PHP: checking for $_GET variables with if statements

Question

This code gets me where I need to be, but my word it is ugly.

I am checking for the existence of two $_GET variables with if() statements. I am setting the variables to empty strings first so I do not get an error when I echo them back.

$getvar1 ='';
$getvar2 ='';
$np ='';
if(isset($_GET['getvar1'])) $page_id = $_GET['getvar2'];
if(isset($_GET['getvar2'])) $route = $_GET['getvar2']; 
if(($getvar1 == '' && $getvar1 == '') || $getvar1 == '4') $np = 'np'; 
 echo "$getvar1 $getvar2 $np"; 

Is there a better way to declare the variables than setting them to empty strings?

Is there a better way to check and set the $_GET variables?

Answer 1

If it's a small app something like that would probably be better:

$getvar = isset($_GET['getvar']) ? $_GET['getvar'] : 'somedefault';

If you want to test more stuff:

$getvar = isset($_GET['getvar']) && $JUST_PUT_IT_HERE ? $_GET['getvar'] : 'somedefault';

• sMyles: Don't forget to sanitize/filter when you're pulling in data like $_GET, $_POST, $_REQUEST, etc or you could have vulnerabilities later on php.net/manual/en/function.filter-input.php

Answer 2

How about writing a function like this:

function getOrDefault($index, $default)
{
 return (!isset($_GET[$index]) || empty($_GET[$index]) ? $default : $_GET[$index]);
}
$getVar1 = getOrDefault('getvar1', '');
$getVar2 = getOrDefault('getvar2', '');

This function should be as general as possible and be located somewhere in a function-library. I don't know about the rest of your project. But for example if you do have some kind of request object (containing all information about the current (http)request), you could write specialized versions:

class Request()
{
 public function getPost($param, $default = '')
 {
 if(!isset($_POST[$param]) || empty($_POST[$param])
 {
 return $default;
 }
 return $_POST[$param];
 }
 // If param is set both in $_GET and $_POST, $_GET is return.
 public function getParam($param, $default = '')
 {
 if(!isset($_GET[$param]) || empty($_GET[$param))
 {
 return $this->getPost($param, $default);
 }
 return $_GET[$param];
 }
}
$getVar1 = $request->getParam('getVar1', '');
$getVar2 = $request->getParam('getVar2', '');

• Chris Russo: You could use $_REQUEST as well...

Answer 3

Array Merge

If you're just setting defaults, you could use array_merge():

$defaults = array(
 'getvar1' => 'default setting', //a default value
 'getvar2' => false //now you can just test
);
$params = array_merge($defaults, $_GET); //any missing elements get the default value
echo $params['getvar1']; //will output 'default setting' if $_GET['getvar1'] was not set
if($params['getvar2']){
 //do something if $_GET['getvar2'] was set to a non-false value
}

It should be noted that this only works with things like $_GET - that are already arrays. The ternary method, a getOrDefault() function, or some enigmatic logic operator code is better suited when setting defaults not already in an array.

Logic Operators

Here's an example of using logic operators (similar to using ternary operator) from the default Zend MVC index.php:

defined('APPLICATION_PATH')
 || define('APPLICATION_PATH', realpath(dirname(__FILE__) . '/../application'));

Using the question's example, it would look something like this:

isset($_GET['getvar1']) || $_GET['getvar1'] = 'default value';