从不同的控制器调用时，PHP / Laravel父类变量为null

Question

Parent Class:

<?php

namespace App\Services;

class RequestVariables {

    protected static $keys_tour;

    public static function init() {

    self::$keys_tour = array_flip(['tour_type', 'city_from']);

    }

}

Child Class:

<?php

namespace App\Services;

class PreviousVersions extends RequestVariables {

       public static function createVersion ($tour) {

            dd(parent::$keys_tour);

  }
}

When I call PreviousVersions::createVersion() from 1st controller:

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;    

use App\Services\PreviousVersions;

use App\Tour;

class Tours2Controller extends Controller

{

    public static function PreProcess($tour)

    { 

        PreviousVersions::createVersion($tour);
    }

}

it outputs what's expected:

array:2 [
  "tour_type" => 0
  "city_from" => 1 ]

but when I execute the same function in another controller:

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

use App\Tour;

use App\Services\PreviousVersions;


class BookingController extends Controller {

    public function booking($tour)

    {

      PreviousVersions::createVersion($tour);

    }

}

it outputs 'null'

I can't see what's different between my controllers causing different results when calling the same method. Can somebody tell me why it outputs 'null' in the 2nd case?

If you need more information, please ask.

Answer 1

The $keys_tour property is being set inside the init() method of the RequestVariables class.

You can solve it by calling RequestVariables::init() inside the createVersions() method:

public static function createVersion ($tour)
{
    RequestVariables::init();
}

Or using the parent keyword:

public static function createVersion ($tour)
{
    parent::init();
}