Laravel collection macro (spatie#158)

* add laravel collection macro, docs, test

* cleanup test

* StyleCI fixes

README.md

@@ -51,6 +51,18 @@ There's also a very short syntax available to quickly transform data:
 fractal($books, new BookTransformer())->toArray();
 ```
 
+You can transform directly from a Laravel collection as well:
+
+```php
+collect($books)->transformWith(new BookTransformer());
+```
+
+Transforming right from a Laravel collection is particularly useful for Eloquent results:
+
+```php
+Users::all()->transformWith(new UserTransformer())->toArray();
+```
+
 Spatie is a webdesign agency based in Antwerp, Belgium. You'll find an overview of all
 our open source projects [on our website](https://spatie.be/opensource).
 
@@ -73,7 +85,7 @@ composer require spatie/laravel-fractal
 
 The package will automatically register itself.
 
-If you want to [change the default serializer](https://github.com/spatie/fractalistic#changing-the-default-serializer), 
+If you want to [change the default serializer](https://github.com/spatie/fractalistic#changing-the-default-serializer),
 the [default paginator](https://github.com/spatie/fractalistic#using-pagination),
 or the default fractal class `Spatie\Fractal\Fractal`
 you must publish the config file:
@@ -236,7 +248,7 @@ We publish all received postcards [on our company website](https://spatie.be/en/
 
 Spatie is a webdesign agency based in Antwerp, Belgium. You'll find an overview of all our open source projects [on our website](https://spatie.be/opensource).
 
-Does your business depend on our contributions? Reach out and support us on [Patreon](https://www.patreon.com/spatie). 
+Does your business depend on our contributions? Reach out and support us on [Patreon](https://www.patreon.com/spatie).
 All pledges will be dedicated to allocating workforce on maintenance and new awesome stuff.
 
 ## License

src/FractalServiceProvider.php

@@ -2,6 +2,7 @@
 
 namespace Spatie\Fractal;
 
+use Illuminate\Support\Collection;
 use Illuminate\Support\ServiceProvider;
 use Laravel\Lumen\Application as LumenApplication;
 use Spatie\Fractal\Console\Commands\TransformerMakeCommand;
@@ -21,6 +22,8 @@ public function boot()
                 TransformerMakeCommand::class,
             ]);
         }
+
+        $this->setupMacro();
     }
 
     /**
@@ -47,4 +50,14 @@ protected function setupConfig()
 
         $this->mergeConfigFrom($source, 'fractal');
     }
+
+    /**
+     * Add a 'transformWith' macro to Laravel's collection.
+     */
+    protected function setupMacro()
+    {
+        Collection::macro('transformWith', function ($transformer) {
+            return fractal($this, $transformer);
+        });
+    }
 }

tests/LaravelCollectionMacroTest.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Spatie\Fractal\Test;
+
+use Illuminate\Support\Collection;
+
+class LaravelCollectionMacroTest extends TestCase
+{
+    /** @test */
+    public function it_provides_laravel_colletion_macro()
+    {
+        $transformedData = Collection::make($this->testBooks)
+            ->transformWith(new TestTransformer())
+            ->toArray();
+
+        $expectedArray = ['data' => [
+            ['id' => 1, 'author' => 'Philip K Dick'],
+            ['id' => 2, 'author' => 'George R. R. Satan'],
+        ]];
+
+        $this->assertEquals($expectedArray, $transformedData);
+    }
+}