如何比较数组内的对象值？

Question

I have an array containing several objects.

$products = [
            {"id":"1","random":"sadasd","mergethis":"Ding"},
            {"id":"2","random":"assdfsadf","mergethis":"Ding"},
            {"id":"2","random":"assdfsadf","mergethis":"Flop"},
            {"id":"2","random":"assdfsadf","mergethis":"Bips"},
            {"id":"3","random":"sdfss","mergethis":"Flung"},
            {"id":"3","random":"sdfss","mergethis":"Rorg"},
            {"id":"4","random":"asdasdddaf","mergethis":"Shwung"}
            ]

I'm trying to iterate trough this array and when the id is allready present in the array, I want to add the value of mergethis with the first hit that has the same id, seperated with a comma, and then unset the object from the array.

So my expected outcome would become:

[
{"id":"1","random":"sadasd","mergethis":"Ding"},
{"id":"2","random":"assdfsadf","mergethis":"Ding,Flop,Bips"},
{"id":"3","random":"sdfss","mergethis":"Flung,Rorg"},
{"id":"4","random":"asdasdddaf","mergethis":"Shwung"}
]

I'm trying to iterate trough $products and compare the values but I'm stuck at comparing the value to a subvalue of the array in stead of to the entire array

foreach($products as $key => $value){
    if (in_array($value->id, $products)) {
        //Delete this item and add product_category comma sepereated to first item
        //unset($products[$key]);
    }
}

This obviously doesn't work because it compares the item to the entire array in stead of to the sub value id of the array item.

How do I go about getting my expected outcome?

Do I need to create a new array filled with the keys and id values of each array item and iterate trough that? Or is there an easier method to compare object values inside an array to each other?

Answer 1

Hint: Use associative array with id as key and the whole product as value:

$results = array();
foreach ($products as $prod){
    if (array_key_exists($prod['id'], $results)){
        $results[$prod['id']]['mergethis'] .= ',' . $prod['mergethis'];
    } else {
        $results[$prod['id']] = $prod;
    }
}