TP Express CRUD

Home page

The first modification to app.js is to get rid of the template and just hard-wire some HTML for the home page. Make it look like this

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

/* GET home page. */
router.get('/', function (req, res, next) {
    var html = '<p>got home page</p>';
    res.send(html);
});

module.exports = router;

Pretty trivial: localhost:3000 just displays a header saying what's up.

NB: All further additions to app.js in what follows go before the module.exports = router; line. This is important.

All items

The idea now is to get all items from the database. Adding

/* Read stuff. */

/* GET everything */
router.get('/read', function (req, res, next) {
    // get all entities from db
    var html = '<p>read everything from db</p>';
    res.send(html);
});

and browsing to localhost:3000/read in the address bar should do it. The line // get all entities from db is where the code to actually access the database would go.

Specific item

Now we'd like to get just one specific item from the database. Adding

/* GET something specific. */
router.get('/read/:id', function (req, res, next) {
    // get indicated entity from db
    var html = '<p>read ' + req.params.id + ' from db</p>';
    res.send(html);
});

and browsing to localhost:3000/read/foo should do it.

Well, that was pretty dull.

Specific item via URL

Huh? How come this isn't titled Delete with DELETE? Well, the browser address bar can only cope with GET, so we have to improvise and DELETE with GET. Fortunately that's not too hard. Add the following

/* Delete stuff.
 A browser address bar can only issue GET requests.
 A form can only issue GET and POST requests.
 But we can improvise. */

/* DELETE something specific from the URL. */
router.get('/delete/:id', function (req, res, next) {
    if (req.path == '/delete') {
       next();
    }
    // remove indicated entity from db
    var html = '<p>deleted ' + req.params.id + ' from db</p>';
    res.send(html);
});

Now localhost:3000/delete/foo in the browser address bar will remove the item foo from the database.

Specific item via form

We can also send a form where the information on what to delete is to be filled in. Note that the form is POSTed back to the server; forms don't do PUT.

/* DELETE something specific by posting a form.
 GET form to fill in with details of object to delete.
 POST it back to the server */
router.get('/delete', function (req, res, next) {
    var html = '<form method="post" action="/deleted">' +
               '<div><input type="text" name="something" placeholder="delete something"></div>' +
               '<div><input type="submit" value="go"></div>' +
               '</form>';
    res.send(html);
});

router.post('/deleted', function (req, res, next) {
    // parse form and remove indicated entity from db
    var html = '<p>deleted ' + req.body.something + ' from db</p>';
    res.send(html);
});

Then just localhost:3000/delete will bring up the form.

Specific item via form

Same deal as with DELETE - the address bar can only send GET, and a form can only GET and POST

/* Update stuff.
 A browser address bar can only issue GET requests.
 A form can only issue GET and POST requests.
 But we can improvise. */

/* UPDATE something specific from the URL. */
router.get('/update/:id', function (req, res, next) {
    var html = '<form method="post" action="/updated">' +
               '<div>' + req.params.id +
                   ': <input type="text" name="something" placeholder="something"></div>' +
               '<input type="hidden" name="id" value="' + req.params.id + '">' +
               '<div><input type="submit" value="go"></div>' +
               '</form>';
    res.send(html);
});

/* POST to parse form and update something specific. */
router.post('/updated', function (req, res, next) {
    // parse form and insert updated entity into db
    var html = '<p>edited and updated ' + req.body.id + ': 
                   ' + req.body.something + ' in db</p>';
    res.send(html);
});