Uncaught Error: Cannot call abstract method (PHP Fatal error)

Question

I am extending a abstract class that has two abstract methods. When I try to instantiate the the child class, I get following error,

 PHP Fatal error:  Uncaught Error: Cannot call abstract method GetAnswer::GetAnswer()

When I comment out the GetAnswer() in both parent and child things work fine.

PHP version: 7.0.2 in XAMPP, running on Wondows 8.1.

Parent class file app-getAnswer-base.php is as follows

<?php
abstract class GetAnswer{
    abstract public function GetAnswer($Username, $QuestionnaireID, $QuestionID);
    abstract public function GetAnswers($Username, $QuestionnaireID);
}

Child class file app-getAnswer-db-direct.php is as follows

<?php
require_once 'config-db-login.php';
require_once 'app-getAnswer-base.php';

class GetAnswer_SQLSelect extends GetAnswer {

    public function GetAnswer($Username, $QuestionnaireID, $QuestionID){
        return null;
    }    

    public function GetAnswers($Username, $QuestionnaireID){
        $connection = new mysqli(dbLogin::$db_hostname, dbLogin::$db_username, dbLogin::$db_password, dbLogin::$db_database);

        if ($connection->connect_error) die($connection->connect_error);

        $query = "SELECT `QuestionID`, `Answer` FROM `answerstore`.`answers` AS a JOIN  `answerstore`.`participants` AS b ON a.`ParticipantID` = b.`ParticipantID` WHERE a.`QuestionnaireID` = '$QuestionnaireID' AND b.`Username`='$Username'";

        $result = $connection->query($query);
        $connection->close();

        return $result;    
    }
}

Show the code where you make the call that throws the error. — Tschallacka
– Tschallacka, Commented Jul 6, 2016 at 11:35
@MichaelDibbets, is is $getAnswers = new GetAnswer_SQLSelect(); — Gamaka
– Gamaka, Commented Jul 6, 2016 at 11:37

Muhammad Sumon Molla Selim · Accepted Answer · 2016-07-06 11:32:15Z

3

I think when you are trying to instantiate the Child class it's calling the GetAnswer() method from the Parent class (GetAnswer) as it's working like a constructor.

Try changing the method name to something else.

answered Jul 6, 2016 at 11:32

Muhammad Sumon Molla Selim

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Comments

dios231 · Accepted Answer · 2016-07-06 11:38:12Z

-1

You have to instantiate the concrete class 'GetAnswer_SQLSelect' and then call the method 'GetAnswer'.

$GetAnswer_SQLSelect = new GetAnswer_SQLSelect(); //create new instance.
$GetAnswer_SQLSelect->GetAnswer($param1, $param2, $param3); //invoke method.

answered Jul 6, 2016 at 11:38

dios231

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1 Comment

dios231 Over a year ago

Then the possible issue is the one you referenced at your reply.

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