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I have a class Database and Class User. My problem is that I want to create an instance of Database and use it throughout my classes.

Class User is just one of them. I want to be able to get the user record from the table using the database object. I don't want to create a database variable inside each class, because I will using sessions. Is there a solution?

class Database { /* * Edit the following variables */ private $db_host = 'localhost'; // Database Host private $db_user = 'root'; // Username private $db_pass = ''; // Password private $db_name = 'researchportal'; // Database /* * End edit */ private $con = false; // Checks to see if the connection is active private $result = array(); // Results that are returned from the query /* * Connects to the database, only one connection * allowed */ public function connect() { if(!$this->con) { $myconn = @mysql_connect($this->db_host,$this->db_user,$this->db_pass); if($myconn) { $seldb = @mysql_select_db($this->db_name,$myconn); if($seldb) { $this->con = true; return true; } else { return false; } } else { return false; } } else { return true; } } /* * Changes the new database, sets all current results * to null */ public function setDatabase($name) { if($this->con) { if(@mysql_close()) { $this->con = false; $this->results = null; $this->db_name = $name; $this->connect(); } } } /* * Checks to see if the table exists when performing * queries */ private function tableExists($table) { $tablesInDb = @mysql_query('SHOW TABLES FROM '.$this->db_name.' LIKE "'.$table.'"'); if($tablesInDb) { if(mysql_num_rows($tablesInDb)==1) { return true; } else { return false; } } } /* * Selects information from the database. * Required: table (the name of the table) * Optional: rows (the columns requested, separated by commas) * where (column = value as a string) * order (column DIRECTION as a string) */ public function select($table, $rows = '*', $where = null, $order = null) { $q = 'SELECT '.$rows.' FROM '.$table; if($where != null) $q .= ' WHERE '.$where; if($order != null) $q .= ' ORDER BY '.$order; $query = @mysql_query($q); if($query) { $this->numResults = mysql_num_rows($query); for($i = 0; $i < $this->numResults; $i++) { $r = mysql_fetch_array($query); $key = array_keys($r); for($x = 0; $x < count($key); $x++) { // Sanitizes keys so only alphavalues are allowed if(!is_int($key[$x])) { if(mysql_num_rows($query) > 1) $this->result[$i][$key[$x]] = $r[$key[$x]]; else if(mysql_num_rows($query) < 1) $this->result = null; else $this->result[$key[$x]] = $r[$key[$x]]; } } } return true; } else { return false; } } /* * Insert values into the table * Required: table (the name of the table) * values (the values to be inserted) * Optional: rows (if values don't match the number of rows) */ public function insert($table,$values,$rows = null) { if($this->tableExists($table)) { $insert = 'INSERT INTO '.$table; if($rows != null) { $insert .= ' ('.$rows.')'; } for($i = 0; $i < count($values); $i++) { if(is_string($values[$i])) $values[$i] = '"'.$values[$i].'"'; } $values = implode(',',$values); $insert .= ' VALUES ('.$values.')'; $ins = @mysql_query($insert); if($ins) { return true; } else { return false; } } } /* * Deletes table or records where condition is true * Required: table (the name of the table) * Optional: where (condition [column = value]) */ public function delete($table,$where = null) { if($this->tableExists($table)) { if($where == null) { $delete = 'DELETE '.$table; } else { $delete = 'DELETE FROM '.$table.' WHERE '.$where; } $del = @mysql_query($delete); if($del) { return true; } else { return false; } } else { return false; } } /* * Updates the database with the values sent * Required: table (the name of the table to be updated * rows (the rows/values in a key/value array * where (the row/condition in an array (row,condition) ) */ public function update($table,$rows,$where) { if($this->tableExists($table)) { // Parse the where values // even values (including 0) contain the where rows // odd values contain the clauses for the row for($i = 0; $i < count($where); $i++) { if($i%2 != 0) { if(is_string($where[$i])) { if(($i+1) != null) $where[$i] = '"'.$where[$i].'" AND '; else $where[$i] = '"'.$where[$i].'"'; } } } $where = implode('',$where); $update = 'UPDATE '.$table.' SET '; $keys = array_keys($rows); for($i = 0; $i < count($rows); $i++) { if(is_string($rows[$keys[$i]])) { $update .= $keys[$i].'="'.$rows[$keys[$i]].'"'; } else { $update .= $keys[$i].'='.$rows[$keys[$i]]; } // Parse to add commas if($i != count($rows)-1) { $update .= ','; } } $update .= ' WHERE '.$where; $query = @mysql_query($update); if($query) { return true; } else { return false; } } else { return false; } } /* * Returns the result set */ public function getResult() { return $this->result; } }

Class User:

<?php require_once 'class.database.php'; class User{ public $usr_id; public $usr_name; public $usr_level; public $last_access_login; public function __construct($id) { $this->usr_id = $id; //$this->usr_name = $usr_name; //$this->usr_level = $usr_level; $this->last_access_login = date("F d Y H:i:s.",time()); } public function getUser() { // $db->select('login_users','*','user_id='.$this->usr_id.''); // $res = $db->getResult(); // print_r($res); $this->usr_name = $res['username']; $this->usr_level = $res['user_level']; $this->last_access_login = date("F d Y H:i:s.",time()); } } $a = new User(3); $a->getUser(); ?>
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5 Answers 5

Reset to default
4

You will want to either pass $database to your user constructor or use a singleton like MrJ suggested up there.

Passing your database object as a parameter is pretty simple as you already know, but you make it clearer to others:

private $myDatabase = NULL; public function __construct(Database $myDatabase){ $this->myDatabase = $myDatabase; }

And then in the class anywhere you can use your database using

$this->myDatabase->select(...);

Creating the object now becomes as simple as:

$myUser = new User($database);

Obviously, adapt it as the need be :)

Singletons are also simple to use, create a static method inside your database class:

private static $staticInstance = NULL; public static function getInstance(){ if(Database::$staticInstance == NULL){ Database::$staticInstance = new Database(); Database::$staticInstance->connect(); } return Database::$staticInstance; }

This creates a function that automatically create your instance of the your unique database class as soon as you need it and return that single instance when you call the getInstance again.

To use this inside of your other classes simply call:

$mydb = Database::getInstance();

And then use your database object...

Singletons are really useful in many similar situations.

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4 Comments

Please don't skip the basic explanation because 90% of SO's traffic comes from search engines. Someone searching for this question may want those details.
private static $staticInstance = NULL; not private static $staticInstance = NULL: Typo
The database class has a connect function, which is mandatory to call after declaring the $mydb variable. How do I call it?
In the static function, add a connect call when it gets created... i'll add it to the example...
1

You probably will want to use a singleton class, for example, http://www.ricocheting.com/code/php/mysql-database-class-wrapper-v3 is one I personally use

Update

I'm not totally sure, but you may be able to include what you've done by:

$database = new Database(); $client = new User($id, $database);

Then within class User, and to __construct()

public function __construct($id, $database){ $this->db = $database; ... }

Then you should be able to call it like $this->db->... within class User (though I'm not too sure how to explain better, but this is an alternative that may/should work)

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0

You should have a look at the singleton pattern implementation. That way you'll be able to use your database class / connection from wherever you like.

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2 Comments

That is exactly what I mentioned - use a singleton (though you did give the full name :) )
Is this similar to a facad class?
0

Simply pass the object to the User class as a constructor argument.

new User(id, $db);
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0

Why not just extend your database class?

class.database.php

class Database extends ReflectionClass { protected $db; protected $_dbhost = DB_HOST; protected $_dbname = DB_NAME; protected $_dbpass = DB_PASS; protected $_dbuser = DB_USER; protected $_dboptions = array(PDO::ATTR_PERSISTENT => false); public function __construct() { parent::__construct($this); $dsn = "mysql:host=$this->_dbhost;dbname=$this->_dbname"; try { $this->db = new PDO($dsn, $this->_dbuser, $this->_dbpass, $this->_dboptions); $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } catch(Exception $e) { error_log(print_r($e->getMessage(),1).' '.__FILE__.' '.__LINE__,0); exit('Database is currently unavailable.'); } } public function __get($name) { if ($this->hasProperty($name)) return $this->$name; return null; } public function __set($name, $value) { if ($this->hasProperty($name)) $this->$name = $value; return null; } public function __destruct(){ $this->db = NULL; } public function select($tbl,$rows='*',$where=null,$order=null) { $q = 'SELECT '.$rows.' FROM '.$tbl; if(isset($where)) { $q .= ' WHERE '.$where; } if(isset($order)) { $q .= ' ORDER BY '.$order; } $q .= ' LIMIT 1'; $r = $this->db->prepare($q); foreach($this->getProperties() as $i=>$p){ if ($p->class===$this->name) { $prop = $p->name; $r->bindColumn($i+1,$this->$prop); } } $r->execute(); $n = $r->rowCount(); if($n) { $r->fetch(); } return $n; } } // end

class.users.php

class Users extends Database { protected $_id; protected $_name; protected $_level; public function __construct() { parent::__construct(); } public function selectUser($id) { $tbl = 'Users'; $rows = 'user_id,user_name,user_level'; $where = "user_id=$id"; $this->select($tbl,$rows,$where); } } // end

index.php

// config $C['DB_HOST'] = 'localhost'; $C['DB_NAME'] = 'db'; $C['DB_PASS'] = 'root'; $C['DB_USER'] = 'root'; foreach($C as $k=>$v) { define($k,$v); } // include require_once 'class.database.php'; require_once 'class.users.php'; // select $u = new Users(); $u->selectUser(1); echo $u->_id.'<br>'; echo $u->_name.'<br>'; echo $u->_level.'<br>';
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