MongoDB PHP OOP - Error Property of non-object -

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this question has answer here:

i trying use oop php access mongodb collection. yet on page returns nothing, when in apache error log states

php notice: trying property of non-object in main.php on line 22

here code i'm using: db.php

class db {     static $db = null;      static function getmongocon()     {         if (self::$db === null)         {             try {                 $m = new mongo('mongodb://{user}:{password}@{host}:{port}/{database}');              } catch (mongoconnectionexception $e) {                 die('failed connect mongodb '.$e->getmessage());             }             self::$db = $m;         }             else         {             return self::$db;         }     }    }

main.php

//load db files require_once('db.php');  class test{    public function __construct() {        echo $this->output();    }     public function output() {        $con=db::getmongocon();        $db=$con->database;        $test=$db->collection;        $n=$test->find();        print_r($n);    }  }  new test();

this works using procedural code, , have been able insert data in method - should work (i have removed database details here obvious security reasons).

note: have read this still not working.

it's simple mistake. you're using factory pattern, first time you're calling getmongocon method, it'll return null:

class db {//convention: upper-case classes     private static $_db = null;//using pattern public static bad idea     public static function getmongocon()     {//^^ best specify public/private/protected         if (self::$db === null)         {//first time called: true             try {                 //i'd assign immediatly here, hey...                 self::$db = new mongo('mongodb://{user}:{password}@{host}:{port}/{database}');                 $m = new mongo('mongodb://{user}:{password}@{host}:{port}/{database}');             }             catch (mongoconnectionexception $e)             {                 die('failed connect mongodb '.$e->getmessage());             }             self::$db = $m;         }         //!!leave out else fix!!         return self::$db;     } }

as can see, did leave out else, no matter value of self::$db was have return it. if was null, you'll never in else branch, contained return statement.
there no real reason throw-catch block. rely on db-connection code work, if doesn't just, there no backup afaik, let throw (and halt).

just completeness, here's how i'd write above code:

class db {     private static $_db = null;     public static function getmongocon($new = false)     {//allow connection, never know...         if (self::$_db === null)         {             self::$_db = new mongo('mongodb://{user}:{password}@{host}:{port}/{database}');         }         if (true === !!$new)         {             return new mongo('mongodb://{user}:{password}@{host}:{port}/{database}');         }         return self::$_db;         //or, short 'n messy:         return (!$new ? self::$_db : new mongo('mongodb://{user}:{password}@{host}:{port}/{database}'));     } }

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