[Vuejs]-Laravel 9 + Vue3 + (vue-google-charts)

Your contacts_per_interests array should be look like this:

[
    ['interest_oid', 'total_cards'],
    [1, 2],
    [3, 1],
    [5, 2],
    [2, 1],
    [4, 1],
    [8, 1],
]

Adjust accordingly. Like that:

$json = '[
    {
        "interest_oid": 1,
        "total_cards": 2
    },
    {
        "interest_oid": 3,
        "total_cards": 1
    },
    {
        "interest_oid": 5,
        "total_cards": 2
    },
    {
        "interest_oid": 2,
        "total_cards": 1
    },
    {
        "interest_oid": 4,
        "total_cards": 1
    },
    {
        "interest_oid": 8,
        "total_cards": 1
    }
]';

$jsonArr = json_decode($json);

$array = [['interest_oid', 'total_cards']];
foreach ($jsonArr as $item) {
    array_push($array, [$item->interest_oid, $item->total_cards]);
}