Routes and controllers

MVC model

design pattern
used in ios development

routes - foward requests to appropriate controller functions controller functions - get data from models, create html, display data, and return to view views (templates) - used by controllers to render data

Routes

a section of express code that assocaites an HTTP verb, and url path, and a function to handle that pattern
route is a middleware created by var router = express.Router();

route path

define endpoints at which requests can be made
can be string patterns similar to regex

route parameters

named url segments used to capture values at specific positions in the url
e.g., /:user/
captures values are stored in req.params object
names must be made up of "word characters"

route functions

express middleware — must respond to or call another function in the chain
each functionis added to the middleware chain and is executed in order

middleware

objects that have access to req, res, and the next middleware function in the req-res cycle
e.g.,

app.use()
app.METHOD()
router.use()
express.static
express.json
express.urlencoded
app.use(cookieParser())

middleware can
- execute code
- change the req and response objects
- end the req-res cycle
- call next middleware function in stack

forms

in html — a collection of elements inside tags, containing a submit element
used to collect user input
flexible - can colect many different types of input
secure - can send data in post requests with cross site request forgery protection

e.g.,

<form action="/login" method="post">
	<label for="username">Username</label>
	<input id="username" type="text" name="username_field" value="">
	<input tupe="submit" value="OK">
</form>

sequence

display form
- blank or prepopulated fields
recieve data from user in HTTP post request
validate and sanitze data
if invalid - redisplay form with error messages, and user populated fields
if valid - perform required actions
redirect user to other page

validation and sanitization

required fields
correct format etc
remov/replace malicious input
can use express-validator module

const {body, validationResult} = require('express-validator');

[
//...
 body('name', "Empty name")
  .trim() //remove whitespace
  .isLength({min: 1}) //check length
  .escape(), //escape potentially dangerous chars
]

form routes

router.get() - serve page
router.post() - process request

2.8 KiB Raw Blame History