Eager loading and method type injection

Question

I have a route that just shows some form:

Route::get('/form/{form}', 'FormController@show');

In the FormController, thanks to type injection I automagically convert form id (from {form}) to App\Form object and display it in the view:

public function show(Form $form){
    return view('form', compact('form'));
}

When I get a Form object through Eloquent query builder, I can eager load related elements/models like that:

$form = App\Form::where('id', '1497')->with('subform')->get()

Is there a way to automatically eager-autoload $form object with subform related object, or do I need to do it manually like that:

public function show($id){
    $form = App\Form::where('id', $id)->with('subform')->get();
    return view('form', compact('form'));
}

Answer 1

You can add relation by using load() method:

public function show(Form $form)
{
    return view('form', ['form' => $form->load('subform')]);
}

Answer 2

To automatically lazy load the subform when it is resolved in a route you can customize your route model binding. Define the custom resolution in the boot() method of App\Providers\RouteServiceProvider like:

public function boot()
{
    parent::boot();

    Route::bind('form', function ($id) {
        return App\Form::with('subform')->find($id);;
    });
}

This will resolve your route parameter {form} to the given form while automatically loading your subform.