State machines [3d]
Requirements
Movies in MovieDB should have one of the following workflow states:
draft
pending
published
declined
A movie always begins as a draft
and then transitions through the states as it's getting reviewed. This could be a typical state flow for a movie:
stateDiagram-v2
[*] --> draft
draft --> pending
pending --> declined: Reason
declined --> pending
pending --> published
Change the visibility rules (Consul powers) so:
- All users can see published movies of other users.
- All users can see the movies they created themselves, regardless of their state.
- An admin can see movies from other users that are published, pending or declined.
We will now add some additional controls to transition a movie between states:
- When a user views one of her draft or declined movies, she sees a button Submit on the movie's show view. This changes the movie's state to
pending
. - When an admin opens a
pending
movie by any user, she sees two buttons Publish and Decline. - Before the admin may decline a movie, she is required to enter a declining reason. The declining reason should be entered in a form like the other forms in your app, with the same form round trip and controller handling. Consider whether you want to implement this inside an existing
:movies
resource or in a new one just for the declining form. - In addition, when an admin edits a movie by any user, she can choose any state from a select box, regardless of the movie's current state. Note that any transition constraints and callbacks will not be enforced when the
#state
is set directly. We only do this to allow admins to correct user errors.
Implementation
Make two implementations of the requirements above:
- Using only Ruby/Rails and no state machine gems
- Using a gem like rails_state_machine Show archive.org snapshot
Make sure that you have tests for all the changes you make.
Tip
factory_bot offers traits Show archive.org snapshot to define variants of a factory. Your default factory should create records in a state that is useful for the vast majority of tests.