class 6 - php web programming

PHP Web Programming

Outline

Request Types

1- ‘GET’ request:

Is the most common type of request. An example of it is writing the URL in your browser then clicking enter.

Get requests can have parameters passed with the URL.

http://www.google.com/search?q=ronaldo&client=ubuntuParametersDomain nameProtocol Script

Request Types

1- ‘POST’ request:

It is another type of request in which the browser passes the parameters to the server in a hidden way. Example of this is submitting a form with a method=post.

<form action=“/search” method=“POST”>

Text : <input type=“text” name=“query” /><input type=“submit” value=“Search” />

</form>

Getting Parameter Values in PHP

In PHP we have some special variables that store the parameters that are passed during the request.

1- $_GET

This is an associative array that holds the parameters that are passed in a GET request.For example:If I have a php script named “getit.php” on my local machine that looks like this :

<?phpvar_dump($_GET);

?>


When opening it like this :

http://localhost/getit.php?name=john&age=15

The out put should be like this :

array(2) { ["name"]=> string(4) "john" ["age"]=> string(2) "15"}


2- $_POST :

This is an associative array that contains all the passed parameters using POST request.

For example:

If we have page called “form.php” that contains the following :

<form action=“/postit.php” method=“POST”>Text : <input type=“text” name=“query” /><input type=“submit” value=“Search” />

</form>


And the script “postit.php” has :<?php

var_dump($_POST);?>

Opening that script :http://localhost/form.php

After opening that and putting a value “Hello” in the text box and clicking on the search button, you should see :

array(1) { ["query"]=> string(5) "Hello"}


3- $_REQUEST:

This variable will contain all the values from the associative arrays $_GET and $_POST combined ( It also contains the values of the variable $_COOKIE which will talk about later).

It is used in case I allow the user to pass parameters with the method he likes ( GET or POST ).

Exercise

Write a PHP script that allows the user to enter his/her name in a field and after submitting, It should greet them.

For example:

if the user entered “Mohamed” the script should show “Hello Mohamed”.

Exercise Solution

1. Script name “form.php”:

<html><body>

<form action=“/greet.php” method=“POST”>

Text : <input type=“text” name=“name” />

<input type=“submit” value=“Submit” />

</form></body>

</html>

Exercise Solution

1. Script name “greet.php”:

<?php

echo “Hello “ . $_POST[‘name’];

?>

Handling file uploadsUploading a file to a PHP script is easy, you just need to set the enctype value to “multipart/form-data” and the form method=POST.

The multi-dimension array called “$_FILES” will contain any information related to the uploaded files.To demonstrate, here is an example :We have a script named “form.php” that contains :

<form enctype="multipart/form-data“ action=“upload.php" method="POST">File: <input name="uploadedfile" type="file" /><input type="submit" value="Upload" />

</form>

Handling file uploadsAnd we have another script named “upload.php” :

<?php

if( is_uploaded_file($_FILES['uploadedfile']['tmp_name']) ){echo file_get_contents($_FILES['uploadedfile']['tmp_name']);

}

?>

This script will show the contents of the file once uploaded.

ExerciseWork on the previous exercise to allow the user to enter an email address and check whether the email is valid or not and show a message to the user telling so.

Exercise SolutionThe first script is named “form.php” :

<html><body>

<form action=“/doit.php” method=“POST”>

Name: <input type=“text” name=“name” />E-mail: <input type=“text” name=“email” />

<input type=“submit” value=“Submit” />

</form></body>

</html>

Exercise SolutionThe first script is named “doit.php” :

<?php

echo "Your name : ". $_POST['name'] . "<br/>";echo "Your email: ";

if( preg_match( '/^[\w]+@[\w]+\.[a-z]{2,3}$/i', $_POST['email']) == 1 )

echo $_POST['email'];else

echo "Not Valid“;

?>

CookiesCookies are a mechanism for storing data in the remote browser and thus tracking or identifying return users.

• Example of a cookie response header :Set-Cookie: name2=value2; Domain=.foo.com; Path=/;Expires=Wed, 09 Jun 2021 10:18:14 GMT

• Example of a cookie request header :Cookie: name=value; name2=value2

Flash Back – Class 1

Cookies in PHPPHP provides the function setcookie() and the global variable $_COOKIE to allow us to deal with cookies.

bool setcookie ( string $name [, string $value [, int $expire = 0 [, string $path [, string $domain [, bool $secure = false [, bool $httponly = false ]]]]]] )

setcookie() defines a cookie to be sent along with the rest of the HTTP headers. Like other headers, cookies must be sent before any output from your script.

Cookies in PHPThe $_COOKIE super global is used to get the cookies set.

Example:

<?phpsetcookie(‘name’, ‘mohamed’, time() + 3600 );

?>

In another script on the same domain we can do this :

<?phpecho $_COOKIE[‘name’]; // mohamed

?>

Sessions• Session support in PHP consists of a way to preserve

certain data across subsequent accesses. • This is implemented by creating a cookie with a random

number for the user and associate this data with that id.• PHP maintains a list of the user ids on the server with

corresponding user data.

Example:

<?phpsession_start();$_SESSION[‘age’] = 20;

?>

SessionsAnother script on the same domain contains:

<?php

session_start();

echo $_SESSION[‘age’] ; // 20

?>

SessionsThings to note here :

•The session_start() function should be called the first thing in the script before any output in order to deal with sessions.•Use session_destroy() if you want to destroy the session data.

ExerciseWrite a web page that uses sessions to keep track of how many times a user has viewed the page. The first time a particular user looks at the page, it should print something like "Number of views: 1." The second time the user looks at the page, it should print "Number of views: 2," and so on.

Exercise Solution<?php

session_start();

if( !isset($_SESSION['views']) )$_SESSION['views'] = 0;

++$_SESSION['views'];

echo "Number of views : " . $_SESSION['views'];?>

AssignmentWrite a web page that uses sessions to keep track of how long the user viewed the page. It should output something like “You have been here for X seconds“. Tip use date function http://php.net/manual/en/function.date.php

http://php.net/manual/en/function.date.php

What's Next?• Object Oriented Programming.

Questions?

class 6 - php web programming

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