How to use voter capabilities with workflow in symfony

You need to use a Voter for workflow entity for managing access policies when you use the Workflow component. Workflow component supports access policies with guard option, but the documentation won’t point out how to get the subject variable for a voter class.

I faced this situation when I was developing a feature for my last customer. I needed to dig into the workflow component`s code. I found out the class that getting guard config, parsing with expression language, and creating transaction blocker.

This class is evaluating expression with some variables.

$variables = [
            'token' => $token,
            'user' => $token->getUser(),
            'subject' => $event->getSubject(),
            'roles' => $roles,
            'role_names' => $roleNames,
            // needed for the is_granted expression function
            'auth_checker' => $this->authorizationChecker,
            // needed for the is_* expression function
            'trust_resolver' => $this->trustResolver,
            // needed for the is_valid expression function
            'validator' => $this->validator,
        ];

This is our solution, you can use these variables for writing your expression to workflow guard. I needed subject variable and I used to this in transaction configuration:

        to_rejected:
          guard: "is_granted('reject',subject)"
          from: draft
          to: rejected

Now I can use my voter class with full capabilities.