I am working on a blogging application in Laravel 8.

I run into a problem while trying to add a Next article and Previous article on the single article view.

In the ArticlesController controller I have this method to display a single article:

namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Models\User;
use App\Models\ArticleCategory;
use App\Models\Article;
use App\Models\Comment;

class ArticlesController extends FrontendController {

    // More code

    public function show($slug) {
        // Single article
        $article = Article::firstWhere('slug', $slug);
        $old_article = Article::firstWhere('id', '<', $article->id);
        $new_article = Article::firstWhere('id', '>', $article->id);
        $comments = Comment::where('article_id', $article->id)->orderBy('id', 'desc')->get();

        return view('themes/' . $this->theme_directory . '/templates/single', 
            array_merge($this->data, [
                'categories' => $this->article_categories,
                'article' => $article,
                'old_article' => $old_article,
                'new_article' => $new_article,
                'comments' => $comments,
                'tagline' => $article->title,
                ])
            );
    }
    
}

In the Blade view:

@if($old_article)
    <div >
      <a href="{{ url('/show/' . $old_article->slug) }}">
      <span>Older</span>
      {{ $old_article->title }} {{ $old_article->id }}
      </a>
    </div>
    @endif

    @if($new_article)
    <div >
      <a href="{{ url('/show/' . $new_article->slug) }}">
      <span>Newer</span>
      {{ $new_article->title }} {{ $new_article->id }}
      </a>
    </div>
@endif

The problem

For a reason I was unable to understand, the link to an older post does not work.

The line {{ $old_article->id }} always returns 1.

Questions

1. What causes this bug?
2. What is the easiest fix?

CodePudding user response：

If your $article has an ID of, let's say 10, then all Article records with an ID of 1 - 9 are "Older". You need to order your query so it gets the closest "Old" Article:

$article = Article::where('slug', $slug)->firstOrFail();

$oldArticle = Article::where('id', '<', $article->id)->orderBy('id', 'DESC')->first();

$newArticle = Article::where('id', '>', $article->id)->orderBy('id', 'ASC')->first();

Your "New" Article query was fine, default order is id, ASC, but for clarity, it doesn't hurt to make it consistent.