Added when() method to InteractsWithInput trait

Author: pascalbaljet

src/Illuminate/Http/Concerns/InteractsWithInput.php

@@ -430,4 +430,20 @@ protected function retrieveItem($source, $key, $default)
 
         return $this->$source->get($key, $default);
     }
+
+    /**
+     * Apply the callback if the request contains a given input item key.
+     *
+     * @param  string  $key
+     * @param  callable|null  $callback
+     * @return $this
+     */
+    public function when($key, callable $callback)
+    {
+        if ($this->has($key)) {
+            $callback(data_get($this->all(), $key));
+        }
+
+        return $this;
+    }
 }

tests/Http/HttpRequestTest.php

@@ -300,6 +300,37 @@ public function testHasMethod()
         $this->assertTrue($request->has('foo.baz'));
     }
 
+    public function testWhenMethod()
+    {
+        $request = Request::create('/', 'GET', ['name' => 'Taylor', 'age' => '', 'city' => null]);
+
+        $name = null;
+        $age  = null;
+        $city = '';
+        $foo  = null;
+
+        $request->when('name', function ($value) use (&$name) {
+            $name = $value;
+        });
+
+        $request->when('age', function ($value) use (&$age) {
+            $age = $value;
+        });
+
+        $request->when('city', function ($value) use (&$city) {
+            $city = $value;
+        });
+
+        $request->when('foo', function () use (&$foo) {
+            $foo = 'test';
+        });
+
+        $this->assertSame('Taylor', $name);
+        $this->assertSame('', $age);
+        $this->assertNull($city);
+        $this->assertNull($foo);
+    }
+
     public function testMissingMethod()
     {
         $request = Request::create('/', 'GET', ['name' => 'Taylor', 'age' => '', 'city' => null]);