compare object properties and show diff in PHP

Something like the following, which iterates through and does a recursive diff is the item in the array is itself an array could work:

Des similar work to array_diff, but it does a check to see if it is an array first (is_array) and if so, sets the diff for that key to be the diff for that array. Repeats recursively.

function recursive_array_diff($a1, $a2) { 
    $r = array(); 
    foreach ($a1 as $k => $v) {
        if (array_key_exists($k, $a2)) { 
            if (is_array($v)) { 
                $rad = recursive_array_diff($v, $a2[$k]); 
                if (count($rad)) { $r[$k] = $rad; } 
            } else { 
                if ($v != $a2[$k]) { 
                    $r[$k] = $v; 
                }
            }
        } else { 
            $r[$k] = $v; 
        } 
    } 
    return $r; 
}

It then works like this:

$obj1 = new StdClass; $obj1->prop = array(1,2);
$obj2 = new StdClass; $obj2->prop = array(1,3);
print_r(recursive_array_diff((array)$obj1, (array)$obj2));

/* Output:
    Array
    (
        [prop] => Array
            (
                [1] => 2
            )
    )
*/

My solution will recursively diff a stdClass and all it nested arrays and stdClass objects. It is meant to be used for comparison of rest api responses.

function objDiff($obj1, $obj2):array { 
    $a1 = (array)$obj1;
    $a2 = (array)$obj2;
    return arrDiff($a1, $a2);
}

function arrDiff(array $a1, array $a2):array {
    $r = array();
    foreach ($a1 as $k => $v) {
        if (array_key_exists($k, $a2)) { 
            if ($v instanceof stdClass) { 
                $rad = objDiff($v, $a2[$k]); 
                if (count($rad)) { $r[$k] = $rad; } 
            }else if (is_array($v)){
                $rad = arrDiff($v, $a2[$k]);  
                if (count($rad)) { $r[$k] = $rad; } 
            // required to avoid rounding errors due to the 
            // conversion from string representation to double
            } else if (is_double($v)){ 
                if (abs($v - $a2[$k]) > 0.000000000001) { 
                    $r[$k] = array($v, $a2[$k]); 
                }
            } else { 
                if ($v != $a2[$k]) { 
                    $r[$k] = array($v, $a2[$k]); 
                }
            }
        } else { 
            $r[$k] = array($v, null); 
        } 
    } 
    return $r;     
} 

Here is a comparison function that I built using the pattern:

function objEq(stdClass $obj1, stdClass $obj2):bool { 
    $a1 = (array)$obj1;
    $a2 = (array)$obj2;
    return arrEq($a1, $a2);
}

function arrEq(array $a1, array $a2):bool {
    foreach ($a1 as $k => $v) {
        if (array_key_exists($k, $a2)) { 
            if ($v instanceof stdClass) { 
                $r = objEq($v, $a2[$k]); 
                if ($r === false) return false; 
            }else if (is_array($v)){
                $r = arrEq($v, $a2[$k]);  
                if ($r === false) return false; 
            } else if (is_double($v)){ 
            // required to avoid rounding errors due to the 
            // conversion from string representation to double
                if (abs($v - $a2[$k]) > 0.000000000001) { 
                    return false; 
                }
            } else { 
                if ($v != $a2[$k]) { 
                    return false; 
                }
            }
        } else { 
            return false; 
        } 
    } 
    return true;     
}

Usage:

$apiResponse = apiCall(GET, $objId);
$responseObj = json_decode($apiResponse);

// do stuff ...

if(!objEq($myObj, $responseObj) apiCall(PUT, $myObj, $objId);

Note that the apiCall function is just a mock to illustrate the concept. Also this solution is incomplete because it does not take into account any key->value pairs that are unique to obj2. In my use case this is not required and could be neglected.

NB: I borrowed heavily from Peter Hamiltons contribution. If you like what I did then please upvote his solution. Thanks!