Project: The Local Library Website (Part Seven)

Overview

already defined mongoose models to interact with the database
Used to script to create some initial library records.
Can now write this code to present that information to users
Determine what information we want to display in our pages
The define appropriate URLs for returning those resources.
Then we create routes (URL handlers) and views (templates) to display those pages
Already created the models
See the diagram below

Mostly setting up things to return dummy content in this one.

Routes Primer

Route is a section of express code that associates GET, POST etc with a URL path and a function to handle that pattern.
Several ways to create routes. We will use the express.Router middleware.
Keep our library related routes in a catalog module
Add routes for handling user accounts/ other functions, we can keep them grouped separately.

Defining and using separate route modules

Example below of how to create a route module and then use it

// wiki.js - Wiki route module.
var express = require('express');
var router = express.Router();

// Home page route.
router.get('/', function (req, res) {
  res.send('Wiki home page');
})

// About page route.
router.get('/about', function (req, res) {
  res.send('About this wiki');
})

module.exports = router;

First, we require express,
To use it in our main app file, we need to require the route module.
Then we call Use on it, explaining which path we want to use.
The two routes get / and get /about are accessible.

var wiki = require('./wiki.js');

// ...

app.use('/wiki', wiki);

Route Functions

Typical route functions
About route, for example, uses the GET method – only responds to HTTP Get requests.
First argument to this method is the URL path, second is the callback that will be invoked if an HTTP GET request with the path is received.

router.get(‘/about’, 
function (req, res) {
res.send(‘About this wiki’);
})

The callback begins at function. Also anonymous.

Route parameters

Named URL segments used to capture values at specific positions in the URL.
Use a colon, and then the name.
Captured values are stored in the req.params object.
For example req.params.your_parameter_name
For example:

http://localhost:3000/users/34/books/8989

We can extract this information as below:

app.get('/users/:userId/books/:bookId', function (req, res) {
  // Access userId via: req.params.userId
  // Access bookId via: req.params.bookId
  res.send(req.params);

})

Routes needed for the Local Library

URLs used for our pages are listed below.
Object – replaced by the name of each of our models.
- catalog/ — The home/index page.
- catalog/<objects>/ — The list of all books, bookinstances, genres, or authors (e.g. /catalog/books/, /catalog/genres/, etc.)
- catalog/<object>/<id> — The detail page for a specific book, bookinstance, genre, or author with the given _id field value (e.g. /catalog/book/584493c1f4887f06c0e67d37).
- catalog/<object>/create — The form to create a new book, bookinstance, genre, or author (e.g. /catalog/book/create).
- catalog/<object>/<id>/update — The form to update a specific book, bookinstance, genre, or author with the given _id field value (e.g. /catalog/book/584493c1f4887f06c0e67d37/update).
- catalog/<object>/<id>/delete — The form to delete a specific book, bookinstance, genre, author with the given _id field value (e.g. /catalog/book/584493c1f4887f06c0e67d37/delete).
First home page and list pages don’t encode any additional information
Results returned will depend on the model type and the content in the database.

Create the route-handler callback functions

Create the skeletons of the callback functions
Callbacks – stored in separate modules for books, book instances, Games and authors.

/express-locallibrary-tutorial //the project root

/controllers

authorController.js

bookController.js

bookinstanceController.js

genreController.js

Author Controller

var Author = require('../models/author');
// Display list of all Authors.
exports.author_list = function(req, res) {
    res.send('NOT IMPLEMENTED: Author list');
};

// Display detail page for a specific Author.
exports.author_detail = function(req, res) {
    res.send('NOT IMPLEMENTED: Author detail: ' + req.params.id);
};

// Display Author create form on GET.

exports.author_create_get = function(req, res) {
    res.send('NOT IMPLEMENTED: Author create GET');
};

// Handle Author create on POST.
exports.author_create_post = function(req, res) {
    res.send('NOT IMPLEMENTED: Author create POST');
};

// Display Author delete form on GET.
exports.author_delete_get = function(req, res) {
    res.send('NOT IMPLEMENTED: Author delete GET');
};

// Handle Author delete on POST.
exports.author_delete_post = function(req, res) {
    res.send('NOT IMPLEMENTED: Author delete POST');
};

// Display Author update form on GET.
exports.author_update_get = function(req, res) {
    res.send('NOT IMPLEMENTED: Author update GET');
};

// Handle Author update on POST.
exports.author_update_post = function(req, res) {
    res.send('NOT IMPLEMENTED: Author update POST');
};

Others are very similar to above.

Update the index route module

in /routes/index.js:

// GET home page.

router.get('/', function(req, res) {

  res.redirect('/catalog');

});

Update app.js

var indexRouter = require('./routes/index');

var usersRouter = require('./routes/users');

var catalogRouter = require('./routes/catalog');  //Import routes for "catalog" area of site

app.use('/', indexRouter);

app.use('/users', usersRouter);

app.use('/catalog', catalogRouter);  // Add catalog routes to middleware chain.

Testing the Routes

DEBUG=express-locallibrary-tutorial:* npm start