Symfony2 Service Response - php

Question

i was trying to setup a general service which handles common function i use very often everywhere in my project. For example if a user wants to purchase something for virtual currency there would be a function which checks, if the user has enough virtual currency in his account.
If the user doesnt have enough virtual currency I want this function to make a JSOn Response, but of cource, only controllers are allowed to response. But this means i have to check in every action I use this function, whether the purchase is valid or not.
Here is the function call in my Controller:
$purchaes= $this->get('global_functions')->payVirtualCurrency($user_id, $currency_amount);
if($change instanceof JsonResponse){
return $change;
}
And the function:
public function payVirtualCurrency($user_id, $currency_amount){
$user = $this->dm->getRepository('LoginBundle:User')->findOneById($user_id);
if($user->getVirtualCurrency() < $currency_amount){
return new JsonResponse(array('error' => $this->trans->trans('Insufficient amount of virtual Currency')));
}
return true;
}
Is there a better way to do this? I really want to avoid doing the same thing in the controller over and over again.
Thanks in advance!

Answer 1

Two options come to my mind, both are quite elegant solutions but both require little work:
1. Create custom exception listener
Create custom exception, let's call it InsufficientMoneyException. Then, your sevice can be as it is, but instead of returning response it throws your custom exception (in case user does not have enough money). Then, you create custom exception listener which listenes to InsufficientMoneyException custom exception and returns your desired JsonResponse.
2. Create custom annotation
You can create custom annotation and flag a controller action with this annotation. It would look something like this
/**
* #MinimumMoneyRequired("50")
*/
public function buyAction()
{
(...)
}
This option is really nice and decoupled but it require quite a lot of configuration. This is nice blog post with detailed description how to create custom annotations