Question

Hopefully this isn’t a silly question and I’m just not overlooking something in Ruby/Rails state machines (AASM, Transitions, AlterEgo, etc).

From what I can tell, these state machine implementations operate on the preface that an event will get fired and the appropriate transition for that event will be triggered based on the old and new state. However, they don’t seem to work the other way; say a user wants to change state from ‘created’ to ‘assigned’ and have the correct transition occur, rather than firing the event that causes the current state to be transitioned to the new state.

Essentially, I want the user to be able to select a new state from a select box of available states and have the appropriate transition, guards, success callbacks, etc., executed.

Does anyone know if the existing state machine implementations support this?

Answer 1

You can accomplish what you are trying to do with my gem flojo.
Just name events after states and have those events trigger a transition from the wildcard state to the state selected in the drop down.

If you have a state “pending” in your drop down, you can configure a flojo event using the following snippet

event :pending do
  # :any is a wildcard state and is only valid as a begin state.
  transition :any, :pending
end

After your form is submitted, you would then have to prefix “pending” with “wf_”, convert it to a symbol and then send it to your object. It would be cleaner to just create a method in your class that does the prefixing and symbol conversion, and then delegates to send.

your_object.send :wf_pending

https://github.com/alternegro/flojo