A $_GET input parameter that is an Array

Question

I'm trying to pass 3 parameter to a script, where the 3rd parameter $_GET['value3'] is supposed to be an array

$_GET['value1'] 
$_GET['value2'] 
$_GET['value3'] //an array of items

I'm calling the script like this: (notice my syntax for value3, I'm not sure it's correct)

http://localhost/test.php?value1=test1&value2=test2&value3=[the, array, values]

I then use a foreach to hopefully loop through the third parameter value3 which is the array

//process the first input $_GET['value1']

//process the second input $_GET['value2']

//process the third input $_GET['value3'] which is the array
foreach($_GET['value3'] as $arrayitem){
    echo $arrayitem; 
}

but I get the error Invalid argument supplied for foreach()

I'm not sure if my methodology is correct. Can some clarify how you'd go about doing the sort of thing

Answer 1

There is no such thing as "passing an array as a URL parameter" (or a form value, for that matter, because this is the same thing). These are strings, and anything that happens to them beyond that is magic that has been built into your application server, and therefore it is non-portable.

PHP happens to support the &value3[]=the&value3[]=array&value3[]=values notation to automagically create $_GET['value3'] as an array for you, but this is special to PHP and does not necessarily work elsewhere.

You can also be straight-forward and go for a cleaner URL, like this: value3=the,array,values, and then use explode(',', $_GET['value3']) in your PHP script to create an array. Of course this implies that your separator char cannot be part of the value.

To unambiguously transport structured data over HTTP, use a format that has been made for the purpose (namely: JSON) and then use json_decode() on the PHP side.

Answer 2

try

http://localhost/test.php?value1=test1&value2=test2&value3[]=the&value3[]=array&value3[]=values