Implement pagination feature for related routes

[sangeethailango]

Problem:

The pagination feature is currently not functioning as expected for related routes in the ash_json_api gem. Specifically, when fetching related records for a resource, the records are returned without pagination, even though pagination is correctly implemented for the primary resource.

Example setup:

  use Ash.Resource,
    domain: Account.Domain,
    data_layer: AshPostgres.DataLayer,
    extensions: [AshJsonApi.Resource]

  ...
  
actions do
    read :read do  
      pagination countable: true, offset?: true, required?: true, default_limit: 10
    end
  end

  relationships do
    has_many :comments, Comment
  end
end

comment resource

  use Ash.Resource,
    domain: Account.Domain,
    data_layer: AshPostgres.DataLayer,
    extensions: [AshJsonApi.Resource]

  ...
  
  actions do
   read :read do  
      pagination countable: true, offset?: true, required?: true, default_limit: 10
   end
  end

  relationships do
    belongs_to, :article, Article
  end
end

Domain

defmodule Account.Domain do
  use Ash.Domain, extensions: [AshJsonApi.Domain]

  alias Accounts.Blog.{Article, Comment}
  
  json_api do
    routes do
      base_route "/articles", Article do
        get :read
        related :comments, :read
      end
    end
  end

When making a GET request to articles/:article_id/comments, the related comments are not paginated. However, pagination works correctly when fetching the articles directly from /articles.

Expected Behavior:

The pagination functionality should be applied to related routes just as it is for the primary resource. For instance, when accessing related comments through the endpoint articles/:article_id/comments, the response should include pagination controls and adhere to the pagination settings defined for the :read action on the Comment resource.

Proposed Solution:

• Implement pagination for related routes similar to how it is implemented for primary resources.
• I have already created an issue about this on elixir forum where @zachdaniel proposed a solution: https://elixirforum.com/t/pagination-is-not-working-for-related-resources/66057

[Dgoz101]

This looks interesting to me. Is this something that still needs done? I've read the solution that was proposed in the link.

[zachdaniel]

Good question, I'm not sure if it's been done here or not yet, but given that Ash core now supports paginating relationships it should actually be quite simple! I'd check the pagination guides in Ash core for more 😄

[zachdaniel]

(first confirm if we do/don't support it already, I'd have to double check)

[Dgoz101]

From what I see, it looks like this can still be added. I'll work on it.