parent :: method does not return connection

Question

parent :: method does not return connection

Navigation

#1 by (1 votes)

0

I have a Conn class that makes a connection to a SQL Server:

class Conn
{
    protected $con;
    protected $a = 'aaa';

    function __construct()
    {
        $this -> conecta();
    }

    private function conecta(){
        $serverName = "xxx.xxx.xxx.xxx";
        $connectionInfo = array( "Database"=>"XXX", "UID"=>"YYY", "PWD"=>"ZZZ", "CharacterSet" => "UTF-8");

        try {
            $conn = sqlsrv_connect($serverName, $connectionInfo);
        } catch (Exception $e) {
            echo "Erro na conexão com o BD.<br/>";
            die( print_r(sqlsrv_errors(), true));
        }

        if (!$conn){
            echo "Erro na conexão com o BD.<br/>";
            die( print_r(sqlsrv_errors(), true));
        } else {
            $this -> con = $conn;
            var_dump($this -> con);
        }
    }

    protected function getCon(){
        return $this -> con;
    }

}

And a BD class that extends the Conn class:

class BD extends Conn
{
    private $cnx;

    function __construct()
    {
        $this -> cnx = parent::getCon();
        var_dump($this -> cnx);
    }
}

When I create a BD object:

If in method getCon() I set return $this -> a; , it returns me: string(3) "aaa"

If in method getCon() I set return $this -> con; , it returns me: NULL where it should return resource(3) of type (SQL Server Connection)

I'd like to know what might be causing this or if I'm using it incorrectly.

php

asked by anonymous 20.07.2018 / 14:42

1 answer

javaScript function does not work when used ng-include angularJs mySQL - using SUM ()

score 1 · Accepted Answer

The $con object in Conn is only initialized when the Conn::conecta method is called, which in turn is called in the Conn constructor, but the Conn constructor is never called because the method was overridden in the child class BD .

If you need to override the constructor, you need to explicitly call the constructor of the parent class:

class BD
{
    public function __construct()
    {
        parent::__construct();
        // ...
    }
}

So, the constructor of the parent class will be executed, calling the conecta method and initializing the $con object. This way you can do:

class BD
{
    public function __construct()
    {
        parent::__construct();
        $this->cnx = $this->getCon();
    }
}

Note that it was invoked as $this->getCon() , since, as the Conn::getCon method is protected , it will inherit in BD as private , accessible within the class.