PHP - array_diff_key() returning results on duplicate values rather than keys?

Question

I made this function to check for expected request variables. It was working great until I realized that if two values (Not keys) were the same, it would return a positive number as though a key was missing. Consider the following code:

function requestCheck($expectedAr)
{
    if(isset($_GET) && isset($_POST))
    {
        $requestAr = array_unique(array_merge($_GET, $_POST));
    }elseif(isset($_GET)){
        $requestAr = $_GET;
    }elseif(isset($_POST)){
        $requestAr = $_POST;
    }else{
        $requestAr = array();
    }
    $diffAr = array_diff_key(array_flip($expectedAr),$requestAr);
    if(count($diffAr) > 0)
    {
        returnError("Missing variables: ".implode(',',array_flip($diffAr)).".");
    }else {
        return $requestAr;
    }
}

$requestAr = requestCheck(['name','password']);

if 'name' and 'password' both hold the same value, it will run returnError(). Not seeing why.

Here's a dump of $_POST:

array (
  'poolName' => 'xpool',
  'userPrefix' => 'xpool'
)

Can you add some sample input arrays using var_export to dump them? — Matt
– Matt, Commented Apr 3, 2017 at 15:38

apokryfos · Accepted Answer · 2017-04-03 15:57:41Z

1

array_unique will strip unique values so you'll end up with either name or password but not both.

Solution:

function requestCheck($expectedAr) {
    if(isset($_GET) && isset($_POST)) {
        $requestAr = $_REQUEST;
    }elseif(isset($_GET)) {
        $requestAr = $_GET;
    }elseif(isset($_POST)) {
        $requestAr = $_POST;
    }else{
        $requestAr = array();
    }
    $diffAr = array_diff_key(array_flip($expectedAr),$requestAr);
    if(count($diffAr) > 0)
    {
        returnError("Missing variables: ".implode(',',array_flip($diffAr)).".");
    }else {
        return $requestAr;
    }
}

$requestAr = requestCheck(['name','password']);

I think it's safe to also do the following:

function requestCheck($expectedAr) {

    $requestAr = isset($_REQUEST) && is_array($_REQUEST)?$_REQUEST:array();        
    $diffAr = array_diff_key(array_flip($expectedAr),$requestAr);

    if(count($diffAr) > 0)  {
        returnError("Missing variables: ".implode(',',array_flip($diffAr)).".");
    }else {
        return $requestAr;
    }
}

$requestAr = requestCheck(['name','password']);

edited Apr 3, 2017 at 15:57

answered Apr 3, 2017 at 15:45

apokryfos

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8 Comments

apokryfos Over a year ago

@xendi keys are unique by default. You can't have an array with the same key multiple times.

xendi Over a year ago

Well, I was combining post and get in case someone had sent it via both by mistake, I could accept it anyway. I was told to not use request for some reason. I think because it contains more than get and post. I'd run into an error using request before. Maybe with some reserved word.

apokryfos Over a year ago

@xendi $_REQUEST is more or less the same thing as combining the 2 (also includes cookies in there though).

xendi Over a year ago

Yeah, I think it was a session variable that was colliding, causing an error that lead me to stop using request.

xendi Over a year ago

array_intersect_key() will fix it.

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