[11.x] Add support for enums in whereIn route constraints

[osbre]

Currently, passing an array of enum cases results in an exception:

Route::get('/posts/{type}')->whereIn('type', PostType::cases());

// Error: Object of class Illuminate\Tests\Routing\CategoryBackedEnum could not be converted to string

This change fixes it, allowing us to pass array of enums into whereIn.

Probably interchangeable with #51104

[taylorotwell]

Fine with merging this, but note you could just type hint the Enum in your route parameter and you wouldn't need this whereIn call at all. 😅

[vanodevium]

@taylorotwell

It's undocumented feature

[taylorotwell]

@vanodevium https://laravel.com/docs/11.x/routing#implicit-enum-binding ?

[osbre]

@taylorotwell Unfortunately, it's not the same in certain cases. Perhaps later I can send a test update to further demonstrate why.

[vanodevium]

@taylorotwell

I'm sorry that I'm just now writing my comment.

I will try to explain my vision of the problem to you as simply as possible.

Let's imagine that we have the following routing configuration:

Category enum is taken from the documentation, values: [fruits, people]

Route::get('/{category}', function (Category $category) {
    dd("This is case without unpacking enum values into RegEx");
});

Route::get('/news', function () {
    dd("This is NEWS page");
});

According to the documentation, for this configuration I will never get to the news page, because the request will always fall into the first route, but enum does not have a news value, so it will be raise 404. Everything is as written in the documentation, I completely understand.

Of course, I can push the news to the top and everything will work as it should.

But the question is: why such behavior?
It's simple: because enum is not unpacked into a regular expression at the matching step, so anything gets into the resolver and shows a 404.

Ok, how to fix it?. Very easy:

Route::get('/{category}', function (Category $category) {
    dd("This is case with unpacking enum values into RegEx");
})->whereIn('category', Category::cases());

Route::get('/news', function () {
    dd("This is NEWS page");
});

In this version, everything that is not suitable for the enum will not get into the first route.
And I'll be happy to see news page as I want.

---

So maybe ->whereEnum('name', Enum::class) helper with automatic unpacking into regex is no so bad idea?