Update serializers.md

[stratigos]

• Add note about ActionController::API and view_context set to nil, with respect to accessing helpers in a Serializer.

Purpose

Clarify a use case of scope that could present a problem when using a Rails 5 API controller. Refs #2144. If using the view_context for scope with an API controller, the view_context will always be nil, and helpers can not be accessed in a Serializer this way.

Changes

Added a note to the documentation, and demonstrated an example workaround.

Related GitHub issues

• Set serialization_scope and scope is nil in serializer #2144

Additional helpful information

• Related StackOverflow post on accessing a view helper inside a Presenter.

[bf4]

Isn't there anything else that might substitute for view_context? Maybe helpers? or just self?

[stratigos]

Long story short - I can remove the example I posted if it helps keep the documentation more clear and coherent.

When I was working on this for my own project, I found that Rails.application.helpers only included the helpers defined by the current application, (i.e., helpers you wrote), and does not include other view helpers, like NumberHelper or CsrfHelper etc.

I only proposed a generic solution to imply that "some class that has these modules included needs instantiated, somehow" and that view_context wont include them.

I understand if the example I provided is out of scope for the documentation, and also something you'd rather not officially represent. Would it be simpler if I just removed the example, and only left the note itself? I.e.,

Note that `view_context` is made available through `ActionController::Base`. The `view_context` will be `nil` when accessed from a controller that inherits from `ActionController::API`.

[bf4]

How about we edit anywhere on the page that says view_context (for subclasses of ActionController:Base), and adds another example or note that any controller reference which provides the desired scope is acceptable, for example :self may be useful for subclasses of ActionController::API which does not include ActionView::ViewContext ?

Thoughts?

[stratigos]

Im not sure if I follow the use of :self, as it too is always nil for:

class SomeApiController < ActionController::API
  serialization_scope :self
end

I think I can change the wording to match something similar to what you have above, though. I see what you mean generally - that just about any callable from the Controller can be passed into serialization_scope.

[bf4]

Thanks! 💯 for the PR. Question about whether the proposed solution is best. See there.

We should add a Rails5 test for this, too, I think

[bf4]

Awesome! Want to add yourself to the changelog?

[stratigos]

@bf4 Hows it look now?

[bf4]

Awesome! Want to add yourself to the changelog?

:) If not, I'll merge when it passes

[stratigos]

Sorry, I had updated the git log instead ;)

[stratigos]

Tysm! Happy to contribute something!