Question

Let’s say I have following arrays:

$first = [
    ['id' => 5, 'name' => 'Education'],
    ['id' => 4, 'name' => 'Computers'],
    ['id' => 7, 'name' => 'Science'],
    ['id' => 1, 'name' => 'Sports'],
];

$second = [
    ['id' => 1, 'title' => 'Sport'],
    ['id' => 7, 'title' => 'Sci'],
    ['id' => 4, 'title' => 'Comp'],
    ['id' => 5, 'title' => 'Edu'],
];

And desired output is:

[
    ['id' => 5, 'name' => 'Education', 'title' => 'Edu'],
    ['id' => 4, 'name' => 'Computers', 'title' => 'Comp'],
    ['id' => 7, 'name' => 'Science', 'title' => 'Sci'],
    ['id' => 1, 'name' => 'Sports', 'title' => 'Sport'],
]

I have managed to merge these arrays with simply:

foreach ($first as $key => $value) {
    $result[$key] = array_merge($first[$key], $second[$key]);
}

But the output is combined by first level index instead of their id value:

Array
    (
        [0] => Array
            (
                [id] => 5
                [name] => Education
                [title] => Sport
            )

        [1] => Array
            (
                [id] => 4
                [name] => Computers
                [title] => Sci
            )

        [3] => Array
            (
                [id] => 7
                [name] => Science
                [title] => Comp

        [4] => Array
            (
                [id] => 1
                [name] => Sports
                [title] => Edu
            )
    )

I would like to append the title values from the second array to the first array where there is a matching id value and maintain the sorting of the first array.

How can I achieve this?

Answer 1

You can just do a nested loop and check if the id values match, then add title to $first (or name to $second)

foreach($first as $key => $value){
    foreach($second as $value2){
        if($value['id'] === $value2['id']){
            $first[$key]['title'] = $value2['title'];
        }               
    }
}