Missing argument for closure with optional parameter

Question

I am in the process of working my way through a couple tutorials for Laravel 4 and I have run into a snag that I cannot figure out or comprehend as to why it is running incorrectly.

What I am trying to do compose a route that looks at the URL, and then works logically based on that. Here is my current code:

Route::get('/books/{genre?}', function($genre)  
{  
    if ($genre == null) return 'Books index.';  
    return "Books in the {$genre} category.";  
});

So if the URL is http://localhost/books, the page should return "Books index." If the URL reads http://localhost/books/mystery the page should return "Books in the mystery category."

However I am getting a 'Missing argument 1 for {closure}()' error. I have even referred to the Laravel documentation and they have their parameters formated exactly the same way. Any help would be appreciated.

Answer 1

If the genre is optional, you have to define a default value:

Route::get('/books/{genre?}', function($genre = "Scifi")  
{  
    if ($genre == null) return 'Books index.';  
    return "Books in the {$genre} category.";  
});

Answer 2

Genre is optional, you must define a default value to $genre. $genre=null so that it matches for "Book index" of your code.

Route::get('books/{genre?}', function($genre=null)
{
    if (is_null($genre)) 
        return "Books index";


return "Books in the {$genre} category";
});