Laravel Collection Public API: flatten

flatten

The flatten method will return a new Collection instance representing a flattened version of the original collection's items. The flatten method internally makes use of the Illuminate\Support\Arr::flatten($array) helper method. The flatten method will not preserve any keys from the original collection.

 1<?php
 2 
 3use Illuminate\Support\Collection;
 4 
 5// Create a new collection instance.
 6$collection = new Collection([
 7    'first',
 8    'second' => [
 9        'nested',
10        'array',
11        [
12            'deeply',
13            'nested'
14        ]
15    ],
16    'third' => 'some-value'
17]);
18 
19// Flatten the original collection.
20$flattenedCollection = $collection->flatten();

The $flattenedCollection variable will hold an instance of the Collection class and will have a value similar to the following output:

1object(Illuminate\Support\Collection)[134]
2  protected 'items' =>
3    array (size=6)
4      0 => string 'first' (length=5)
5      1 => string 'nested' (length=6)
6      2 => string 'array' (length=5)
7      3 => string 'deeply' (length=6)
8      4 => string 'nested' (length=6)
9      5 => string 'some-value' (length=10)

It is obvious in the above output that the flatten method does not preserve any of the original keys, and will even flatten deeply nested arrays.

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