use of binding in kernel laravel 8

Route Model Binding

When injecting a model ID to a route or controller action, you will often query the database to retrieve the model that corresponds to that ID. Laravel route model binding provides a convenient way to automatically inject the model instances directly into your routes. For example, instead of injecting a user’s ID, you can inject the entire User model instance that matches the given ID.

Implicit Binding

Laravel automatically resolves Eloquent models defined in routes or controller actions whose type-hinted variable names match a route segment name. For example:

use App\Models\User;
 
Route::get('/users/{user}', function (User $user) {
    return $user->email;
});

Since the $user variable is type-hinted as the App\Models\User Eloquent model and the variable name matches the {user} URI segment, Laravel will automatically inject the model instance that has an ID matching the corresponding value from the request URI. If a matching model instance is not found in the database, a 404 HTTP response will automatically be generated.

Of course, implicit binding is also possible when using controller methods. Again, note the {user} URI segment matches the $user variable in the controller which contains an App\Models\User type-hint:

use App\Http\Controllers\UserController;
use App\Models\User;
 
// Route definition...
Route::get('/users/{user}', [UserController::class, 'show']);
 
// Controller method definition...
public function show(User $user)
{
    return view('user.profile', ['user' => $user]);
}