Uncaught error: call to a member function query() on null

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PHP

MVC

null

Was making a small shop app, and got this error. To me it looks strange, because the query function in php is in-built and in my case it should work properly. But it doesn't.

The error text.

Fatal error:  Uncaught Error: Call to a member function query() on null in C:\Program Files\Ampps\www\MCV for nordcurrent\app\models\model_product_list.php:45
Stack trace:
#0 C:\Program Files\Ampps\www\MCV for nordcurrent\index.php(5): Card->get_cards()
#1 {main}
  thrown in C:\Program Files\Ampps\www\MCV for nordcurrent\app\models\model_product_list.php on line 45

Code the is in question.

  1  <?php
  2  
  3  /* Card class - proccesses all the infromation displayed in the cards */
  4  
  5  class Card
  6  {
  7      private $Database;
  8      private $db_table = 'card_table';
  9  
 10      function __constructor()
 11      {
 12          global $Database;
 13          $this->Database = $Database;
 14      }
 15  
 16      //Setting / Getting cards from the database
 17  
 18      //Return and array with card information
 19      public function get_cards($id = NULL)
 20      {
 21          $data = array();
 22          if($id != null)
 23          {
 24              //get specific card
 25              if($stmt = $this->Database->prepare("SELECT id, name FROM " . 
 26              $this->db_table . " WHERE id = ?" ))
 27              {
 28                  $stmt->bind_param("i", $id);
 29                  $stmt->execute();
 30                  $stmt->store_result();
 31  
 32                  $stmt->bind_result($card_id, $card_name);
 33                  $stmt->fetch();
 34  
 35                  if($stmt->num_rows > 0)
 36                  {
 37                      $data = array('id' => $card_id, 'name' => $card_name);
 38                  }
 39                  $stmt->close();
 40              }
 41          }
 42          else
 43          {
 44              //get all cards
 45             (The 45th line where the error is coming from) 
 46             if($result = $this->Database->query("SELECT * FROM " . $this->db_table . "
 47              ORDER BY name"))
 48              {
 49                  if($result->num_rows > 0)
 50                  {
 51                      while($row = $result->fetch_array())
 52                      {
 53                          $data[] = array('id' => $row['id'], 'name' => $row['name']);
 54                      }
 55                  }
 56              }
 57          }
 58          return $data;
 59      }
 60  
 61  
 62  }

What I have tried:

This is the n'th time when I've use this same code snippet to generate a request to a database. But this is the first time I'm getting a null error.