Need array of specificed key which exists within array of array

Question

So here is the data format in JSON. I need an array which contains all the array within "data_array".There can be multiple items in "main_array".Is there any way to do this without using any loop.Thank you

{
    "id" : "60561bbd1be6cb1972254ec4",
    "main_array": [
         {
            "data_array": [
                {
                    "_id": "6054d5c3dbd0af1cca71b857",
                    "qty" : 2000
                }
            ]
         },
         {
            "data_array": [
                {
                    "_id": "6054d5c3dbd0af1cca71b859",
                    "qty" : 78970
                },
                {
                    "_id": "6054d5c3dbd0af1cca71b860",
                    "qty" : 978
                }
            ]
        }
    ]
}

This is the expected array

[
         {
                    "_id": "6054d5c3dbd0af1cca71b857",
                    "qty" : 2000
         },
          {
             "id": "6054d5c3dbd0af1cca71b859",
             "qty" : 78970
          },
          {
             "_id": "6054d5c3dbd0af1cca71b860",
             "qty" : 978
          }

]

Currently I'm doing this

$expectedArray = [];
foreach($inputs['main_array'] as $mainArray){
    $expectedArray =array_merge($expectedArray,$mainArray['data_array']);
}

Answer 1

I got the answer to this question from here https://laracasts.com/discuss/channels/laravel/need-array-of-specificed-key-which-exists-within-array-of-array?page=1&replyId=771482

As I'm already getting converted data in array form.I removed json_decode().

$collect = collect($inputs['main_array']);
$data = $collect->pluck('data_array');
$flat = collect($data)->flatten(1);