introduction to php –part.2

Introduction to PHP – Part.2Chapter 9 from text book

1

Outline

Form Handling

Files

Cookies

Session Tracking

Database Accesses using PHP and MySQL

(13.5)

Content management system

2

Submitting data to a web server

Though browsers mostly retrieve data, sometimes you want to submit data to a server◦ Hotmail: Send a message

◦ Flickr: Upload a photo

◦ Google Calendar: Create an appointment

The data is sent in HTTP requests to the server◦ with HTML forms

The data is placed into the request as parameters

3

"Superglobal" Arrays

Array Description

$_GET, $_POST Parameters passed to GET and POST requests

$_SESSION,

$_COOKIE

"cookies" used to identify the user (seen later in this

chapter)

4

• PHP superglobal arrays contain information about

the current request, server, etc.:

• These are special kinds of arrays called

associative arrays.

Using $_GET

5

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

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

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

<input type="submit" />

</form>

• If the user enters his information then clicks the "Submit"

button, the URL sent to the server could look something like

this:

-http://~~~/welcome.php?fname=Deema&age=3

• Processing data in "welcome.php" file:

Welcome <?php print $_GET["fname"]; ?>.<br />

You are <?php echo $_GET["age"]; ?>years old!

Checkpoint 1

What are the changes in the previous

example if you use $_POST instead of

$_GET?

6

Files

PHP can:

◦ Deal with any files on the server

◦ Deal with any files on the Internet, using either http or ftp

PHP associates a variable with a file, called the file variable (for

program reference)

A file has a file pointer (where to read or write)

◦ $fptr = fopen(filename, use_indicator)

Use indicators:

r read only, from the beginning

r+ read and write, from the beginning

w write only, from the beginning (also creates the file, if necessary)

w+ read and write, from the beginning (also creates the file, if necessary)

a write only, at the end, if it exists (creates the file, if necessary)

a+ read and write, read at the beginning, write at the end

Reading files

1) Read all or part of the file into a string variable

$str = fread(file_var, #bytes)

To read the whole file, use filesize(file_name) as the second parameter

2) Read all of the lines of the file into an array

@file_lines = file(file_name)

Need not open or close the file

3) Read one line from the file

$line = fgets(file_var, #bytes)

Reads characters until eoln, eof, or #bytes- characters have been read

4) Read one character at a time

$ch = fgetc(file_var)

Writing to files

$bytes_written = fwrite(file_var, string)

◦ fwrite returns the number of bytes it wrote

Files can be locked (to avoid interference

from concurrent accesses) with flock

Cookies

HTTP is a stateless protocol, that is, the server treats each request as completely separate from any other

The mechanism of cookies can be used to help maintain state by storing some information on the browser system

A cookie is a key/value pair that is keyed to the domain of the server

◦ This key/value pair is sent along with any request made by the browser of the same server

A cookie has a lifetime which specifies a time at which the cookie is deleted from the browser

10

Cookies

PHP Support for Cookies

PHP provides the setcookie function to

set a cookie in a response

◦ The first parameter is the cookie’s name

◦ The second, optional, parameter gives the cookie’s

value

◦ The third, optional, parameter gives the expiration

The cookie must be set before setting content

type and before providing any other output

The $_COOKIES array provides access to

cookies in the HTTP request

12

Cookies Example

Example 1: Writing Cookies to the client’s

machine.

Example 2: The server reads the written

cookies from the client’s machine.

13

Example 1: Writing Cookies

(cookies.html)<html xmlns = "http://www.w3.org/1999/xhtml">

<head> <title>Writing a cookie to the client computer</title> </head>

<body style = "font-family: arial, sans-serif; background-color: #99CCFF">

<h2>Click Write Cookie to save your cookie data.</h2>

<form method = "post" action = "cookies.php“>

<strong>Name:</strong><br />

<input type = "text" name = "NAME" /><br />

<strong>Height:</strong><br />

<input type = "text" name = "HEIGHT" /><br />

<strong>Favorite Color:</strong><br />

<input type = "text" name = "COLOR" /><br />

<input type = "submit" value = "Write Cookie"

style = "background-color: #F0E86C; color: navy; font-weight: bold"

/></p>

</form> </body></html> 14

Example 1: Writing Cookies

(cookies.php)<?php

extract( $_POST );

// write each form field’s value to a cookie and set the cookie’s expiration date

setcookie( "Name", $NAME, time() + 60 * 60 * 24 * 5 );

setcookie( "Height", $HEIGHT, time() + 60 * 60 * 24 * 5 );

setcookie( "Color", $COLOR, time() + 60 * 60 * 24 * 5 );

?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns = "http://www.w3.org/1999/xhtml">

<head> <title>Cookie Saved</title> </head>

<body style = "font-family: arial, sans-serif">

<p>The cookie has been set with the following data:</p>

<br /><span style = "color: blue">Name:</span>

<?php print( $NAME ) ?><br />

<span style = "color: blue">Height:</span>

<?php print( $HEIGHT ) ?><br />

<span style = "color: blue">Favorite Color:</span>

<span style = "color: <?php print( "$COLOR\">$COLOR" ) ?> </span><br />

<p>Click <a href = "readCookies.php">here</a> to read the saved cookie.</p>

</body> </html> 15

Example 2: Reading Cookies

(readcookies.php)<html xmlns = "http://www.w3.org/1999/xhtml">

<head><title>Read Cookies</title></head>


<p>

<strong> The following data is saved in a cookie on your computer. </strong>

</p>

<table border = "5" cellspacing = "0" cellpadding = "10">

<?php

// iterate through array $_COOKIE and print name and value of each cookie

foreach ( $_COOKIE as $key => $value )

print( "<tr>

<td bgcolor=\"#F0E68C\">$key</td>

<td bgcolor=\"#FFA500\">$value</td>

</tr>" );

?>

</table> </body> </html>16

Sessions

Some applications need to keep track of a session

Sessions are represented internally in PHP with a session id

◦ A session consists of key/value pairs

A session can be initialized or retrieved by using the session_start function

◦ This function retrieves $_SESSION, an array containing the key/value pairs for each session in the current request

Example:

17

<?php

// this starts the session

session_start();

// this sets variables in the session

$_SESSION['test']='testing';

print "Done";

?>

Sessions

Example

Set a session variable using $_SESSION

array.

Checkpoint 2

What is the difference between Sessions

and Cookies?

Can we use Sessions and Cookies in the

same PHP program?

Database Accesses using PHP and

MySQL

To access data stored in a MySQL database:

1. Create a Connection to a MySQL DBMS

21

$con = mysql_connect(servername,username,password);

2. Select a specific DB:

3. Send your query to MySQL to execute it:

4. Iterate through the returned array:

mysql_select_db(DB_name, $con);

$result = mysql_query(your_SQL_stmt);

Mysql_close($con);

$row = mysql_fetch_row($result)

5. Close the connection to MySQL

Example : Connecting to a DB

(data.html)<html xmlns = "http://www.w3.org/1999/xhtml">

<head> <title>Sample Database Query</title> </head>

<body style = "background-color: #F0E68C">

<h2 style = "font-family: arial color: blue“> Querying a MySQL database. </h2>

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

<p>Select a field to display:



<select name = "select">

<option selected = "selected">*</option>

<option>ID</option>

<option>Title</option>

<option>Category</option>

<option>ISBN</option>

</select> </p>

<input type = "submit" value = "Send Query"

style = "background-color: blue; color: yellow; font-weight: bold" />

</form> </body></html>

22


(database.php)<html xmlns = "http://www.w3.org/1999/xhtml">

<head> <title>Search Results</title> </head>


<?php

extract( $_POST );

// build SELECT query

$query = "SELECT " . $select . " FROM Books";

// Connect to MySQL

if ( !( $database = mysql_connect( "localhost",

"root", "" ) ) )

die( "Could not connect to database" );

// open Products database

if ( !mysql_select_db( "Products", $database ) )

die( "Could not open Products database" );

// query Products database

if ( !( $result = mysql_query( $query, $database ) ) ) {

print( "Could not execute query! <br />" );

die( mysql_error() );

}

?>

23


(database.php)<h3 style = "color: blue"> Search Results</h3>

<table border = "1" cellpadding = "3" cellspacing = "2” >

<?php

// fetch each record in result set

for ( $counter = 0;

$row = mysql_fetch_row( $result ); s $counter++ ){

// build table to display results

print( "<tr>" );

foreach ( $row as $key => $value )

print( "<td>$value</td>" );

print( "</tr>" );

}

mysql_close( $database );

?>

</table> <br />Your search yielded <strong>

<?php print( "$counter" ) ?> results.<br /><br /></strong>

</body> </html>

24

Remaining (self study)

Sorting Arrays

my_sql_num_rows()

my_sql_num_fields()

my_sql_num_rows()

my_sql_fetch_array()

25

CONTENT MANAGEMENT SYSTEMS (CMS)

Extra Topic

What is CMS?

A Web Content

Management System

(WCMS) is a software system

which provides website

authoring, collaboration and

administration tools designed to

allow users with little

knowledge of web programming

languages or markup languages

to create and manage the site's

content with relative

ease.(Wikipedia, 2010)

What functionalities do CMSs

provide? WYSIWYG editor for

content

Easily editable content

Multilingual front end

Multi-

Template/Themes.

Seamless Database

connectivity

Scalable feature sets

…. And much more!!

How do I choose a CMS?

Understanding Your Web Content

Determining and documenting "business"

requirements

OS that runs on

Type of Database

Extendibility

User Friendly

Provides templating that is completely

customizable and Supports XHTML and

CSS templates

Example (Joomla)

Example (Drupal)

THE END

introduction to php –part.2

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