PHP - All Digits To Be As Pairs?

The client provides name/value pairs which are used to update something and I am currently using switch statements to direct the action based on the provided name, however, it is becoming increasingly more complicated.  Are there any standard approaches to doing so?  I am thinking of doing the following.  Any concerns?  Thanks

$c['fooService'] = function ($c) {
    return new Foo\FooService(
        new Foo\FooMapper(),
        new ApiConnector(),
        new Foo\FooNameValueUpdater(),
    );
};

$app->put('/foo/{id:[0-9]+}', function (Request $request, Response $response, $args) {
    return $this->fooResponder->update($response, $this->fooService->update($args['id'], $request->getParsedBody()));
});

Class FooService extends BarService
{
    public function __construct($mapper, $updater, $apiConnector) {
        $this->mapper = $mapper;
        $this->apiConnector = $apiConnector;
        $this->updater = $updater;
    }

    public function update($id, $params) {
        //$params=['name'=>'property1name', 'value'=>123]
        $this->updater->$params['name']($id, $params['value'], $this);
    }

    public function updateSomeStandardAction($id, $value, $propertyName) {
        //some code...
        $this->mapper->bla($id, $value, $propertyName);
    }

    public function updateSomeOtherStandardAction($id, $value, $propertyName) {
        //some code...
        $this->apiConnector->bla($id, $value, $propertyName);
    }
}

Class FooNameValueUpdater extends BarNameValueUpdater
{
    public function property1name($id, $value, $service) {
        $this->updateSomeStandardAction($id, $value, $service, 'property1name');
    }
    public function property2name($id, $value, $service) {
        $this->updateSomeStandardAction($id, $value, $service, 'property2name');
    }
    public function property3name($id, $value, $service) {
        $this->updateSomeStandardAction($id, $value, $service, 'property3name');
    }
    public function property4name($id, $value, $service) {
        $this->updateSomeStandardAction($id, $value, $service, 'property4name');
    }

    protected function updateSomeStandardAction($id, $value, $service, $propertyName) {
        //some code...
        $service->updateSomeStandardAction($id, $value, $propertyName);
    }

    protected function updateSomeOtherStandardAction($id, $value, $service, $propertyName) {
        //some code...
        $service->updateSomeOtherStandardAction($id, $value, $propertyName);
    }
}

I implemented an endpoint which receives name/value pairs:

PUT someresource/123 {"name": "description", "value": "Some new description"}

I think I made a mistake, and should have implemented it as:

PUT someresource/123 {"description": "Some new description"}

The reason I think so is updating multiple properties is only (easily) possible using the later:

PUT someresource/123 {"description": "Some new description", "otherProperty": "bla bla bla"}

Assuming I am not using some 3rd party client library which only works with name/value pairs, any compelling reason why one shouldn't default to the later approach with key/values?

This is the cart array:
$cart = array( "1" => "2", "3" => "4", "5" => "6");
var_dump($cart);
array(3) { [1]=> string(1) "2" [3]=> string(1) "4" [5]=> string(1) "6" }
This is the cart items array:
$cart_items = array();
$cart_items["id"] = $id;
$cart_items["quantity"] = $quantity;
var_dump($cart_items);
array(2) { ["id"]=> array(2) { [0]=> string(1) "1" [1]=> string(1) "1" } ["quantity"]=> array(2) { [0]=> string(1) "1" [1]=> string(1) "1" } }

I want the key to be "id" and the value to be "quantity" like it is for the cart array. How do I define my cart_items array using variables?