[11.x] Add whereEnum to route constraints

[osbre]

Extending #46703 with tests and explanation, as suggested in the comment.

Introducing whereEnum lets us limit the scope of a route parameter by providing an enum class, rather than listing out all of its values in whereIn. I'll give an example:

Before whereEnum one would have to do:

Route::get('/posts/{type}')->whereIn('type', [PostType::TypeA->value, PostType::TypeB->value, PostType::TypeC->value]);
Route::get('/posts/{post}');

And now it's just:

Route::get('/posts/{type}')->whereEnum('type', PostType::class);
Route::get('/posts/{post}');

Note

Both of these routes have to co-exist under the same /posts/ path, thus the need for limiting/constraints.

Btw, do not confuse route constraining with the ability to inject an enum-type parameter in a controller.

[osbre]

Alternatively, I can make a different PR to make whereIn support enum values, so that it could be used like this:

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

Let me know if this would be preferred instead of introducing whereEnum.

[joshmanders]

Alternatively, I can make a different PR to make whereIn support enum values, so that it could be used like this:

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

Let me know if this would be preferred instead of introducing whereEnum.

I like this route as it seems the cleanest.

[taylorotwell]

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