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Collections

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Use groupBy on Collections with Custom Callback Function

If you want to group result by some condition which isn’t a direct column in your database, you can do that by providing a closure function.

For example, if you want to group users by day of registration, here’s the code:

$users = User::all()->groupBy(function($item) {
    return $item->created_at->format('Y-m-d');
});

⚠️ Notice: it is done on a Collection class, so performed AFTER the results are fetched from the database.

Multiple Collection Methods in a Row

If you query all results with ->all() or ->get(), you may then perform various Collection operations on the same result, it won’t query database every time.

$users = User::all();
echo 'Max ID: ' . $users->max('id');
echo 'Average age: ' . $users->avg('age');
echo 'Total budget: ' . $users->sum('budget');

Calculate Sum with Pagination

How to calculate the sum of all records when you have only the PAGINATED collection? Do the calculation BEFORE the pagination, but from the same query.

// How to get sum of post_views with pagination?
$posts = Post::paginate(10);
// This will be only for page 1, not ALL posts
$sum = $posts->sum('post_views');

// Do this with Query Builder
$query = Post::query();
// Calculate sum
$sum = $query->sum('post_views');
// And then do the pagination from the same query
$posts = $query->paginate(10);

Serial no in foreach loop with pagination

We can use foreach collection items index as serial no (SL) in pagination.

   ...
   <th>Serial</th>
    ...
    @foreach ($products as $product)
    <tr>
        <td>{{ $loop->index + $product->firstItem() }}</td>
        ...
    @endforeach

it will solve the issue of next pages(?page=2&...) index count from continue.

Higher order collection methods

Collections have higher order methods, this are methods that can be chained , like groupBy() , map() ... Giving you a fluid syntax. This example calculates the price per group of products on an offer.

$offer = [
        'name'  => 'offer1',
        'lines' => [
            ['group' => 1, 'price' => 10],
            ['group' => 1, 'price' => 20],
            ['group' => 2, 'price' => 30],
            ['group' => 2, 'price' => 40],
            ['group' => 3, 'price' => 50],
            ['group' => 3, 'price' => 60]
        ]
];

$totalPerGroup = collect($offer['lines'])->groupBy('group')->map(fn($group) => $group->sum('price'));

Higher order collection message

Collections also provide support for "higher order messages", which are short-cuts for performing common actions on collections. This example calculates the price per group of products on an offer.

$offer = [
        'name'  => 'offer1',
        'lines' => [
            ['group' => 1, 'price' => 10],
            ['group' => 1, 'price' => 20],
            ['group' => 2, 'price' => 30],
            ['group' => 2, 'price' => 40],
            ['group' => 3, 'price' => 50],
            ['group' => 3, 'price' => 60]
        ]
];

$totalPerGroup = collect($offer['lines'])->groupBy->group->map->sum('price');

Get an existing key or insert a value if it doesn't exist and return the value

In Laravel 8.81 getOrPut method to Collections that simplifies the use-case where you want to either get an existing key or insert a value if it doesn't exist and return the value.

$key = 'name';
// Still valid
if ($this->collection->has($key) === false) {
    $this->collection->put($key, ...);
}

return $this->collection->get($key);

// Using the `getOrPut()` method with closure
return $this->collection->getOrPut($key, fn() => ...);

// Or pass a fixed value
return $this->collection->getOrPut($key, $value='teacoders');

Tip given by @Teacoders

Static times method

The static times method creates a new collection by invoking the given closure a specified number of times.

Collection::times(7, function ($number) {
    return now()->addDays($number)->format('d-m-Y');
});
// Output: [01-04-2022, 02-04-2022, ..., 07-04-2022]

Tip given by @Teacoders