Find the Page Number of a Model in Laravel's Pagination

We'll use the example of paginated comments. We want to be able to:

1. Jump to the page a specific comment sits on (e.g. using ?commentId=3489 in the URL's query string). This should redirect us to somewhere like /comments?page=65.
2. Redirect with a fragment (e.g. #comment-3489) to jump down to that comment.

This functionality is handy if you have a notification system within your application and need the ability to jump directly to a model, regardless of which page it's on.

The setup¶

Some basic setup will help you understand the rest of the article and how everything fits together. We'll also discuss finding the page where a reply to a comment sits.

The comment schema allows us to reference a parent_id for comment replies:

Schema::create('comments', function (Blueprint $table) {
    $table->id();
    $table->text('body');
    $table->foreignId('parent_id')->nullable()->constrained('comments');
    $table->timestamps();
});

And here's the comment model with the children relationship for replies:

class Comment extends Model
{
    public function children()
    {
        return $this->hasMany(Comment::class, 'parent_id', 'id')
            ->oldest();
    }
}

I've created a simple route to demonstrate everything, passing down paginated comments:

Route::get('/comments', function (Request $request) {
    $comments = Comment::with('children')->latest()->whereNull('parent_id');

    return view('comments', [
        'comments' => $comments->simplePaginate(10)
    ]);
})
    ->name('comments');

And here's what the view looks like:

<div>
    @foreach($comments as $comment)
        <x-comment-item :comment="$comment" />

        @foreach($comment->children as $child)
            <div style="margin-left: 20px;">
                <x-comment-item :comment="$child" />
            </div>
        @endforeach
    @endforeach

    <div>
        {{ $comments->links() }}
    </div>
</div>

This shows all top-level comments and replies (children) to comments. The comment-item Blade component is pretty simple:

<div id="comment-{{ $comment->id }}">
    <h3>#{{ $comment->id }}</h3>
    <p>{{ $comment->body }}</p>
</div>

Your setup may be different, but I hope that's given you a good idea of what we're working with.

Let's start to detect and redirect to the page a specific model is on!

Simple detection¶

We'll begin with simple, top-level detection and redirection and take it step-by-step.

First, we'll find the index of a commentId we pass into the URL. If this was the first comment in the list, we'd get 0 as the index. If it were 11th in the list (potentially on page 2 if we were splitting pages by 10), the index would be 10.

Route::get('/comments', function (Request $request) {
    $comments = Comment::with('children')->latest()->whereNull('parent_id');

    if ($commentId = (int) $request->get('commentId')) {
        $index = $comments->get()->search(function (Comment $comment) use ($commentId) {
            return $comment->id === $commentId;
        });

        dd($index); // the index position of the commentId
    }

    return view('comments', [
        'comments' => $comments->simplePaginate(10)
    ]);
})
    ->name('comments');

So, we have the index, how do we work out the page?

With knowing how many records we're displaying per page, the calculation is simple:

Route::get('/comments', function (Request $request) {
    $comments = Comment::with('children')->latest()->whereNull('parent_id');

    if ($commentId = (int) $request->get('commentId')) {
        $index = $comments->get()->search(function (Comment $comment) use ($commentId) {
            return $comment->id === $commentId;
        });

        $page = ceil(($index + 1) / 10);
    }

    return view('comments', [
        'comments' => $comments->simplePaginate(10)
    ]);
})
    ->name('comments');

That's it! $page will now contain the page the given comment lives on.

Lastly, just redirect the user to that page:

Route::get('/comments', function (Request $request) {
    $comments = Comment::with('children')->latest()->whereNull('parent_id');

    if ($commentId = (int) $request->get('commentId')) {
        $index = $comments->get()->search(function (Comment $comment) use ($commentId) {
            return $comment->id === $commentId;
        });

        $page = ceil(($index + 1) / 10);

        return redirect(
            Uri::route('comments')
                ->withQuery(['page' => $page])
                ->withFragment('comment-' . $commentId)
        );
    }

    return view('comments', [
        'comments' => $comments->simplePaginate(10)
    ]);
})
    ->name('comments');

Here, I use the Uri helper in Laravel to build up a Uri to redirect to. I also include the fragment (e.g. #comment-68), which will jump to that comment.

So now, a page like /comments?commentId=4569 will redirect to something like /comments?page=65#comment-4569.

If that's all you need, we're done! You can refactor/move this functionality away from your controller if required.

Let's now look at finding the page a nested comment (reply) sits on.

With relationships¶

To find a nested comment's page, we need to adjust the lookup of the $index we're looking for.

This logic will completely vary based on what you're working with, so adjust the code as needed.

Route::get('/comments', function (Request $request) {
    $comments = Comment::with('children')->latest()->whereNull('parent_id');

    if ($commentId = (int) $request->get('commentId')) {
        $index = $comments->get()->search(function (Comment $comment) use ($commentId) {
            return  $comment->id === $commentId ||
                    $comment->children()->oldest()->get()->contains('id', $commentId);
        });

        $page = ceil(($index + 1) / 10);

        return redirect(
            Uri::route('comments')
                ->withQuery(['page' => $page])
                ->withFragment('comment-' . $commentId)
        );
    }

    return view('comments', [
        'comments' => $comments->simplePaginate(10)
    ]);
})
    ->name('comments');

So, the only change required is looking inside the children of comments to see if the given comment exists as a reply.

If that's the case, we return the page for the top-level comment and redirect as normal, and we still jump to the nested comment with the fragment.

Conclusion¶

I've used this technique for finding and redirecting to the page a model sits on multiple times, and it works well.

This will slow down for very large data collections since we're using search on a Laravel collection and not checking at the database level. I wouldn't worry about this initially — just monitor it.