Can this be done? [PHP]

JonD

JonD

JonD

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On my pages i usually do a big if/else/switch to decide which function to call

PHP: 
if ($_GET['action'] == 'whatever')
  doThis();
else if ($_GET['action'] == 'bob')
  doThis2();

Is it possible to do sumthing like this:

$action['whatever'] = doThis();
$action['bob'] = doThis2();

Then how would I call the appropiate function to be called depending on the value of $_GET['action']?

Is it possible?

Is there another way to do what I want with less/tidy/efficient code?

Thx
 
Ok i found a way, however if $_GET['action'] isnt set or is set to a value that is not in the array then i recieve an error. How could I get around this?

Again this may not be the best way to do it so if anyone has another method, please share. :D

PHP: 
function login() { } 
function logout() { }
function registrationForm() { }

$_action['login']    = 'login';
$_action['logout']   = 'logout';
$_action['register'] = 'registrationForm';

call_user_func($_action[$_GET['action']]);

Thx
 
1st method. Only thing that changes is the last if statement.
PHP: 
if(isset($_GET['action'])){
  $action = $_GET['action'];
}

if($action == "whatever"){
  DoThisFunction();
}
elseif($action == "me"){
  ExecuteMe();
}

2nd method
PHP: 
if($action){
  DoThisFunction($action);
}
 
If you've got a large block of if/else statements with fixed values to compare to, always go with a switch statement for efficiency. Its faster since PHP doesn't need to evaluate evaluate every conditional once a statement returns true. For further efficiency, put the most commonly executed cases at the top so it has fewer lines of code to run through in most executions.

Code: 
<?php
switch ($_GET['action']) {
case 'login':
   login();
   break;
case 'logout':
   logout();
   break;
default:
   echo 'Hello new user';
}
?>

default is the fallback block used when no case matches.

/edit - Also, when using isset() as Beansprout mentioned, opt for a ternary operator for more concise code:
Code: 
$action = isset($_GET['action']) ? $_GET['action'] : null;
Neater than an if/else. Though I'd use an !empty() instead of isset() as you only really want to act on valid values for $_GET['action'].
 
Last edited:
Augmented's example is much preferred, however this is a sneaky chance to introduce function_exists :)

Code: 
<?php

if ((isset($_GET['action'])) && (function_exists($_GET['action']))) {
    call_user_func($_GET['action']);
} else {
    DefaultFunction();
}

?>


EDIT:

On the note of concise.. you can use variable functions and void the need to use call_user_func() at all:
http://us2.php.net/manual/en/functions.variable-functions.php
Code: 
<?php

@$_GET['action']();

?>
but that is just .. meh, as far as good practice goes :)
 
Last edited:
But then what happens if I request /foo.php?action=bulkEmail() or similar?

Though good app design would prevent that, I'd filter it through an array of predefined actions with in_array() or a switch.

Augmented - hehheh depends if he'll ever use 0 though, so I reckoned isset() was better to show him generally (the notes on the PHP page are great) :)
 
Beansprout said:
But then what happens if I request /foo.php?action=bulkEmail() or similar?

Though good app design would prevent that, I'd filter it through an array of predefined actions with in_array() or a switch.

Augmented - hehheh depends if he'll ever use 0 though, so I reckoned isset() was better to show him generally (the notes on the PHP page are great) :)
Click to expand...
It was a quick example to introduce function_exists(), that is all. I'm lazy and cba to type out a filter when I've already said Augmented's switch() example is better.
 
Ill have a look at the in_array() and isset() stuff.

Id know i could do it with if/else/switches but I find the code quite ugly and hard to organise etc, which is why I thought the array idea would be good.

---

The following method seems to work, can anyone spot a time where it will fail?

PHP: 
$_action = array (
	''         => 'login',
	'login'    => 'login',	
	'logout'   => 'logout',	
	'register' => 'registerForm'
);	

if (array_key_exists($_GET['action'], $_action))
	call_user_func($_action[$_GET['action']]);
else
	header("Location: index.php");

Thx
 
Last edited:
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