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Feb

4

Variable function calls

By mike@mike-miles.com

When using AJAX or sending vaiables to a PHP page to run a function there is a nice peice of code I like to put at the top of the PHP page.  It is a peice of code that I use to run a function by passing its name through a variable. This allows you to GET or POST to a page many times and preform multiple functions. Here is the code and I’ll explain a bit more of a few ways that you can use it;

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<?PHP 
	//if passed the variable 'function' through GET or POST 
	if($function = $_REQUEST['function']){ 
		//if function exists, run function 
		if(function_exitst($function)) $function(); 
		//else show error 
		else echo 'Error: function '',$function,'()' does not exist.'; 
		//Exit script
		exit; 
	} 
?>

So to reiterate this is what this function does.

If the page is passed the varaible ‘function’ (either through GET or POST, hence the $_REQUEST) then it knows to run a function on the page.

It’ll then set the passed variable to the $function variable, and test to see if the function exists (by using PHP’s function_exists() function)

If the function does exists, the code then calls if ($function();), else it’ll show an error.

for example you could use this code like so;

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<?PHP 
	//if passed the variable 'function' through GET or POST 
	if($function = $_REQUEST['function']){ 
		if(function_exitst($function)) $function(); 
		else echo 'Error: function '',$function,'()' does not exist.'; 
		exit; 
	} 
 
	function submitForm(){ 
		$value = $_POST['field1']; 
		echo 'You inputed ',$value,'.'; 
	} 
?> 
<html>  
	<head>  
		<title>Sample</title>  
	</head>  
	<body> 
		<form action="<?= $_SERVER['PHP_SELF']; ?>?function='submitForm'" method="POST">  
			<input name="field1" type="text" />  
			<input type="submit" value="submit" />  
		</form>  
	</body> 
</html>

So the form will submit to itself, and run the function ’submitForm’ when it does so.  Of course this is a very simple example.

you can download the complete version of this code, on my code page

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Filed under: PHP, code