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PONot able to get a Database instance inside a Model class
 

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  1. PONot able to get a Database instance inside a Model class
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    <p>Does a class' __construct() method need to be public, in order to call a static method of this class inside of another class?</p> <p>I'm trying to get a Database instance inside my Model class (MVC app), by calling a static method of the Database class. The constructor of this Database class is private, in order to have a singleton pattern. But it seems to be interfering when I try to call the static method inside my Model class.</p> <p>When I set the Database constructor to public, it works. But then it's not really a singleton pattern anymore.</p> <p>Any suggestions?</p> <p><strong>Database class:</strong></p> <pre><code>class Database extends PDO { private static $instance; private $dsn; private $user; private $pass; public function __construct() { $this-&gt;dsn = DB_ENGINE .':host='. DB_HOST .';dbname='. DB_NAME; $this-&gt;user = DB_USER; $this-&gt;pass = DB_PASS; parent::__construct($this-&gt;dsn, $this-&gt;user, $this-&gt;pass); } public static function getInstance() { if (!isset(self::$instance)) { $object = __CLASS__; self::$instance = new $object; } return self::$instance; } /** * select * @param string $sql An SQL string * @param array $array Paramters to bind * @param constant $fetchMode A PDO Fetch mode * @return mixed */ public function select($sql, $fetchMode = PDO::FETCH_ASSOC, $array = array()) { $stmt = $this-&gt;prepare($sql); foreach ($array as $key =&gt; $value) { $stmt-&gt;bindValue("$key", $value); } $stmt-&gt;execute(); return $stmt-&gt;fetchAll($fetchMode); } /** * insert * @param string $table A name of table to insert into * @param string $data An associative array */ public function insert($table, $data) { ksort($data); $fieldNames = implode(', ', array_keys($data)); $fieldValues = ':' . implode(', :', array_keys($data)); $stmt = $this-&gt;prepare("INSERT INTO $table ($fieldNames) VALUES ($fieldValues)"); foreach ($data as $key =&gt; $value) { $stmt-&gt;bindValue(":$key", $value); } $stmt-&gt;execute(); } /** * update * @param string $table A name of table to insert into * @param string $data An associative array * @param string $where the WHERE query part */ public function update($table, $data, $where) { ksort($data); $fieldDetails = NULL; foreach ($data as $key=&gt; $value) { $fieldDetails .= "$key=:$key,"; } $fieldDetails = rtrim($fieldDetails, ','); $stmt = $this-&gt;prepare("UPDATE $table SET $fieldDetails WHERE $where"); foreach ($data as $key =&gt; $value) { $stmt-&gt;bindValue(":$key", $value); } $stmt-&gt;execute(); } /** * delete * * @param string $table * @param string $where * @param integer $limit * @return integer Affected Rows */ public function delete($table, $where, $limit = 1) { return $this-&gt;exec("DELETE FROM $table WHERE $where LIMIT $limit"); } } </code></pre> <p><strong>Model class:</strong></p> <pre><code>class Model { protected $db; public function __construct() { $this-&gt;db = Database::getInstance(); } } </code></pre>
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    1. COYou should be getting an error message, your code is invalid. You can't have a private constructor on a class that's inheriting a class with a public constructor, and PDO's constructor is public. Also, why would you want to make this a singleton in the first place?
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      1. USyannis
    2. COIndeed, I get a blank page using this. And I very much like the idea of being sure to only have one database connection. But I guess if I make a new Database object inside my Model class, it doesn't matter, right?
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    3. COA blank page? Oh my, you have [display_errors](http://www.php.net/manual/en/errorfunc.configuration.php#ini.display-errors) off, you should always have it on during development. Your code generates a fatal error that's rather descriptive, you would have immediately known what's the problem if you had seen the error. Also, set [error_reporting](http://www.php.net/manual/en/errorfunc.configuration.php#ini.error-reporting) to `E_ALL` while you're at it.
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