Hey there! Let's work through this issue step by step.

Why the "Method paginate does not exist" error happens #

Your original myWishlist() method calls get() at the end, which immediately executes the query and returns a Collection instance. The paginate() method belongs to Laravel's QueryBuilder—collections don't have this method, hence the error.

Fix the myWishlist() method to support pagination #

Update your model method to return the query builder instead of executing the query right away. Remove the get() call:

// Wishlist model
public static function myWishlist()
{
    $userId = Auth::id();
    $bookIds = Wishlist::where('user_id', $userId)->pluck('book_id');
    
    // Return the query builder (no get() here!)
    return Book::whereIn('id', $bookIds);
}

Now this returns a query builder instance that you can chain paginate() onto in your controller.

Update your controller (small tweak included) #

Your controller code mostly works, but fix the pagination offset calculation to match your 20-items-per-page setting:

public function index(Request $request)
{
    $books = Wishlist::myWishlist()->paginate(20);
    
    return view('wishlistCRUD.index', compact('books'))
        ->with('i', ($request->input('page', 1) - 1) * 20); // Changed 5 to 20 for accurate numbering
}

Display the paginated books in your view #

In your wishlistCRUD.index blade view, loop through the $books collection to show each book, then add Laravel's built-in pagination links:

<!-- Render each book -->
@foreach($books as $book)
    <div class="book-card">
        <h4>{{ $book->title }}</h4>
        <p>By {{ $book->author }}</p>
        <!-- Add any other book details you need -->
    </div>
@endforeach

<!-- Render pagination buttons -->
<div class="pagination">
    {{ $books->links() }}
</div>

The links() method will generate fully functional pagination buttons (styled with Bootstrap by default, which you can customize if needed).

Bonus: Simplify with Eloquent Relationships #

For cleaner code, define a many-to-many relationship in your User model:

// User model
public function wishlistBooks()
{
    return $this->belongsToMany(Book::class, 'wishlists', 'user_id', 'book_id');
}

Then your controller can be shortened to:

public function index(Request $request)
{
    $books = auth()->user()->wishlistBooks()->paginate(20);
    
    return view('wishlistCRUD.index', compact('books'))
        ->with('i', ($request->input('page', 1) - 1) * 20);
}

This follows Laravel's best practices and eliminates the need for the static myWishlist() method entirely.

内容的提问来源于stack exchange，提问作者chhhar