Sorting an StdClass Object Array by the values of another array

Question

I have an StdClass Array. Each object is ordered like this (there are about 50 objects in the array, but I thought I'd just put one to show the structure):

stdClass Object (
    [display_name] => Bob Simons
    [post_title] => Lesson 1
    [meta_value] => 100
    [comment_approved] => passed
    [c_num2] => 26
    [term_id] => 3
)

I have another array that looks like this:

Array ( 
    [0] => 3
    [1] => 4
    [2] => 5
    [3] => 16 
    [4] => 17 
    [5] => 18 
    [6] => 19 
    [7] => 20 
    [8] => 21 
)

The second array defines the sorting of the first one based on the [term_id] field. So essentially, everything with the [term_id] 3 should be at the top of the array, everything with the [term_id] 4 should be next, all based on that second array.

I am trying desperately to figure out how to do this, I've been looking at usort and the like but at a total loss.

I hope someone can help and will be really grateful.

Answer 1

Try this

$sortedArray = [];
foreach ($order as $termId) {
    foreach ($objects as $object) {
        if ($object->term_id == $termId) {
            $sortedArray[] = $object;
        }
    }
}

$objects holds your stdClass instances and $order your list with the ordered term ids.

In the case the term_id should always order in an ascending way, you can use usort :

usort($objects, function ($obj1, $obj2) {
    if ($obj1->term_id == $obj2->term_id) {
        return 0;
    }
    return ($obj1->term_id < $obj2->term_id) ? -1 : 1;
});