Laravel 5 Collections: Transforming Collection Elements With map

By John Koster April 22, 2018

The map method applies a given $callback to each item in the collection. The $callback can modify the item which will be added to a new collection. The map method does not modify the original collection, but returns a new collection instance with all the changes. The provided $callback should accept the $item and the items $key as its only arguments.

#Signature

1public function map(
2    callable $callback
3);

#Example Use

The following code example will transform the case of each string in the collection and return a new collection instance:

 1use Illuminate\Support\Collection;
 2
 3// Create a new collection instance.
 4$collection = new Collection([
 5    'first', 'second', 'third'
 6]);
 7
 8// Create a new collection where all the strings
 9// in the original collection have had their case
10// changed to upper-case.
11$newCollection = $collection->map(function($item, $key) {
12    return strtoupper($item);
13});

The $newCollection variable will be an instance of the Collection class and contain a value similar to following output:

1object(Illuminate\Support\Collection)
2  protected 'items' => 
3    array
4      0 => string 'FIRST'
5      1 => string 'SECOND'
6      2 => string 'THIRD'

The original $collection collection will remain unchanged.

#Using `map` with Higher Order Messages

In the section on the reject method we created a Product class to hold information about a product, and whether or not the product is on sale. Let's expand the Product class to implement the "Illuminate\Contracts\Arrayable" interface:

app/Product.php:

 1<?php
 2
 3use \Illuminate\Contracts\Support\Arrayable;
 4
 5class Product implements
 6{
 7    public $name = '';
 8    public $price = 0.0;
 9    public $onSale = false;
10
11    /**
12     * Determines if the product is on sale.
13     *
14     * @return bool
15     */
16    public function isOnSale() {
17        return $this->onSale === true;
18    }
19
20    /**
21     * Determines if the product is not on sale.
22     *
23     * @return bool
24     */
25    public function isNotOnSale() {
26        return !$this->isOnSale();
27    }
28
29    /**
30     * Converts the product to array.
31     *
32     * @return array
33     */
34    public function toArray()
35    {
36        return [
37            'name'  => $this->name,
38            'price'  => $this->price,
39            'onsale' => intval($this->onSale)
40        ];
41    }
42
43
44}

With the modified Product class, we can now use higher order messaging with Laravel collections like so:

 1$products = collect([
 2    [
 3    'name'   => 'Office Chair',
 4    'price'  => 399.99,
 5    'onSale' => false
 6    ],
 7    [
 8        'name'   => 'Desk',
 9        'price'  => 199.34,
10        'onSale' => true
11    ]
12])->transform(function ($item) {
13    $product = new Product;
14    $product->name = $item['name'];
15    $product->price = $item['price'];
16    $product->onSale = $item['onSale'];
17
18    return $product;
19})->map->toArray();

After the above code has executed, the $products array would contain the array representation of each of products.

∎

#Signature

#Example Use

#Using map with Higher Order Messages

#Using `map` with Higher Order Messages