CS1520 recitation class slides

1. SIMPLE ROUTER
Salim Malakouti

2. Goal
 Work with dates in PHP
 Handle a simple form
 Get to know $_SERVER and $_GET variables
more
 Work with .htaccess files

3. What are we doing?
 We are creating a website that has two
functionalities:
 Calendar
 Shows the current date
 Birthday
 Receives birthday
 Prints it and tells you your age

4. What else
 Originally, the url of the pages are in the fomr:
 localhost/example1/calendar.php
 We want to change that to the style:
 localhost/example1/calendar
 Note that there are no .php extensions any more?

5. Where to start?
 Download
 Example 1
 From:
 http://salimm.me/courses/summer-2014/cs1520/
 Or
 http://salimm.me/courses/summer-
2014/cs1520/example1.zip

6. First lets take a tour
 Example 1 code shown in the class

7. Calendar.php
 Calendar.php ues the date function to current date. The
arguments of the function indicates the format to report the
date. For example:
 date('l the jS') will return “Monday the 10th”
 l stands for day in letters,
 the stands for “the” and use to escape these characters
 J stands for # of day in month and S stands for “th”
 date(“d”) returns day number
 date(“y”) returns 14 for 2014
 date(“Y”) returns year in complete form (2014)
 date(“d”) returns day of month with two leading zeros but date(“j”)
returns them without leading zeros
 date("F j, Y, g:i a"); returns May 19, 2014, 3:57 pm
 See the full doc here:
 http://php.net/manual/en/function.date.php

8. Birthday
 Change birthday.php in pages to accept the
inputs from user and print the following:
 Current Date (date only)
 Received birthday
 Calculate and print approximate age in years

9. Birthday
 Date
 Do not use the code in calendar.php. Retrieve year, month and
day individually using the date function and print the date
yourself. (HINT: you can use “Y”,”m”,”d”. The difference
between “Y” and “y” is that the later returns 14 for 2014.)
 In the second line Print the Birthday of user (Where can
you get that? Check the reserved variables $_GET,
$_SERVER, $_POST)
 In the third line print how old is the user in years
 You will need to cast the current and input year to integers to
be able to subtract them
 Sample output
 Today is 05/19/2014
 Your bithday is 5/3/2000
 You are 14 years old

10. Next we will create the
Router
 What do I we mean by a router?
 Routers work similar to a map. It receives the URL
user is requesting and allocates the
PHP|JSP|RUBY|etc file that is needed to process that
request
 Why?
 We will hide the structure of our code
 Simplicity: user doesn’t have to use odd long URL like
pages/birthday.php
 Security: We don’t want the hackers to know the structure of
our code
 Users don’t have to know the file extensions that we are
using
 Less confusing and more secure (we don’t want the hackers
to know the technology that we are using)
 Etc.

11. HTTP Protocol
 Before start with the code lets see what is
HTTP protocol:
 As we said last time: Is a protocol for
communication between server and client
 This communications are in form of requests and
responses
 (This is fairly an intuitive definition – refer to
teacher’s slides for the more adequate ones.)

12. Example
Request 1
Response 1
Request 2
Response 2
Request 3
Response 3

14. A sample request and
respone

15. Lets check the requests and
responses in our browser
 Open chrome
 Open Developer Tools
 View>Developer>Developer Tools
 Go to Network panel

16. A couple examples
 http://localhost/example1
 http://google.com
 http://localhost/example1/pages/birthday.php
 Submit the form

17. Request formats
 Request:
 GET
 Request to get a page
 HEAD
 Request to get only the response’s header
 POST
 Request to send data to the server (form)
 PUT
 Request to put a file or etc in server side (file or database)
 DELETE
 Delete a file from serverside
 Etc.

18. GET request in PHP
 How can we access the responses and
content of the requests?
 $_SERVER
 Include server info and request headers
 $_GET
 Includes al get data such as the data for the
birthday form

19. How to do it?
 Lets go back to our own example
 We want to create a router file which here will
be “index.php” that will receive all requests
and invoke the required php file for it?
 What do you think is the first step required here?

20. .htaccess
 We need to redirect everything to “index.php”
even if they are requesting something else.
 How?
 PHP can’t be used for that
 We use .htaccess file processed by Apache Server

21. Creating .htaccess file
 Create a .htaccess file in the root directory of
your project with the following content
# Turn rewriting on
RewriteEngine On
RewriteCond %{REQUEST_URI} !=/example1/index.php
RewriteRule .* /example1/index.php

22. What does this do?
# Turn rewriting on
RewriteEngine On
Turns on the RewriteEngine
RewriteCond %{REQUEST_URI} !=/example1/index.php
We will rewrite every request except ”example1/index.php” since we
want to avoid recursive redirections
RewriteRule .* /example1/index.php
We will change everything to “/example1/index.php”

23. Creating the router
 Check $_SERVER varaible usingthe following
command and see the content
 print_r($_SERVER);
 How can you use these information to find
which request is sent to “index.php” and which
file to invoke for it?

24. REDIRECT_URL
 Use $_SERVER['REDIRECT_URL'] and check
which page has been requested
 Use conditions
 How to invoke the proper php file for the
request?
 Use include

25. Index.php format
 Check for the following requests:
 /example1/birthday
 /example1/calendar
 /example1/index.php or /example1/
 Note that index.php by default is the router now. You
need to have the content of the old index.php in file
like main.php and invoke main.php when ever user is
actually requesting index.php
 Otherwise
 Print : Erro: Invalid Reuqest!!!

26. Test your application
 DONE