Groups of states

[paulhennell]

Increasingly realising a lot of my projects would work far clearer with a state pattern, but hitting a repeated position where I want to filter on groups of states.

For an invoice style example you might want something like 'get all invoices that are payable' which might include DUE, OVERDUE and FAILED states. Obviously I can supply those to the whereState scope manually, but then adding a new invoice state (e.g. UPCOMING) means updating all queries to include the new class.

My first fix was just a quick array of classes available on the abstract state class - but that means the abstract state has to know what classes are payable, and it gives the abstract class a level of responsibility / knowledge of states.

My current system is instead to add a property to states like public static bool $payable = true; then add some helper functions to the abstract class:

//In abstract state class
public static bool $payable = false;

public static function Payable(): Collection
    {
        return static::isTrue('payable');
    }

    public static function isTrue(string $propertyName): Collection
    {
        return static::getStateMapping()->values()->filter(function ($class) use ($propertyName) {
            return $class::$$propertyName;
        })->values();
    }

Then the scope can be filtered with PaymentState::Payable() which reads pretty nicely, and new states simply decide to override the payable property or not.

I'm curious if this is
A) Missing a much simpler solution that I'll facepalm on when someone points it out (or I notice 3 mins after posting this ;))
B) An indication that $payable is it's own state or other kind of entity
C) Something that others also see a need for that could be assisted with something like getTrue on the state model / a trait etc

Interested to hear any thoughts!

[brendt]

It seems like a good solution if it fits your needs. Personally I'd code something like this in the model class and I wouldn't mind having to manually make changes if my state classes change. But if this works better for you, I'd say it's fine.