PHP array_filter with argument to callback

Question

I need to filter an array in PHP but am not sure how to pass an argument to the callback. Essentially I have 2 comparisons to make on each item in the array.

// This data will be sent to the function as JSON so I'm "creating" the JSON here.
$data = json_encode(Array(
    Array("StartDate"=>"2014/07/31","LocZipCode"=>"19406","LocationURL"=>"FSU","EventType"=>"UN"),
    Array("StartDate"=>"2014/08/31","LocZipCode"=>"23513","LocationURL"=>"FSU","EventType"=>"UN"),
    Array("StartDate"=>"2014/07/31","LocZipCode"=>"92108","LocationURL"=>"BU","EventType"=>"UN"),
    Array("StartDate"=>"2014/09/30","LocZipCode"=>"78661","LocationURL"=>"BU","EventType"=>"UN")
));

// even using a global variable doesn't 
// make it visible in getUniv() function
global $univ_seg;
$univ_seg = 'FSU';

getUA($data, $univ_seg);

function getUniv($var){
    return($var["EventType"] == "UN" && $var["LocationURL"] == $univ_seg);
}

function getUA($data, $univ_seg) {
    $univ_sched = json_decode($data, true);
    $re = array_filter($univ_sched, "getUniv");
    print_r($re); 
}

I've also tried using a lambda but I just can't make it work. Any ideas??

If you want to make that variable global to your `getUniv()` function, place the global statement inside the function. — showdev, Jul 29 '14 at 22:22

score 5 · Answer 1 · edited Jul 29 '14 at 22:39

// even using a global variable doesn't 
// make it visible in getUniv() function
global $univ_seg;
$univ_seg = 'FSU';

That's not how globals work - to access a global variable, you need a matching global declaration in the each scope you want to use it in.

function getUniv($var){
    global $univ_seg;
    return($var["EventType"] == "UN" && $var["LocationURL"] == $univ_seg);
}

This would work better as an anonymous function, though:

$re = array_filter($univ_sched, function getUniv($var) use ($univ_seg) {
    return($var["EventType"] == "UN" && $var["LocationURL"] == $univ_seg);
});

Machavity · Answer 2 · 2014-07-29T22:28:50.447

0

Why not try it with an anonymous function instead? I find callbacks work better with that

function getUA($data, $univ_seg) {
    $univ_sched = json_decode($data, true);
    $re = array_filter($univ_sched, function($var){
        return($var["EventType"] == "UN" && $var["LocationURL"] == 'FSU');
    });
    print_r($re); 
}

edited Jul 29 '14 at 22:28

answered Jul 29 '14 at 22:22

Machavity

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You need `use` like ...`function($var) use($univ_seg) {` – Yoshi Jul 29 '14 at 22:23
If you're going to be calling it in more than one place, it would make sense to use a function. – Jared Farrish Jul 29 '14 at 22:23
@Yoshi Not in this case. [See example 1 here](http://php.net/manual/en/functions.anonymous.php) – Machavity Jul 29 '14 at 22:26
@JaredFarrish While that's true, it's also uncommon and the OP doesn't show the function used anywhere but as a callback. – Machavity Jul 29 '14 at 22:27
Without `use` `$univ_seg` will be undefined inside the callback to `array_filter`. Currently you'll get an `Notice: Undefined variable: univ_seg` warning. http://3v4l.org/iTuco – Yoshi Jul 29 '14 at 22:33
Well, using `global` certainly isn't a better option. – Jared Farrish Jul 29 '14 at 22:35

score 0 · Accepted Answer · answered Jul 29 '14 at 22:31

I got it to work using an object, http://www.php.net/manual/en/language.pseudo-types.php#language.types.callback

class univFilter {
    public $univ_seg;
    public function filter($var) {
        if($var["EventType"] == "UN" && $var["LocationURL"] == $this->univ_seg)
            return true;
          else
            return false;
    }
}

$data = json_encode(Array(
    Array("StartDate"=>"2014/07/31","LocZipCode"=>"19406","LocationURL"=>"FSU","EventType"=>"UN"),
    Array("StartDate"=>"2014/08/31","LocZipCode"=>"23513","LocationURL"=>"FSU","EventType"=>"UN"),
    Array("StartDate"=>"2014/11/30","LocZipCode"=>"92108","LocationURL"=>"BU","EventType"=>"UN"),
    Array("StartDate"=>"2014/09/30","LocZipCode"=>"78661","LocationURL"=>"BU","EventType"=>"UN")
));

$univ_seg = "BU";
getUA($data,$univ_seg);

function getUA($data, $univ_seg) {
    $f = new univFilter();
    $f->univ_seg = $univ_seg;
    $univ_sched = json_decode($data, true);
    $data       = array_filter($univ_sched,array($f,"filter"));
    print_r($data);
}

what if there were 2 params you needed to pass – Muhammad Omer Aslam Feb 03 '20 at 01:24 — Muhammad Omer Aslam, Feb 03 '20 at 01:24

Jared Farrish · Answer 4 · 2014-07-29T22:45:57.870

You could use a lambda function:

$data = json_encode(Array(
    Array("StartDate"=>"2014/07/31","LocZipCode"=>"19406","LocationURL"=>"FSU","EventType"=>"UN"),
    Array("StartDate"=>"2014/08/31","LocZipCode"=>"23513","LocationURL"=>"FSU","EventType"=>"UN"),
    Array("StartDate"=>"2014/07/31","LocZipCode"=>"92108","LocationURL"=>"BU","EventType"=>"UN"),
    Array("StartDate"=>"2014/09/30","LocZipCode"=>"78661","LocationURL"=>"BU","EventType"=>"UN")
));

$univ_seg = 'FSU';

getUA($data, $univ_seg);

function getUnivFunc($univ_seg){
    return create_function('$a','return $a["EventType"] == "UN" && $a["LocationURL"] == "' . $univ_seg . '";');
}

function getUA($data, $univ_seg) {
    $univ_sched = json_decode($data, true);
    $re = array_filter($univ_sched, getUnivFunc($univ_seg));
    print_r($re); 
}

http://codepad.org/LnVVry5L

Gives:

Array
(
    [0] => Array
        (
            [StartDate] => 2014/07/31
            [LocZipCode] => 19406
            [LocationURL] => FSU
            [EventType] => UN
        )

    [1] => Array
        (
            [StartDate] => 2014/08/31
            [LocZipCode] => 23513
            [LocationURL] => FSU
            [EventType] => UN
        )

)

PHP array_filter with argument to callback

4 Answers4

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