Mohammad Al-Samarah

Chapter - 4

Web Programming

Outline• Overview about Web Page

• HTML Form Creation

• FORM

• Input

• INPUT control types

• GET & POST

• PHP File Upload

• PHP Include Files

• Headers

• Cookie

• Sessions

Overview about Web Page• Most people think of a web page as nothing more than a

collection of HTML code . This is fine if you happen to be a web

designer .

• But as a PHP developer we talk about web server that generation

of a document starts with an HTTP request ,in which the client

requests access to a resource using on method from short list

methods.

• The client can also send data payload (called request),once

request is received , the sever decoded the data that it has

received and passes it on to the PHP interpreter.

Overview about Web Page

• A web application receives input from the

user via form input

• Handling form input is the cornerstone of a

successful web application – everything

else builds on it

Overview about Web Page

• The browser interprets the HTML source for a

particular page

– Result is a combination of text, images, and

entry fields

– Each entry field has a specific name

• User fills in these fields, (with potentially some

client-side input checking via JavaScript) and then

selects a submission button

Overview about Web Page

• The browser reads the input fields, and

creates a message that is sent to the

server

– A series of name, value pairs

HTML Form Creation• FORM

– Encloses all input fields

– Defines where and how to submit the form data

• INPUT

– Defines a specific input field

• TEXTAREA

– Creates a free-form text fill-in box

• SELECT

– Creates a menu

– OPTION defines options within the menu

FORM• FORM attributes

– action

• URL of the resource that receives the filled-in form

• This is the URL of your PHP code that receives the input

– method

• Choices are “get” or “post” – you should choose “post”

– enctype

• MIME type used to send results. By default is application/xww-

form-urlencoded

• Would use multipart/form-data if submitting a file

(INPUT,type=file)<FORM action=“MyHandler.php” method=“post”>

INPUT• INPUT attributes

– type: the kind of user input control

– name: the name of the control

• This gets passed through to the handling code

• In PHP: $_POST[‘name’]

– value: initial value of the control

– size: initial width of the control

• in pixels, except for text and password controls

INPUT

– maxlength: for text/password, maximum number of

characters allowed

– checked: for radio/checkbox, specifies that button is on

– src: for image types, specifies location of image used to

decorate input button

INPUT Control Types

• text: single input line

• password: single input line, with input

characters obfuscated

• checkbox: creates a check list

• radio: creates a radio button list (checkbox,

where inputs are mutually exclusive – only one

input at a time)

• button: push button

• hidden: a hidden control. No input field is

visible, but value is submitted as part of the form

INPUT Control Types

• Special buttons

– submit: the submit button. Causes input to be sent to the server

for processing

– reset: the reset button. Causes all input fields to be reset to their

initial values

• File upload

– file: creates a file upload control

Example<FORM action=“mypage.php" method="post">

First name: <INPUT type="text“ name="firstname"><BR>

Last name: <INPUT type="text“ name="lastname"><BR>

email: <INPUT type="text“ name="email"><BR>

<INPUT type="radio" name="sex“ value="Male"> Male<BR>

<INPUT type="radio" name="sex“ value="Female">

Female<BR>

<INPUT type="submit" value="Send">

<INPUT type="reset">

</FORM>

Example

Receiving form input in PHP

• Upon receiving a form submission, PHP

automatically creates and populates two arrays

with the form input data

– Either : _POST[] or _GET[], depending on the

FORM method type (post or get)

– Additionally, _REQUEST[] is also created

• The array indicies are the names of the form

variables (INPUT name=…)

• The array value is the user entry data

Receiving form input in PHP

• The two method allows you to send data

as part of the query string ,   The

predefined variable is used to collect

values in a form ( $_GET , $_POST ).

GET

• Information sent from a form with the GET method is visible

to everyone (it will be displayed in the browser's address

bar) and has limits on the amount of information to send.

http://localhost/send.php?Var1=value1&Var2=value2&Var3=value3

GET - Example <html><body>

<form action="welcome.php" method="get">

Name: <input type="text" name="fname" />

Age: <input type="text" name="age" />

<input type="submit" />

</form>

</body></html>

<?php

echo “Welcome”. $_GET["fname"] .” <br />”;

echo “You are “.$_GET["age"].” years old!”;

?>.

welcome.php

GET - Example

<html> <body>

<h4> Order Form</h4>

<form action="process.php" method=“get"> <select

name="item"> <option>Paint</option>

<option>Brushes</option> <option>Erasers</option>

</select> Quantity: <input name="quantity"

type="text" /> <input type="submit" />

</form>

</body></html>

GET - Example

<html><body>

<?php

$quantity = $_GET['quantity'];

$item = $_GET['item'];

echo "You ordered ". $quantity . " " . $item . ".<br />";

echo "Thank you for ordering from Tizag Art Supplies!";

?>

</body></html>

process.php

GET - Example

POST

• Information sent from a form with the POST method is

invisible to others and has no limits on the amount of

information to send.http://www.example.com/send.php

POST - Example

<form action="welcome.php" method="post">

Name: <input type="text" name="fname" />

Age: <input type="text" name="age" />

<input type="submit" />

</form>

<?php

echo “Welcome”. $_POST["fname"] .” <br />”;

echo “You are “.$_POST["age"].” years old!”;

?>.

welcome.php

POST - Example

REQUEST

• The predefined $_REQUEST variable contains the contents

of both $_GET, $_POST, and $_COOKIE.

• The $_REQUEST variable can be used to collect form data

sent with both the GET and POST methods.

http://www.example.com/send.php

http://localhost/send.php?Var1=value1&Var2=value2&Var3=value3

 REQUEST - Example

<?php

echo “Welcome”.  $_REQUEST["fname"] .” <br

/>”;

echo “You are “.  $_REQUEST["age"].” years

old!”;

?>.

welcome.php

Array Notation

• We can create arrays by using array notation..

<?php

forech($_GET[‘arra’] as $x)

{

echo $x

}

?>

http://localhost/send.php?user=data&arra[]=data1&arra1[]=data2

Array Notation

• We can create arrays by using array notation..

<?php

echo $_GET[‘arra’][‘x’];

echo $_GET[‘arra’][‘s’];

?>

http://www.example.com/send.php?user=data&arra[‘x’]=data1&arra[‘s’]=datax

PHP File Upload

• To allow users to upload a file to the server, you first need

to provide a form for them to specify which file they want to

upload. Once they click the submit button of the form, the

action page is called. This is the page that needs to contain

the PHP code to process the uploaded file.

PHP File Upload• Before a user can upload a file, you need to provide them with an

interface that allows them to select a file and initiate the upload.

• The following code is an example of an input form. There are a

couple of important things to note about this code:

• The action attribute points to a .php file. This is the file that will

process the uploaded file.

• There is an attribute called enctype, and its value is

multipart/form-data.

• One of the input fields has type="file".

PHP File Upload

<html> <head> <title>PHP File Upload Example</title>

</head><body>

<form enctype="multipart/form-data" method="post"

action="uploadFile.php">

<input type="file" name="fileToUpload" /><br />

<input type="submit" value="Upload File" />

</form>

</body> </html>

The Action Page

• Once the user uploads a file, the file is uploaded into a

temporary directory on the server. If you don't move the file it

will disappear. Therefore, your action page needs to move the

file to another location where it can stay as long as you want it

to.

• Whenever a file is uploaded, you can find out certain

information about the file including its name, type, size, as well

as the name of the temporary file on the server. These details

are made available to you via a PHP array called $_FILES.

Displaying Details of the Uploaded File

• This code simply displays the details of the uploaded file. It

doesn't move the file to another location - we'll get to that next.

For now, you can use this code in conjunction with the above

input form to demonstrate what happens when you upload a

file to the server.

• Notice the PHP $_FILES array which contains info about the file.

Note that we also divide the file size by 1024 in order to

convert it into kb.

-(Ignore any carriage returns in this example - each table

row should be on one line).

Displaying Details of the Uploaded File

<?php

echo "<table border=\"1\">";

echo "<tr><td>Client Filename: </td>

<td>" . $_FILES["fileToUpload"]["name"] . "</td></tr>";

echo "<tr><td>File Type: </td>

<td>" . $_FILES["fileToUpload"]["type"] . "</td></tr>";

echo "<tr><td>File Size: </td>

<td>" . ($_FILES["fileToUpload"]["size"] / 1024) . " Kb</td></tr>";

echo "<tr><td>Name of Temp File: </td>

<td>" . $_FILES["fileToUpload"]["tmp_name"] . "</td></tr>";

echo "</table>";

?>

Displaying Details of the Uploaded File

• The above code results in something like this:

Client Filename: Water lilies.jpg

File Type: image/jpeg

File Size: 81.830078125 Kb

Name of Temp File: C:\WINDOWS\TEMP\php48B2.tmp

Moving the Temp File

• As mentioned, if we want to keep the file on the server,

we need to move it to another location (of our choice).

The following code demonstrates how to move the file

from the temporary location.

move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], "C:/upload/" . $_FILES["fileToUpload"]["name"]);

Checking for Errors

• The $_FILES array includes an item for any errors that

may result from the upload. This contains an error code.

If there are no errors, the value is zero ( 0 ).

• You check this value within an "If" statement. If the value

is greater than zero, you know an error has occurred and

you can present a user friendly message to the user.

Otherwise you can processing the file.

Checking for Errors<?php

if ($_FILES["fileToUpload"]["error"] > 0)

{

echo "Apologies, an error has occurred.";

echo "Error Code: " . $_FILES["fileToUpload"]["error"];

}

else

{

move_uploaded_file($_FILES["fileToUpload"]["tmp_name"],

"C:/upload/" . $_FILES["fileToUpload"]["name"]);

}

?>

Restricting File Type/Size

• Letting your users upload files to your server can be very risky.

If you're not careful, you could get users uploading all sorts of

files - perhaps including harmful executables etc. You could also

find one day that you've run out of disk space because some

users have been uploading enormous files.

• You can restrict the file types and file sizes by using an "if"

statement. If the file type and size are acceptable, processing

can continue, otherwise, display a message to the user.

Restricting File Type/Size

• Important Note: This doesn't prevent the temp file from being

created. The file needs uploaded to the server before PHP can

find out the file size and type. This simply prevents the file from

being moved to your "permanent" location - hence the file

should disappear and (hopefully) not become a problem. In any

case, I recommend that you install good anti-virus software

before allowing users to upload files to your server.

Restricting File Type/Size<?php

if (($_FILES["fileToUpload"]["type"] == "image/gif")

|| ($_FILES["fileToUpload"]["type"] == "image/jpeg")

|| ($_FILES["fileToUpload"]["type"] == "image/png" )

&& ($_FILES["fileToUpload"]["size"] < 10000))

{

move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], "C:/upload/" .

$_FILES["fileToUpload"]["name"]);

}

else

{

echo "Files must be either JPEG, GIF, or PNG and less than 10,000 kb";

}

?>

PHP Include Files

• In PHP, you can insert the content of one PHP file into

another PHP file before the server executes it.

• The include and require statements are used to insert

useful codes written in other files, in the flow of execution.

• Include and require are identical, except upon failure:

require will produce a fatal error (E_COMPILE_ERROR)

and stop the script

include will only produce a warning (E_WARNING) and

the script will continue

PHP Include Files

• Including files saves a lot of work. This means that you can

create a standard header, footer, or menu file for all your

web pages. Then, when the header needs to be updated,

you can only update the header include file.include 'filename';

or

require 'filename';

PHP Include Files

<html>

<body>

<?php include 'header.php'; ?>

<h1>Welcome to my home page!</h1>

<p>Some text.</p>

</body>

</html>

PHP Include Files

• Assume we have a standard menu file that should be used

on all pages. "menu.php":

<?phpecho '<a href="/default.php">Home</a><a href="/tutorials.php">Tutorials</a><a href="/references.php">References</a><a href="/examples.php">Examples</a> <a href="/about.php">About Us</a> <a href="/contact.php">Contact Us</a>';?>

PHP Include Files

• All pages in the Web site should include this menu file. Here is how

it can be done:<html><body>

<div class="leftmenu"><?php include 'menu.php'; ?></div>

<h1>Welcome to my home page.</h1><p>Some text.</p>

</body></html>

Header

• The header() function sends a raw HTTP

header to a client.

• It is important to notice that header() must

be called before any actual output is sent

(In PHP 4 and later, you can use output

buffering to solve this problem):

Header

• The header() function sends a raw HTTP

header to a client.

• It is important to notice that header() must

be called before any actual output is sent

(In PHP 4 and later, you can use output

buffering to solve this problem):

Header

header(string,replace,http_response_code)

Parameter Description

string Required. Specifies the header string to send

replace Optional. Indicates whether the header should replace previous or add a second header. Default is TRUE (will replace). FALSE (allows multiple headers of the same type)

http_response_code

Optional. Forces the HTTP response code to the specified value (available in PHP 4.3 and higher)

Header

<html>

<?php

// This results in an error.

// The output above is before the header() call

header('Location: http://www.example.com/');

//this is redirect to this website.

?>

Cookie

• A cookie is often used to identify a user. A

cookie is a small file that the server

embeds on the user's computer. Each time

the same computer requests a page with a

browser, it will send the cookie too. With

PHP, you can both create and retrieve

cookie values.

How to Create a Cookie?

How to Create a Cookie?

• The setcookie() function is used to set a cookie.

• Note: The setcookie() function must appear

BEFORE the <html> tag.

setcookie(name, value, expire, path, domain);

How to Create a Cookie?

• We will create a cookie named "user" and assign

the value "Ali" to it. We also specify that the

cookie should expire after one hour:

<?php

setcookie("user", "Ali", time()+3600);

?>

Cookie

• Note: The value of the cookie is

automatically URLencoded when sending

the cookie, and automatically decoded

when received (to prevent URLencoding,

use setrawcookie() instead).

How to Create a Cookie?

• You can also set the expiration time of the cookie

in another way. It may be easier than using

seconds.<?php

$expire=time()+60*60*24*30;

setcookie("user", "Alex Porter", $expire);

?>

How to Retrieve a Cookie Value?

• The PHP $_COOKIE variable is used to retrieve a cookie

value. 

In the example below, we retrieve the value of the cookie

named "user" and display it on a page:<?php

echo $_COOKIE["user"]; // Print a cookie

print_r($_COOKIE); // A way to view all cookies

?>

How to Delete a Cookie?

• When deleting a cookie you should assure that the

expiration date is in the past.

<?php

// set the expiration date to one hour ago

setcookie("user", "", time()-3600);

?>

Session

• PHP session variable is used to store information

about, or change settings for a user session.

Session variables hold information about one

single user, and are available to all pages in one

application.

• Before you can store user information in your PHP

session, you must first start up the session.

Starting a PHP Session

• <?php session_start(); ?>

• The code above will register the user's session

with the server, allow you to start saving user

information.

• The correct way to store and retrieve session

variables is to use the PHP $_SESSION variable:

Storing a Session Variable

<?php

session_start();

// store session data

$_SESSION['views']=1;

echo "Pageviews=". $_SESSION['views'];

?>

Destroying a Session

• if you wish to delete some session data,

you can use the unset() or the

session_destroy() function.

• The unset() function is used to free the

specified session variable:

Session

<?php

unset($_SESSION['views']); // delete single

session

?>

Or

<?php

session_destroy(); // delete all sessions

?>