Question about passing pagination data when using pagy

[kinsomicrote]

Hello, thanks a lot for this gem! I'm confused about how to pass pagination data to my resource and expose it in the response. I tried this old issue as I'm also using pagy, but that didn't work.

include Pagy::Backend
def index
  items_per_page = 2
  applicants = Applicant.all
  @pagy, applicants = pagy(applicants, items: items_per_page)
  pagy = @pagy
  pagination_metadata_method = method(:pagy_metadata)
  with = proc do
    metadata :pagination do
      pagination_metadata_method.call(pagy, {url: true})
    end
  end
  render json: ::V1::ApplicantSerializer.new(applicants).serialize(meta: with), status: :ok
end

What was mentioned in the old issue is: render json: IssueResource.new(@issues).serialize(with: with). But with: returns an unknown keyword error.
My resource looks like this;

class ApplicantSerializer
    include Alba::Resource

    attributes .....
    attributes  ...., if: proc { !!params[:should_have_attachments] }

    attribute :dob do |resource|
      resource.dob.strftime('%d/%m/%Y')
    end
  end

Any helpful hints on what to do? Thanks.

[kinsomicrote]

Is there a unique or different way on how meta works? Asking cause I tried this;

::V1::ApplicantSerializer.new(aps, params: { pagination: { page: 2}}).serialize

And I have this in the serializer;

meta do
    { pagination: params[:pagination] }
  end

But that didn't work.

[kinsomicrote]

I "think" I figured it out - looks like meta was not working because I was not setting root_key.
My controller now looks like this;

...
pagy, applicants = pagy(applicants, items: items_per_page)
render json: ::V1::ApplicantSerializer.new(applicants, params: {pagination: pagy_metadata(pagy)}), status: :ok

Then in my serializer;

include Alba::Resource
root_key :applicant, :applicants
...
meta do
  if params[:pagination]
    {
      pagination: {
        next_page: params[:pagination][:next_url],
        prev_page: params[:pagination][:prev_url],
        prev: params[:pagination][:prev],
        next: params[:pagination][:next],
        from: params[:pagination][:from],
        to: params[:pagination][:to],
        count: params[:pagination][:count]
      }
    }
  else
    {}
  end
end

Let me know if there is a better way for this.

[okuramasafumi]

@kinsomicrote I think your solution is appropriate for now.
It might be a good idea to create a new API to configure pagination though. It might look like below:

class ApplicationSerializer
  include Alba::Resource

  paginate_with(key: :pagination) do |pagy|
    {
      next_page: pagy[:next_url],
      prev_page: pagy[:prev_url],
      prev: pagy[:prev],
      next: pagy[:next],
      from: pagy[:from],
      to: pagy[:to],
      count: pagy[:count]
    }
  end
end

::V1::ApplicantSerializer.new(applicants, {paginate_with: pagy_metadata(pagy)})

This could be more direct and clearer way to configure pagination.