Converting an array of strings to an array of integers in the controller

Hi,

I'm stuck on how to convert ['Category two', 'Category three'] to [2, 3] in the controller.

I have a User and Category models with a many-to-many relationship:

My categories table has 3 categories:

id: 1, name: 'Category one' id: 2, name: 'Category two' id: 3, name: 'Category three'

My category_user table looks like:

Schema::create('category_user', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->integer('user_id');
            $table->integer('category_id');
            $table->timestamps();
        });

In my blade template, I have a multi-select dropdown which the user can select categories from to which the user belongs. I then post the categories selected to my controller as an array of strings. I'm using Vuetify which uses strings rather than integer values in its multi-select component.

If the user selects categories 2 and 3, the array posted to the controller is:

['Category two', 'Category three']

I'd like to use sync() to update the categories associated with the user like so:

public function update_user_categories(Request $request)
    {
      $user = auth()->user();

      $user->categories()->sync($request->get('categoriesselected'));
      
      $user->save();

      return response()->json(null, 200);
    }

How do I convert $request->get('categoriesselected') into an array of integers that corresponds to category_id? I.e. convert

['Category two', 'Category three']

to

[ 2, 3 ]

Sorry if this is obvious...I'm still quite new to Laravel and PHP.