Challenge 3: Fix an N+1 Hiding Behind a Resource — Possible Solution
====================================================================

// The (unchanged) Resource — this class itself is NOT the problem

// app/Http/Resources/BookResource.php

class BookResource extends JsonResource
{
    public function toArray(Request $request): array
    {
        return [
            'id' => $this->id,
            'title' => $this->title,
            'author_name' => $this->author->name,   // direct relationship access
        ];
    }
}

// BEFORE — the controller feeds the Resource an un-eager-loaded query

// app/Http/Controllers/BookController.php

public function index()
{
    return BookResource::collection(Book::all());
    // For N books, $this->author->name inside toArray() triggers
    // 1 query per book — the classic N+1 pattern, just now happening
    // "inside" a Resource instead of a raw foreach loop.
}

// AFTER — fix the QUERY, not the Resource

public function index()
{
    return BookResource::collection(Book::with('author')->get());
    // BookResource's toArray() code is COMPLETELY UNCHANGED —
    // $this->author->name now reads from data already loaded in the
    // single eager-loading query, with zero extra queries per book.
}

WHY THE FIX BELONGS AT THE QUERY LEVEL
-------------------------------------------
BookResource::toArray() has no idea whether the underlying query eager
loaded author or not — it just accesses $this->author->name the same
way regardless. Eloquent's relationship-access magic transparently
handles BOTH cases (already loaded, or needs to lazy-load right now) with
identical syntax, which is exactly what makes this bug easy to introduce
and easy to miss: the Resource code looks correct in isolation, compiles
fine, and even WORKS correctly — it's just doing far more database work
than necessary.

Because the Resource class has no visibility into how the model
collection was originally queried, the only place the N+1 problem can
actually be fixed is at the query itself — adding with('author') before
the collection of Book models is ever handed to BookResource::collection().
This is the same lesson from Chapter 6 (the N+1 problem originates at
the query, not wherever the relationship happens to be accessed) applied
one layer further removed, now that a Resource class sits between the
query and the final response.

WHY THIS WORKS
--------------
- The fix requires touching exactly one line — the controller's query —
  and zero lines inside BookResource, demonstrating that "the Resource
  formats what's there" really does mean the fix is entirely a data-
  fetching concern, not a formatting concern.
- Verifying this fix in practice means checking the ACTUAL QUERY COUNT
  (e.g. via Laravel's query log, or a tool like Laravel Debugbar) before
  and after the change — confirming it drops from 1+N to a small, fixed
  number regardless of how many books exist, the same verification
  approach used for every other N+1 fix throughout this project.