JSON:API included relationship pagination

[Rasmus-Bertell]

I don't know if this is possible, but it is allowed as per the JSON:API spec¹ and would help with server loads. I tried to get it to work with Laravel 13 version, but couldn't figure out how to do it, if it is even possible.

<?php

namespace App\Http\Resources;

use Illuminate\Http\Request;
use Illuminate\Http\Resources\JsonApi\JsonApiResource;

class PostResource extends JsonApiResource
{
    public function toAttributes(Request $request): array
    {
        return [
            'title'        => $this->title,
            'slug'         => $this->slug,
            'body'         => $this->body,
            'published_at' => $this->published_at,
            'created_at'   => $this->created_at,
            'updated_at'   => $this->updated_at,
        ];
    }

    public function toRelationships(Request $request): array
    {
        return [
            'blog'     => BlogResource::class,
            'author'   => UserResource::class,
            // These should be paginated when included to avoid returning too much data
            'comments' => CommentResource::class,
            'tags'     => TagResource::class,
        ];
    }
}

Footnotes

1. A relationship object that represents a to-many relationship MAY also contain pagination links under the links member, as described below. Any pagination links in a relationship object MUST paginate the relationship data, not the related resources. ↩

[marius-ciclistu]

Hi. How would you go to page 2 of comments? Requesting same resource again would be a trafic waste.
How about when listing with comments?

I think that page 2 of comments should be retrieved from a different route:

/posts/{id}/comments?page=2

and to flag this in the initial response a bool flag could be returned: has_more_comments:true

Or
has_more_relations =>[comments => true]

This would mean retrieving n+1 comments, returning n of then and using the extra comment for the flag.

Eager loading comments on a list of posts would be affected by this, or maybe even blocked.

[Rasmus-Bertell]

The main thing is that the resource should be able to limit the number of results and have links where to fetch the next page, where those links point to is implementation details. The link would most probably point to the example you gave /posts/{id}/comments?page[number]=2&page[limit]=x, page limit would have to be the same that was passed in the initial request.

I don't see why a boolean flag would be needed since the response would have links for relationships present.

[marius-ciclistu]

For get /resource/{id} the links make sense. For list no.

[marius-ciclistu]

For my clients, I implemented a way to block requests asking for one to many relations on get by id or list, and I exposed the list related route. On this list the pagination is by default included anyway.

[marius-ciclistu]

To prevent this, you could fetch first the resoure with the one to many relation count and fetch the many relations via a second call.

[marius-ciclistu]

https://github.com/staudenmeir/eloquent-eager-limit this can be used for paginated eagerloading. It is included in laravel since v 11. It support offset and limit.

[colgecen]

yes it s possible; I had the same problem (on my e-commerce site)—the solution is simple
toRelationships() try something like this in the method:

public function toRelationships(Request $request): array
{
    return [
        'blog' => BlogResource::class,
        'author' => UserResource::class,
        'comments' => fn() => 
            CommentResource::collection(
                $this->whenLoaded('comments', fn() => 
                    $this->comments()->paginate(10)
                )
            ),
        'tags' => TagResource::class,
    ];
}

/*it also reduces server load*/

[marius-ciclistu]

This will retrieve all from db and paginate im php or it will paginate in db?

[colgecen]

it paginates in the database - not in php