Getting query error in OOP php

Question

I'm just new using OOP php and I'm having a hard time to figure out how to query in database using class method. Here's my code and I've got an error which I dont know how to solve.

I declared the connection variable but I don't know why it's undefined

Notice: Undefined variable: connection

Fatal error: Call to a member function query() on a non-object in

db.php

class DbConnector {

   private $serverName;
   private $userName;
   private $password;
   private $dbName;
   private $connection;

   public function __construct(){
      $this->serverName = "localhost";
      $this->userName = "root";
      $this->password = "attl";
      $this->dbName = "oop";

      $this->connection = new mysqli($this->serverName, $this->userName, $this->password, $this->dbName);

      if ($this->connection->connect_error) {
          $this->connection = die("Connection failed: " . $this->connection->connect_error);
      } 
  }

  public function getConnection(){
      return $this->connection;
  }
}

index.php

include('../queries/db.php');

class Users{

  private $connection;

  public function __construct(){
      $con = new DbConnector();
      $connection = $con->getConnection();
  }
  public function getUsers(){
      $sql = $connection->query("SELECT * FROM login");

      while($getUsers = $sql->fetch_array()){
          echo $getUsers['username'];
      }
  }

}

$user = new Users();
return $user->getUsers();

It's very different on the link that tagged above @hanky panky — Genina Anne Gabuten, Jan 18 '17 at 10:33
Original question said `I'm getting error Notice: Undefined variable: connection in C:\xampp\htdocs\oop\views\index.php on line 13` so imho the duplicate flag is spot on it can help you with the solution quickly — Hanky Panky, Jan 18 '17 at 10:35
yes thanks for that, but it's very different since as looking for the link it's not a class OOP method. @HankyPanky — Genina Anne Gabuten, Jan 18 '17 at 10:40
Notice: Undefined variable: connection in C:\xampp\htdocs\oop\views\index.php on line 13 Fatal error: Call to a member function query() on a non-object in C:\xampp\htdocs\oop\views\index.php on line 13 . I don't know but the connection is declared . @MUNISHKUMAR — Genina Anne Gabuten, Jan 18 '17 at 10:41
kindly Reopen and remove the duplicate tagged @HankyPanky ? thanks — Genina Anne Gabuten, Jan 18 '17 at 10:48
@GeninaAnneGabuten Oh I see, glad to hear it. I was going to post my answer below if you still want me to and to mark it as solved. — Funk Forty Niner, Jan 18 '17 at 17:34
@GeninaAnneGabuten Actually, I did post my answer below just now, since I had it already written up beforehand and wrote it way before the other answer I saw now. — Funk Forty Niner, Jan 18 '17 at 17:37

score 3 · Accepted Answer · edited Jan 18 '17 at 17:42

Your problem is you're trying to access a locally scoped variable rather than a class property

public function getUsers(){
  $sql = $connection->query("SELECT * FROM login"); // HERE

  while($getUsers = $sql->fetch_array()){
      echo $getUsers['username'];
  }
}

this can't find a variable called $connection in that scope, you need to access the object property using $this.

class Users {

  private $connection;

  public function __construct()
  {
      $con = new DbConnector();
      // Assign this to object propety declared above 
      $this->connection = $con->getConnection();
  }

  public function getUsers()
  {
      // now access the object property set in constructor.
      $sql = $this->connection->query("SELECT * FROM login");

      while($getUsers = $sql->fetch_array()){
          echo $getUsers['username'];
      }
  }
}

*Cheers* Andrew. As I told the OP earlier; I didn't see your answer posted here where I asked her if the question was still open so I took the time to test it and figure out where she went wrong, and was in the process of typing it all up. Your answer explains it very well. — Funk Forty Niner, Jan 18 '17 at 17:46

score 0 · Answer 2 · answered Jan 18 '17 at 17:36

0

Since you're declaring the following as private:
private $connection;

and including it in your construct:

  public function __construct(){
      $con = new DbConnector();
      $connection = $con->getConnection();

You need to use $this for its property:

$this->connection = $con->getConnection();

Then changing:

$sql = $connection->query

to

$sql = $this->connection->query

in order to use the connection property.

Now, I have to admit that I am not an OOP expert and there may be another way to have solved this, yet this is what I took from it, which worked for me.

answered Jan 18 '17 at 17:36

Funk Forty Niner

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Thanks Free -ii- I just reprogram the code and run it. If u see my other Question AGAIN.. haha its different from here. But the other question is more on Controller which I don't know how it works. I just want to learn MVC slowly. – Genina Anne Gabuten Jan 18 '17 at 17:39
TBH, I had already written this up before seeing the other answer. I'm not kicking for rep here *lol* just saying. @GeninaAnneGabuten I'm just glad that you found your full solution. You're welcome *cheers* – Funk Forty Niner Jan 18 '17 at 17:40

Getting query error in OOP php

2 Answers2