PHP - 将数据添加到嵌套数组特定索引的正确方法

What would be the proper / practical way to add information into nested array?

I have a problem pushing a data to specific index of array. I have foreach loop for my JSON file that I'm reading with PHP.

$array[] = array();
foreach($json["data"] as $inx => $key) {

        $field1 = $json["data"][$inx]["field1"];
        $field2 = $json["data"][$inx]["field2"];

        array_push($array[$field], $field2);
}

Data should look similar:

18732($field1) {
    123($field2),
    1234($field2),
    12345($field2),
    0983($field2),
    239823($field2),
    238742($field2)
}

How do I merge duplicate $field1's data to array which is "named" as $field1?

The error message is:

Warning: array_push() expects parameter 1 to be array, null given in D:\Installed\Xampp\htdocs\includes\core.php on line 71

Your code looks almost right, but you have:

1. A syntax error: $array[]= array();,
2. A typo:$field vs $field1
3. And the $array[$field1] is not defined when it is first accessed.

Corrected code:

$array = array();
foreach($json["data"] as $inx => $key) {

        $field1 = $json["data"][$inx]["field1"];
        $field2 = $json["data"][$inx]["field2"];

        if (!isset($array[$field1]))
            $array[$field1] = array();

        array_push($array[$field1], $field2);
}