Php array_filter not accessing array value by Key

Question

So The below code works as expected and filters out null values and string "undefined" I was getting in my request

$search_params = array_filter(
                    $search_params,
                    function ($val, $key) {
                        return (isset($val) && $val != 'undefined');
                    },
                    ARRAY_FILTER_USE_BOTH
                );

But when I try to do below the function never returns the filtered array e.g always false is returned

$search_params = array_filter(
                    $search_params,
                    function ($val, $key) {
                        return (isset($search_params[$key]) && $val != 'undefined');
                    },
                    ARRAY_FILTER_USE_BOTH
                );

I was wondering what is causing this behavior, is this some kind of context thing?

score 2 · Accepted Answer · answered Dec 26 '21 at 21:36

2

The global variable $search_params is not in scope inside the function. Use the use() directive to indicate variables that should be inherited into the function's scope.

$search_params = array_filter(
    $search_params,
    function ($val, $key) use ($search_params) {
        return (isset($search_params[$key]) && $val != 'undefined');
    },
    ARRAY_FILTER_USE_BOTH
);

answered Dec 26 '21 at 21:36

Barmar

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Thanks, mate, worked like a charm. I will accept the answer in 7 minutes because God knows what validation :D – IrfanAnwar Dec 26 '21 at 21:41

score 1 · Answer 2 · answered Dec 26 '21 at 21:43

Your $search_params is not available within the callback function. You must explicitly pass it with use

$search_params = array_filter(
    $search_params,
    function ($val, $key) use ($search_params) {
        return (isset($search_params[$key]) && $val != 'undefined');
    },
    ARRAY_FILTER_USE_BOTH
);

As of PHP 7.4 you may use arrow functions, which have access to the above scope:

$search_params = array_filter(
    $search_params,
    fn ($val, $key) => isset($search_params[$key]) && $val != 'undefined',
    ARRAY_FILTER_USE_BOTH
);

Php array_filter not accessing array value by Key

2 Answers2