Validate PHP Array Key>Value

Question

Having an array like [1]

$arr = array(
        array(
            "ignoreMe" => "123",
            "checkMe" => "value",
        ),
        array(
            "ignoreMe" => "456",
            "checkMe" => "value",
        ),
 );

I'd like to check if special keys (here the key checkMe) of the inner array have the same value. If all keys have the same value, then I'd like to remove the key from the inner array. (from all arrays)

But when having an array like [2]

$arr = array(
        array(
            "ignoreMe" => "123",
            "checkMe" => "value",
        ),
        array(
            "ignoreMe" => "456",
            "checkMe" => "value",
        ),
        array(
            "ignoreMe" => "789",
            "checkMe" => "foo", 
        ),
 );

All keys should stay intact.

How would I do this with this complex validator? (Link https://github.com/Respect/Validation)

Expected result of [1] is

$arr = array(
        array(
            "ignoreMe" => "123",
        ),
        array(
            "ignoreMe" => "456",
        ),
 );

[2] should not be touched

Here is what has been tried:

$validator = v::arr()->each(v::key("check", v::equals('value')));

Answer 1

Okay, if you are running PHP 5.5+ then you can use a combination of the array_column and array_unique functions to remove the items from the array, if they all have the same value:

I am not sure exactly what such a function would be called, so I just called it myFunc...

function myFunc(array $arr, $key)
{
    // Get all the values using a key
    $values = array_column($arr, $key);

    // Remove all duplicates
    $unique = array_unique($values);

    // If there only is one item left then it means
    // that all the values are the same, so proceed
    // with modifying it...
    if (count($unique) === 1) {

        // Go over each array...
        foreach ($arr as $x => & $value) {

            // And unset the key
            unset($value[$key]);
        }
    }
    // Return the array
    return $arr;
}

Example:

$arr1 = array(
    array("ignoreMe" => "123", "checkMe" => "value"),
    array("ignoreMe" => "456", "checkMe" => "value"),
);
$arr2 = array(
    array("ignoreMe" => "123", "checkMe" => "value"),
    array("ignoreMe" => "456", "checkMe" => "value"),
    array("ignoreMe" => "789", "checkMe" => "foo"),
);

// All the values in this array are the same, so they
// will be removed
var_dump($arr1);
var_dump(myFunc($arr1, 'checkMe'));
echo '<hr>';

// There is a value in this array that is not the same
// as the others, so this array will be left intact
var_dump($arr2);
var_dump(myFunc($arr2, 'checkMe'));