1. Lecture 6 – Form processing (Part 1) SFDV3011 – Advanced Web Development 1

2. 2 Form Parts action is the file you want to go to (could be html or php) method should be either POST or GET

3. 3 Action An action should be a URI (e.g. a file name in the current folder) or a full web address, e.g. http://www.somewebserver.com/myfile.php) Example: … This will take the user to the invoice.php page in the current directory when the user presses the submit button. Note: You should always use quotes around the URI in case it has special characters or spaces.

4. 4 Method The method can be either 'POST' or 'GET'. $_GET and $_POST are arrays built into PHP which make form processing a lot easier. Form variables are stored as keys (elements) of these arrays, indexed by their name To see what is in the array just do a var_dump() e.g. var_dump($_GET); TIP: put var_dump()at the top of form processing files so you can see what is sent from the form

5. 5 Submit Button Usually you need to have a submit button to invoke a form's action, e.g.: <input type = 'SUBMIT' name = ' the name you want to appear in the POST/GET array ' value = ' the label in the button ' >

6. 6 Example: Login

7. 7 Input types (single value) A generic input type looks like this: ' name = ' ' value = ' ' >

8. 8 The Basic Input Types Text Password Hidden Radio Checkbox Submit

9. 9 Example: Login form <?php print "logged in ". $_POST['username']; ?>

10. 10 Self-Processing Form Sometimes you want to stay on the same page when processing your forms ' method = 'post'> is the same as: 'method = 'post'> <?= is short for echo when embedding PHP in HTML You can use $PHP_SELF or $_SERVER['PHP_SELF']

11. 11 Example: Login form if( array_key_exists('submit_button', $_POST) ) { print "logged in ". $_POST['username']; } else { ?> ' method = 'post'>

12. 12 GET method … GET will show the information being passed between pages as part of the URL. – Good tool for error checking – However, it is not secure because users can see the full contents of the request. – Pages can be cached.

13. 13 POST method … POST will hide information being passed between pages in the address bar. – HINT: use GET for error checking; change to POST when submitting your work – More secure than GET – Pages won't be cached.

14. 14 Compound Types Select Text area List box Compound types enable multiple inputs and/or outputs Unlike input types, compound types always use a begin and end tag …

15. 15 Example: Login form if( array_key_exists('submit_button', $_POST) ) { print "logged in ". $_POST['username']; } else { ?> ' method = 'post'> Moe Larry Curly <input type = 'submit' name = 'submit_button' value = 'login'>

16. 16 Select Boxes Select boxes provide a drop down set of options for the user to choose from. – Value is whatever the user chooses when the submit button is pressed – If no value parameter is set, the value defaults to the label thing1 thing2 thing3

17. 17 Text Area Text Area provide a region of size row X cols to display and input text. – Value is whatever is in the area when the submit button is pressed This is some text in the text area.

18. 18 Tips and Hints Use single ' ' on the inside, " " around the outside or vice versa Take advantage of PHP by using for/while/foreach to generate multiple form elements and compound types Quotes must be used around anything with spaces

19. 19 Login program with Functions $usernames = array ( // Define valid user names and passwords 'Moe' =>'stooge1', 'Larry' => 'stooge2', 'Curly' => 'stooge3' ); // Process the login if (array_key_exists('submit_button', $_POST)) { if(process_login($usernames) == TRUE) { print "logged in ". $_POST['username']; } else { print 'Incorrect password for '.$_POST['username'].' '; display_login($usernames); } } else { display_login($usernames); }

20. 20 Display Login Function // Display a login form with a select box of usernames function display_login($users) { ?> " method = 'post'> <?php foreach ($users as $user => $pass) { print ' ’.$user.’ ’; } ?> <input type = 'submit' name = 'submit_button' value = 'login'> <?php } ?>

21. 21 Process Login Function /* checks the posted form to see if password * entered matches the password for the username *(info in $users) selected in the form. Returns * TRUE if there is a match, FALSE otherwise */ function process_login($users) { if($users[$_POST['username']] == $_POST['password']) return TRUE; else return FALSE; } Do functions simplify or complicate? Why? What are the additional benefits of using functions?