Fatal Error call to member function count() is non object - php

Question

I am trying to query a database using pdo, but I cant figure out the problem. I have created an init file for my db details and server details and config file for configuration and index file and DB file.
index.php
<?php
require_once 'core/init.php';
$user = Db::getInstance()->get('users',array('username', '=' , 'raja' ));
if($user->count())
{
echo "No user";
}
else{
echo "OK!";
}
?>
Db.php
<?php
class Db
{
private static $_instance = null;
private $_pdo,
$_query,
$_error=false,
$_results,
$_count=0;
private function __construct()
{
try
{
$this->_pdo =new PDO("mysql:host=" .Config::get('mysql/host') . ";dbname=" .Config::get('mysql/db'),Config::get('mysql/username'),Config::get('mysql/password'));
}
catch(PDOException $e)
{
die($e->getMessage());
}
}
public static function getInstance()
{
if (!isset(self::$_instance))
{
self::$_instance = new Db();
}
return self::$_instance;
}
public function query($sql,$params=array())
{
$this->_error = false;
if($this->_query = $this->_pdo->prepare($sql))
{
$x=1;
if (count($params))
{
foreach ($params as $param )
{
$this->_query->bindValue($x,$param);
$x++;
}
}
if ($this->_query->execute())
{
$this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ);
$this->_count = $this->_query->rowCount();
}
else
{
$this->error=true;
}
}
return $this;
}
public function action($action,$table,$where=array())
{
if(count($where) === 3)
{
$operators = array('=','<','>','>=','<=');
$field = $where[0];
$operator = $where[1];
$value = $where[2];
if(in_array($operator,$operators))
{
$sql = "{$action}FROM{$table} WHERE {$field} {$operator} ?";
if($this->query($sql,array($value))->error()){
return $this;
}
}
}
return false;
}
public function get($table,$where)
{
return $this->action('SELECT *', $table, $where);
}
public function delete($table,$where)
{
return $this->action('DELETE ', $table,$where);
}
public function error()
{
return $this->_error;
}
public function count()
{
return $this->_count;
}
}
?>
It reports a fatal error about not finding the count object:
Fatal error: Call to a member function count() on a non-object in
C:\xampp\htdocs\Student Management system\index.php on line 6

Answer 1

You want to declare the object -- just calling an instance from part of the object class returns just that, a non-complete object part. You're calling the function as if it's just a function rather than if it is part of the class as a whole, so then referencing any other parts of the class as a whole the logic is lost because PHP only views it as a get function alone.
To solve:
<?php
require_once 'core/init.php';
//here
$user = new Db();
$userSelect = $user->get('users',array('username', '=' , 'raja' ));
...
From this, $user is your object.
Sinlgeton
If you want to instead create the connection as a singleton, then each reference to a class method (~function) must be referenced with the singleton syntax - the reference to count() should therefore need to be rewritten into a Singleton syntax using :: instead of -> .
please read http://www.phptherightway.com/pages/Design-Patterns.html