如何在已查询的集合中计算组内elequont对象的数量？

Question

This is my current output

Collection {#794 ▼
  #items: array:8 [▼
    "IN" => Collection {#795 ▶}
    "NZ" => Collection {#787 ▶}
  ]}

I want the items to be hold the no of count for each codes like

"IN" => 4,
"NZ" => 3,

I know that I can directly write in a query like this

$query->groupBy('country_code')->orderBy('country_code', 'ASC');
    return $query->get([
        DB::raw('country_code as country_code'),
        DB::raw('COUNT(*) as "count"')
    ]);

But I want the output from a already queried collection to reduce multiple queries which is a collection.

Right now I am only able to group by on the collection like this

$collection->groupBy('country_code');

Answer 1

$b = $a->groupBy('country_code');

You've done most of the job by proper grouping the data based on the country_code. Now it's just to iterate through the collection with a foreach, key, value and use the collections's count() method to count the number of elements stored under a given country_code

foreach ($b as $countryCode => $items) {
    echo $items->count()."
";
}

Reproduce:

php artisan ti
Psy Shell v0.7.2 (PHP 7.0.8-0ubuntu0.16.04.3 — cli) by Justin Hileman
>>> $cities = collect([['country_code' => 'pl', 'name' => 'Warszawa'], ['country_code' => 'pl', 'name' => 'Wrocław'], ['country_code' => 'de', 'name' => 'Berlin']]);
=> Illuminate\Support\Collection {#846
     all: [
       [
         "country_code" => "pl",
         "name" => "Warszawa",
       ],
       [
         "country_code" => "pl",
         "name" => "Wrocław",
       ],
       [
         "country_code" => "de",
         "name" => "Berlin",
       ],
     ],
   }
>>> $grouped = $cities->groupBy('country_code');
=> Illuminate\Support\Collection {#836
     all: [
       "pl" => Illuminate\Support\Collection {#838
         all: [
           [
             "country_code" => "pl",
             "name" => "Warszawa",
           ],
           [
             "country_code" => "pl",
             "name" => "Wrocław",
           ],
         ],
       },
       "de" => Illuminate\Support\Collection {#837
         all: [
           [
             "country_code" => "de",
             "name" => "Berlin",
           ],
         ],
       },
     ],
   }
>>> foreach ($grouped as $cCode => $cities) {
... echo $cCode . ' has '.$cities->count()."
";
... }
pl has 2
de has 1