PHP call to static function fails

Question

All,

I'm getting an error with the code below. Here is the error message I get:
Notice: Undefined variable: userDAO in C:\wamp\www\Projetv0.2\Model_User.php on line 15
and then
Fatal error: Call to a member function checkRecordExists() on a non-object in C:\wamp\www\Projetv0.2\Model_User.php on line 15

The relevant code is below. What I try to do with the code is have a unique class (DAO_DBrecord) to access several tables in a db. In the case below, I want to access my users table. To do that I have created a specific static function createUserDAO inside the DAO_DBrecord class that calls the constructor with the right table name, users. However, it doesn't work, and I can't figure why.

Model_User.php:

<?php
    require_once('Class_DB.php');
    require_once('DAO_DBrecord.php');

    class Model_user{ // Represents a connection to the users table in the DB
        private $db;
        private $userDAO;

        function __construct($db){
            $this->db=$db;
            $userDAO=DAO_DBrecord::createUserDAO($this->db);//  static function - calls constructor w/ 'user' table name parameter
            $this->userDAO=$userDAO;
        }
        function userInfoExists($userInfo, $colName){
            return $userDAO->checkRecordExists($userInfo, $colName);
        }
//Other stuff
    }
?>

DAO_DBrecord.php:

<?php
    require_once('Class_DB.php');

    class DAO_DBrecord {
        private $db;
        private $table;

        private function __construct($db,$table){
            $this->db=$db;
            $this->table=$table;
        }

        public static function createUserDAO($db) {
            return new DAO_DBrecord($db, 'users');
        }
//Other stuff
    }
?>

Thank you all for your help!

JDelage

cHao · Accepted Answer · 2012-01-21 21:20:42Z

2

That's not a problem with the static function. The problem is that PHP doesn't have an implicit $this. When you're referring to the member variable within the class (as you are in userInfoExists), you have to say $this->userDAO rather than just $userDAO.

Of course, all this assumes that the DAO_DBrecord class has or inherits a checkRecordExists function. If it doesn't, you're going to have other problems.

edited Jan 21, 2012 at 21:20

answered Jan 21, 2012 at 21:14

cHao

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1 Comment

JDelage Over a year ago

Doh... Thank you. It's always the dumbest mistakes that get me.

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