PHP. Lab. de Bases de Dados e Aplicações Web MIEIC, FEUP 2010/11. Sérgio Nunes

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1 PHP Lab. de Bases de Dados e Aplicações Web MIEIC, FEUP 2010/11 Sérgio Nunes

2 Summary Server-Side Development The PHP Language Smarty Template Engine Database Access with MDB2

3 Server-Side Development

4 Serving Static Pages 2. Send request. 3. Receive and process request. Client Web Server 1. Set URL. 6. Render and present response. 5. Send response + file's content. Hard Disk 4. Read requested file from disk.

5 Serving Dynamic Pages 2. Send request. 3. Receive and process request. Client Web Server 1. Set URL. 9. Render and present response. 8. Send response + file's content. 5. Request PHP module to process the file. Hard Disk 7. Return results. 4. Read requested file from disk. Database APIs PHP 6. Access other resources (e.g. database, APIs, etc).

6 Use Cases Process submitted form information. Manage user authentication. Interface with other services, e.g. databases, APIs, , etc.

7 Server-Side Languages There are many server-side options. As many as programming languages. Most popular: PHP, Java, ASP, C#, Perl, Python, Ruby, etc.

8 PHP

9 Brief History Originally developed by Rasmus Lerdorf in 1994 to manage his home page. Initial acronym - "Personal Home Pages". Now "PHP: Hypertext Preprocessor". Adoption and popularity due to ease of coding and wide support in web servers.

10 A PHP Script <!DOCTYPE html> <html> <head> </head> <body> <?php echo "Hello World!";?> </body> </html> After Execution <!DOCTYPE html> <html> <head> </head> <body> Hello World! </body> </html> PHP file HTML rendered

11 Features Free and open-source. Interpreted at run-time (not compiled). Weakly typed. Supports some OO concepts.

12 phpinfo Typical way to test a server installation. Lists built-in variables and settings. Lists which modules are enabled. <?php phpinfo();?> teste.php

13 Variables Variables do not need to be declared. Names start with $ and are case sensitive. Loosely typed, i.e. variable type is dynamically defined. <?php $var = 10; $var = "text"; $var2 = TRUE;?>

14 Strings String concatenation is done with "." (dot). Supports char indexing using brackets. Common functions: explode, implode, strlen, strcmp, srtpos, substr, strtolower, strtoupper, trim <?php $var = "LBAW"; print $var[1];?> # outputs "B".

15 Arrays PHP arrays are associative, i.e. they work like a hash table with (key,value) pairs. Keys and values can be of any type. <?php $array[0] = 5; $array["age"] = 22; $array["color"] = "blue"; print_r($array); $array2 = array(5, "age"=>22, "color"=>"blue"); foreach ($array as $key => $value) echo $key. "=". $value;?>

16 Classes In PHP is possible to define classes with the class keyword. Class attributes are defined with var, and class methods are defined with function. A class must be defined in a single file.

17 Class Example <?php class Test { var $name; function getname() { return $this->name; } } function sum($v1, $v2) { return $v1 + $v2; } echo Test::sum(5, 6); // Static call. $t = new Test(); $t->name = "LBAW"; echo $t->getname();?>

18 Output The print() and echo() commands can be used to output text from the PHP code. Before any output the function header() must be called to send the HTTP required headers. Also used to send HTTP error codes (e.g. 404 File Not Found). <?php header(); print("hello world!"); print("hello world!\n"); print("string inside " are interpreted - $var"); print('strings inside ' are not interpreted - $var');?>

19 Comments <?php # single-line comment // single-line comment. /* multi-line comment */?>

20 Control Structures <?php if ($var == 5) f1(); switch ($var) { case 10: f2(); break; default: f3(); }?> <?php for ($x=1; $x<10; $x++) { print $x; } while ($x > 1) { echo $x; $x--; }?>

21 Functions The function keyword is used to define functions in PHP. It is possible to define the function parameters and their default values. Functions may return values. Variables declared within the function are local. Use the global keyword to access global variables.

22 Function Example <?php $var = 3; function sum( $val=10 ) { global $var; return $val + $var; } echo sum(); // 13 echo sum(5); // 8?>

23 Includes The include() command inserts the entire contents of a given file into the PHP script. Useful for shared libraries. Fundamental for code modularity!

24 HTTP Parameters In HTTP, both POST and GET methods can handle parameters. With GET, parameters are included in the URL, e.g. With POST, parameters are included in the HTTP headers.

25 Handling Parameters Request data is available in superglobal associative arrays: $_GET contains variables passed through HTTP GET. $_POST contains variables passed through HTTP POST. $_REQUEST contains contents of $_GET and $_POST. <?php?> $_POST["name"]; $_GET["id"]; $_REQUEST["age"];

26 Session Control

27 Session Control HTTP is a stateless protocol. Each request is independent. No built-in way of handling user interactions (e.g. user authentication, shopping carts). Two standard approaches for servers to track users: cookies and sessions.

28 Cookies Client-side information storing. Cookies are pieces of data sent by web server that can be used by browsers in subsequent requests. 1. First request. Client 2. Server response + cookie. n. Other requests + cookie. Server

29 Cookies in PHP In PHP cookies are handled using the setcookie function. Cookie values are accessible in the superglobal variable $_COOKIE. bool setcookie($name [, $value [, $expire [, $path [, $domain [, $secure ]]]]]) <?php $var = "anything"; setcookie("mycookiename", $var);?> <?php echo $_COOKIE["MyCookieName"];?>

30 Sessions Server-side information storing. A unique id (session id) is assigned to each visitor. This is information is stored in cookies or propagated via URLs. Servers store session information that is accessible using the session id as key.

31 Sessions in PHP Session handling is easy in PHP. Start a session using session_start(). After this, session variables can be created or accessed using the $_SESSION variable. A session is terminated using session_destroy(). <?php session_start(); echo session_id(); $_SESSION["prefs"] = $prefs; echo $_SESSION["prefs"]; session_destroy();?>

32 Database Access with MDB2

33 PEAR MDB2 PEAR is a framework and distribution system for reusable PHP components. PEAR MBD2 is a PHP database abstraction library. It provides a common API for RDBMS accesses. Other options: ez Database, Zend ActiveRecord, Doctrine, etc.

34 Database Connection <?php require_once 'MDB2.php'; // Data Source Name: This is the universal connection string $dsn = array( 'phptype' => 'pgsql', 'username' => 'someuser', 'password' => 'apasswd', 'hostspec' => 'localhost', 'database' => 'thedb',); $options = array( 'debug' => 2, 'portability' => MDB2_PORTABILITY_ALL,); // uses MDB2::factory() to create the instance and also attempts to connect to the host $mdb2 =& MDB2::connect($dsn, $options); if (PEAR::isError($mdb2)) { die($mdb2->getmessage()); } [...] // close connection $mdb2->disconnect();?>

35 Query Execution <?php [...] // Create a valid MDB2 object named $mdb2 at the beginning of your program require_once 'MDB2.php'; $mdb2 =& MDB2::connect('pgsql://usr:pw@localhost/dbnam'); if (PEAR::isError($mdb2)) { die($mdb2->getmessage()); } // Proceed with a query... $sql = 'SELECT * FROM clients where =? and address =?'; $data= array($ , $address)); $result =& $mdb2->query($sql, $data); // Always check that result is not an error if (PEAR::isError($result)) { die($result->getmessage()); } // Get each row of data on each iteration until there are no more rows while (($row = $res->fetchrow())) { // Assuming MDB2's default fetchmode is MDB2_FETCHMODE_ORDERED echo $row[0]. "\n"; }?>

36 Fetch Associative Arrays <?php $res = $db->query('select id, name, FROM users'); $row = $db->fetchrow($res, MDB_FETCHMODE_ASSOC); /* $row will contain: array ( 'id' => <column "id" data>, 'name' => <column "name" data>, ' ' => <column " " data> ) */ // Access the data with: $id = $row['id']; // $id = $row[0]; $name = $row['name']; // $name = $row[1]; $ = $row[' ']; // $ = $row[2];?>

37 Fetch by Number <?php [...] // the row to start fetching $from = 50; // how many results per page $respage = 10; // the last row to fetch for this page $to = $from + $respage; foreach (range($from, $to) as $rownum) { if (!$row = $db->fetchinto($res, $fetchmode, $rownum)) { break; } $id = $row['id']; // $id = $row[0]; [...] }?>

38 Insert & Update <?php // Once you have a valid MDB2 object named $mdb2... $sql = "INSERT INTO clients (id, name, address) VALUES ($id, $name, $address)"; $affected =& $mdb2->exec($sql); // Always check that result is not an error if (PEAR::isError($affected)) { die($affected->getmessage()); }?> <?php // Once you have a valid MDB2 object named $mdb2... $sql = 'UPDATE clients SET name =?, address =? WHERE id =?'; $types = array('text', 'text','integer'); $sth =& $mdb2->prepare($sql, $types, MDB2_PREPARE_MANIP); $res =& $sth->execute(array($name, $address, $id)); if (PEAR::isError($res)) die($res->getdebuginfo());?>

39 Smarty Template Engine

40 Smarty Smarty is a template engine for PHP. Enables separation between presentation layer and business logic layer. PHP was originally designed to be included in HTML files. Can easily lead to code repetition and lower readability. Harder to maintain. Different type of work can easily be separated (e.g. design vs. programming).

41 Smarty PHP file html Browser php & html code PHP file vars Smarty Template file html Browser php code html code

42 Smarty Example <?php include_once('smarty.class.php'); $smarty = new Smarty; [...] $smarty->assign('s_userid', $s_userid); $smarty->assign('s_username', $s_username); $smarty->assign('s_usertype', $s_usertype); $smarty->display('index.tpl');?> index.php hello {$s_username}, glad to see you login with user {$s_userid}. you have privileges of {$s_usertype}. index.tpl

43 Associative Arrays <?php $smarty->assign('contacts', array('fax' => ' ', ' ' => 'phone' => array('home' => ' ', 'cell' => ' ') ) ); $smarty->display('index.tpl');?> index.php {$Contacts.fax} {$Contacts. } {* you can print arrays of arrays as well *} {$Contacts.phone.home} {$Contacts.phone.cell} index.tpl

44 Common Features {include file="header.tpl" title="my Title"} includes {foreach item=user from=$users} {foreach key=type item=contact from=$user} {$type}: {$contact} {/foreach} {/foreach} foreach {if $type eq 2} {$name} {/if} ifs

45 Application Structure

46 User Pages PHP file include base files get data with MDB2 present with Smarty

47 Action Pages PHP file include base files get data with MDB2 redirect

48 Application Files /<webapp> PHP files. /lib Required libraries (e.g. Smarty, MBD2, etc.). /includes DB, Smarty and session setup. /database DB access files. A file per class per entity. /templates Smarty template files. /templates_c Smarty cache.

49 Example <? require_once('includes/base.php'); require_once('database/avioesmodelos.php'); $nome = $_GET["nome"]; $modelo = $_GET["modelo"]; $avioes = AvioesModelos::getByNomeModelo($nome, $modelo);?> $smarty->assign("avioes", $avioes); $smarty->display('listaravioes.tpl'); listaravioes.php

$php'); if ($_POST['nome'] == "") $_SESSION['s_errors']['nome'] = 'O nome não pode ser vazio'; if ($_SESSION['s_errors']) { $_SESSION["s_values"] = $_POST; header("location: ".$

50 Example <? require_once('includes/base.php'); require_once('database/avioes.php'); if ($_POST['nome'] == "") $_SESSION['s_errors']['nome'] = 'O nome não pode ser vazio'; if ($_SESSION['s_errors']) { $_SESSION["s_values"] = $_POST; header("location: ". $_SERVER['HTTP_REFERER']); die; } if ($s_tipo!= 'admin') {header("location: index.php");die;} $nome = $_POST['nome']; $codmodelo = $_POST['codmodelo']; $errors = Avioes::insert($nome, $codmodelo);?> if ($errors) { $_SESSION["s_errors"] = $errors; $_SESSION["s_values"] = $_POST; header("location: ". $_SERVER['HTTP_REFERER']); } else { $_SESSION["s_messages"][] = "Avião Criado com Sucesso"; header("location: veraviao.php?codaviao=". Avioes::getLastInsertedId()); } accaonovoaviao.php

51 PHP.net Main PHP site Central documentation source. Supports user comments. Includes tutorials and also pointers to external resources.

52 References PHP.net PEAR MDB2 Smarty PHP Template Engine

PHP INTERVIEW QUESTION-ANSWERS

PHP INTERVIEW QUESTION-ANSWERS 1. What is PHP? PHP (recursive acronym for PHP: Hypertext Preprocessor) is the most widely used open source scripting language, majorly used for web-development and application development and can be embedded