laravel 缺少带有可选参数的闭包参数
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Missing argument for closure with optional parameter
提问by Triccum
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.
我正在学习 Laravel 4 的几个教程，但遇到了一个问题，我无法弄清楚或理解它为什么运行不正确。
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:
我正在尝试编写一个查看 URL 的路由，然后基于该 URL 进行逻辑工作。这是我当前的代码：
Route::get('/books/{genre?}', function($genre)
{
if ($genre == null) return 'Books index.';
return "Books in the {$genre} category.";
});
So if the URL is http://localhost/books, the page should return "Books index." If the URL reads http://localhost/books/mysterythe page should return "Books in the mystery category."
因此，如果 URL 是http://localhost/books，则页面应返回“图书索引”。如果 URL 读取http://localhost/books/mystery页面应返回“神秘类别的书籍”。
However I am getting a 'Missing argument 1 for {closure}()' error. I have even referred to the Laravel documentation and they have their parameters formated exactly the same way. Any help would be appreciated.
但是，我收到“{closure}() 缺少参数 1”错误。我什至参考了 Laravel 文档，它们的参数格式完全相同。任何帮助，将不胜感激。
回答by Fernando Montoya
If the genre is optional, you have to define a default value:
如果流派是可选的，则必须定义一个默认值：
Route::get('/books/{genre?}', function($genre = "Scifi")
{
if ($genre == null) return 'Books index.';
return "Books in the {$genre} category.";
});
回答by user3467678
Genre is optional, you must define a default value to $genre. $genre=nullso that it matches for "Book index"of your code.
流派是可选的，您必须将默认值定义为$genre。$genre=null以便它与您的代码的“书籍索引”相匹配。
Route::get('books/{genre?}', function($genre=null)
{
if (is_null($genre))
return "Books index";
return "Books in the {$genre} category";
});
