Global hooks for includes

[sean-wedig]

Lovely gem you have here - thanks for the work and support!

We're wondering if there's a means to hook into every association/include configuration across the app; we poked through the issues and PRs, and a bit through the code, and didn't see anything like that.

Some more context:

We're using the serializers for a variety of ActiveNode models, and we're in-process on adding an authorization layer. We do that by scoping requests for the models with an accessible_to(current_user) filter, e.g.,

class SomeModel 
  scope :accessible_to, lambda { |current_user|
    # ... whatever logic needed scope the query to what the user can see ...
  }
end

For direct access to these models, the serializers are just fine - we scope it before we call Serializer.serialize. However, this doesn't work when handling included associations, but we still need to restrict the queries.

We know we can use context to pass in the current_user from our controllers, and a serializer like the below in order scope the request to authorized models...

class SomeModelSerializer
  include JSONAPI::Serializer
 
  has_many :other_models do
    object.other_models.accessible_to(context[:current_user])
  end
end

But, naturally, this is something that we'd like to scope for every has_many or has_one. Like suggested in #105, we could add a helper method that we reference for all of our has_many/one configurations, like

class SomeModelSerializer # updated to streamline
  include JSONAPI::Serializer

  has_many :other_models, &:scope_to_current_user
end

But even that requires calling it out over and over again in the serializers with every association... we'd like to avoid that: we want the "default" for serializers to be the secure approach of limited access by user.

We're wondering if it would make sense to add global hooks we could use for includes with cross-cutting concerns like this. Something like an on_include hook that would fire whenever an include is used, passing in the object being serialized, the association name, context, etc...

We're happy to do a PR for this if it makes sense to do so, but we wanted to vet the idea first. Does this make sense / would it be valuable? Are there already-existing mechanisms for something like this that we overlooked?

Thanks!