Getting Array Difference for Object Arrays Based on Property Column

In the realm of PHP programming, the array_diff and array_udiff functions provide means to determine the differences between two arrays. However, when dealing with arrays of objects, a customized approach is necessary.

An array of objects, such as the one shown:

array(4) {
    [0]=>
        object(stdClass)#32 (9) {
            ["id"]=>
            string(3) "205"
            ["day_id"]=>
            string(2) "12"
        }
}

poses a unique challenge, especially if one wishes to determine the difference based on a specific column's values, such as "id" in the example.

To address this, the array_udiff function comes to our aid. It takes a third parameter, which is a user-defined function responsible for comparing the objects. By crafting a suitable comparison function, we can instruct array_udiff to perform the desired operation.

Here's an example of how to achieve this:

function compare_objects($obj_a, $obj_b) {
  return $obj_a->id - $obj_b->id;
}

$diff = array_udiff($first_array, $second_array, 'compare_objects');

In PHP 5.3 , anonymous functions can be employed instead of declaring a separate function:

$diff = array_udiff($first_array, $second_array,
  function ($obj_a, $obj_b) {
    return $obj_a->id - $obj_b->id;
  }
);

With these techniques, you now possess the ability to effectively determine the difference between arrays of objects by comparing the values from any desired column or property.