Add before_validation hooks to resources

[A-Boudi]

Solves #122

This adds a before_validation hook to be fired just before the before_commit hook.

[richmolj]

Thanks @A-Boudi - I want to take a closer look soon, but just glancing looks like a great PR. Just want you to know it's on my radar 👍

[richmolj]

You did a great job with the general setup, but I think this is the issue that would hold up the PR. We wanted something to fire before validation. As you can see and line 126 of resource_proxy.rb, this is happening after validation. IOW, we want to_not receive - and probably a Rails integration spec that addresses the original issue.

I don't think you're too far off though! Hope we get this in 👏 !

[A-Boudi]

Hi, @richmolj, I'm not sure if I did understand the issue correctly.

Here is what I originally understood:
During the persistance of a resource, graphiti works like this:

• Process resource's parents (mainly belongs_to relationships)
• Persist the resource with the foreing keys retrieved above
• Process resource's children (has_many and many_to_many relationships). Persist the children using the resource key.

If a resource has validation on its children, it can't be saved because the children are not accessible when the resource is being saved.

To fix this issue, the validation on children are scoped via a :whatever context. And a second round of validation is done using :whatever after that all the resource's parents and children are persisted and accessible.

Now, if we want something to fire before validation. Would this mean that this new callback should be fired before before_save callback?

[A-Boudi]

Hi @richmolj, what do you think?

[richmolj]

@A-Boudi thanks for the reminder and sorry for the delay. I think you have correct understanding of the issue, but the word validation is tripping things up. Graphiti "validation" is actually just checking model, instances for #errors - we expect the actual validation to be done with ActiveModel and performed during save.

So, this is maybe this is better named as before_validation_processing or after_graph_persisted or something like that.

Still, it should fire before Graphiti::Util::ValidationResponse code fires. Otherwise we'd be performing the validation, but nothing would happen in response (no rolling back the transaction or rendering errors correctly).

[A-Boudi]

Hi @richmolj,

Like asked, I moved this hook to fire before graphiti validation. I also changed the name to after_graph_persist.

For the tests, I have kept the test introduced in the first commit. And I added new integration tests that addresses the original issue.

[richmolj]

Really, REALLY great job @A-Boudi 💯 🥇 ! Thanks so much for sticking with it - I really appreciate the integration tests in particular ❤️ If you could please add an entry to the CHANGELOG, I'd be happy to merge!

[A-Boudi]

@richmolj CHANGELOG updated!