Modify empty keys in associative array in php

i have a really long form in wordpress that it filled out by the user and then submitted to a thirdparty crm via API.

The thing is if user doesn’t fill a field, these field will be false or empty and remote_post will fail.

I tried to add a custom value to empty fields with a foreach but they are in associative array and i dont know how to modify it.

This is my code so far (i changed values but is the same structure):

$body = [
'array1' => [
'key1' => user(value),
'key2' => user(value),
'key3' => user(value),
    ],

'array2' => [
'key1' => user(value),
'key2' => user(value),
'key3' => user(value),
    ],

'array3' => [
[   
'key1' => user(value),
'key2' => user(value),
'key3' => user(value),
],
[   
'key1' => user(value),
'key2' => user(value),
'key3' => user(value),
],
    ],

'array4' => [
    'subarrray1' => [
     'key1' => user(value),
     'key2' => user(value),
     'key3' => user(value),
    ],
    'subarray2' => [
     'key1' => user(value),
     'key2' => user(value),
     'key3' => user(value),
    ],
],

];

//this work only with some arrays and only change value inside the second array
foreach($body as $row => $innerArray){
    foreach($innerArray as $key => $value){
        if ( empty($value) ) $value = 'empty o whatever';
    } 
}

Answer

You can use recursion

$body = [
    'array1' => [
        'key1' => 123,
        'key2' => '',
        'key3' => '',
    ],

    'array2' => [
        'key1' => '',
        'key2' => '',
        'key3' => 123,
    ],

    'array3' => [
        [
            'key1' => '',
            'key2' => '',
            'key3' => '',
        ],
        [
            'key1' => '',
            'key2' => '',
            'key3' => 123,
        ],
    ],

    'array4' => [
        'subarrray1' => [
            'key1' => '',
            'key2' => 123,
            'key3' => '',
        ],
        'subarray2' => [
            'key1' => '',
            'key2' => '',
            'key3' => '',
        ],
    ]
];


function replace_empty(&$arr) {
    if(is_iterable($arr)) {
        foreach ($arr as &$row) {
            replace_empty($row);
        }
    } elseif (empty($arr)) {
        $arr = 'empty o whatever';
    }
}

replace_empty($body);

var_dump($body);