the code a bit, but EJS Layouts can take this modularity even farther and make a big diffence with large applications.

EJS layouts is a node package that allows us to create a boilerplate (aka a layout) that we can inject content into based on which route is reached. Layouts normally include header and footer content that you want to display on every page (navbar, sitemap, logo, etc.).

Install EJS Layouts

Step 1: Install EJS layouts

Install express-ejs-layouts via npm

npm install express-ejs-layouts

Step 2: Set up EJS layouts

Require the module and add it to the app.

index.js

var express = require('express');
var app = express();
var ejsLayouts = require('express-ejs-layouts');

app.set('view engine', 'ejs');
app.use(ejsLayouts);

app.listen(3000)

What is app.use()? This is an express function that indicates middleware. Middleware functions intercepts the request object when it comes in from the client, but before it hits any route. We'll see more examples of middleware later.

How are you supposed to know that ejs layouts requires middleware? The docs.

Step 3: Create a Layout

In the root of the views folder, add a layout called layout.ejs. It must be called layout.ejs, as mandated by express-ejs-layouts.

layout.ejs

<!DOCTYPE html>
<html>
<head>
  <title>Faves&Hates</title>
</head>
<body>
  <%- body %>
</body>
</html>

This layout will be used by all pages, and the content will be filled in where the <%- body %> tag is placed. <%- body %> is a special tag used by express-ejs-layouts that cannot be renamed.

Step 4: Use the Layout

In the views folder, create a home.ejs file:

home.ejs

<h1>This is the home page!</h1>

Now create a home route in index.js below the middleware:

app.get('/', function(req, res) {
  res.render('home');
});

Ejs will assume that home means home.ejs. Now starte nodemon and check that your home page renders as desired.

Step 5: Set up a few more views/routes

index.js

app.get('/animals', function(req, res) {
  res.render('animals', {title: 'Favorite Animals', animals: ['sand crab', 'corny joke dog']})
});

animals.ejs

<h1><%= title %></h1>
<ul>
  <% animals.forEach(function(animal) { %>
    <li><%= animal %></li>
  <% }) %>
</ul>

Visit localhost:3000/animals to make sure that all is well.

Now create a foods view/route that displays your favorite foods, just like you did with animals.

Bonus: Add Navigation

Add a simple navigation list to the to of the layout page so there's a link to every page from every page:

layout.ejs

<!DOCTYPE html>
<html>
<head>
  <title>Faves&Hates</title>
</head>
<body>
  <ul>
    <li><a href='/foods'>Favorite Foods</a></li>
    <li><a href='/animals'>Favorite Animals</a></li>
  </ul>
  <%- body %>
</body>
</html>

Controllers & Express Router

Controllers become important organizational tools when you start making apps with several views, so let's create a few more views.

1. Inside the views folder, create a faves folder and move your foods.ejs and animals.ejs files into it.

2. Inside the views folder, create a hates folder that also contains a foods.ejs file and an animals.ejs file, but design these views to display your least favorite foods and animals.

We have been placing all routes into index.js when creating a Node/Express app, but this can get cumbersome when dealing with many routes. The solution is to group related routes and separate these groups into separate files. These files will go into a controllers folder.

3. Create a controllers folder inside the root directory that will contain all routes except for the home route.

4. Inside the controllers folder, create a file called faves.js with the following routes:

app.get('/foods', function(req, res) {
  res.render('faves/foods', {title: 'Favorite Foods', foods: ['coconut', 'avocado']});
});

app.get('/animals', function(req, res) {
  res.render('faves/animals', {title: 'Favorite Animals', animals: ['sand crab', 'corny joke dog']})
});

But wait! app doesn't exist in this file! Express has a Router() function that will help us wrap these routes into a module that we'll export back into our main server file.

5. Add these wrapper lines of code to faves.js, and replace app with router.

var express = require('express');
var router = express.Router();

router.get('/foods', function(req, res) {
  res.render('faves/foods', {title: 'Favorite Foods', foods: ['coconut', 'avocado']});
});

router.get('/animals', function(req, res) {
  res.render('faves/animals', {title: 'Favorite Animals', animals: ['sand crab', 'corny joke dog']})
});

module.exports = router;

6. Now back in index.js, we just need to add some middleware to get these routes working again!

index.js

app.use('/faves', require('./controllers/faves'));

Note that we defined the routes relative to the definition in app.use. In other words, take note that our URL patterns in faves.js don't inclued '/faves', because that is taken care of by the middleware.

Check that these routes are working by visiting http://localhost/faves/foods and http://localhost/faves/animals.

Now finish the lab off by doing the same for your hates pages!

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