OOP - Problems with adapting some code

[chromis]

Hi there,

I've been reading an OOP book recently and it gives some nice Adaptor / Template patttern code to wrap around the php Mysql functions. I thought that I'd try and create a Simple Address book using similar methods, but I'm having some trouble with using the class functions (I'm new to OOP in PHP 5).

So far I've written a Contact Book class and a Contact class. The Contact Book class has add, edit, delete and display functions for manipulating and displaying data in a database. My intention is to use the DB_Mysql, DB_MysqlStateme nt and DB_Mysql_Prod classes which I lifted from the book for the database interactions.

The following are my ContactBook and Contact classes (contacts.inc.p hp):
[php]
<?php
/*
* A simple contact book class
* @package
* @author chromis
*/
class ContactBook {
protected $dbh;
protected $dbtable;
protected $name;

public function __construct($db h, $dbtable, $name) {
$this->dbh = $dbh;
$this->dbtable = $dbtable;
$this->name = $name;
$this->display();
}
public function add($contact) {
if(!is_resource ($this->dbh)) {
throw new Exception("Cont actBook: Database resource invalid.");
}
$query = "INSERT INTO " . $this->dbtable . " (name,email,add ress)
VALUES (
'" . mysql_escape_st ring($contact->getName()) . "',
'" . mysql_escape_st ring($contact->getEmail()) . "',
'" . mysql_escape_st ring($contact->getAddress() ) . "'
);";
$stmt = $this->dbh->execute($query );
}
public function edit($contact) {
}
public function delete($contact ) {
}
public function display() {
print("<h1>" . $this->name . " Contact Book</h1>\n");
print("<h2>Cont acts:</h2>\n");

$query = "SELECT name,email,addr ess FROM " . $this->dbtable;

// Fetch row results from query
$stmt = $this->dbh->execute($query );
//$ret = $this->dbh->fetch_row();
}
public function show_entry($ent ry_id) {
$query = "SELECT * FROM $dbtable WHERE entry_id = :1";
$stmt = $this->dbh->prepare($query )->execute($entry _id);
}
}
class Contact {
protected $name;
protected $email;
protected $address;

public function __construct() {
$this->name = $name;
$this->email = $email;
$this->address = $address;
}
public function getName() {
return $this->name;
}
public function getEmail() {
return $this->email;
}
public function getAddress() {
return $this->address;
}
}
?>[/php]

The classes lifted from the book (db.inc.php):

[php]
<?php
/*
* MySQL Database Handling Classes
*
* @package DB_Mysql
* @author chromis
*/
class DB_Mysql {
protected $user;
protected $pass;
protected $dbhost;
protected $dbname;
protected $dbh; // Database connection handle

public function __construct($us er, $pass, $dbhost, $dbname) {
$this->user = $user;
$this->pass = $pass;
$this->dbhost = $dbhost;
$this->dbname = $dbname;
$this->connect();
}
public function connect() {
$this->dbh = mysql_connect($ this->$dbhost, $this->$user, $this->$pass);
if(!is_resource ($this->dbh)) {
throw new Exception("Cann ot connect to database.");
}
if(!mysql_selec t_db($this->dbname, $this->dbh)) {
throw new Exception("Cann ot select database.");;
}
}
public function execute($query) {
if(!$this->dbh) {
$this->connect();
}
$ret = mysql_query($qu ery, $this->dbh);
if(!$ret) {
throw new Exception;
}
else if(!is_resource ($ret)) {
return TRUE;
}
else {
$stmt = new DB_MysqlStateme nt($this->dbh, $query);
$stmt->result = $ret;
return $stmt;
}
}
public function prepare($query) {
if(!$this->dbh) {
$this->connect();
}
return new DB_MysqlStateme nt($this->dbh,$query);
}
}
class DB_MysqlStateme nt {
protected $result;
protected $dbh;
public $query;
public $binds;

public function __construct($db h, $query) {
$this->query = $query;
$this->dbh = $dbh;
if(!is_resource ($dbh)) {
throw new Exception("Not a valid database connection");
}
}
public function fetch_row() {
if(!$this->result) {
throw new Exception("Quer y not executed");
}
return mysql_fetch_row ($this-result);
}
public function fetch_assoc() {
return mysql_fetch_ass oc($this-result);
}
public function fetchall_assoc( ) {
$retval = array();
while($row = $this->fetch_assoc( )) {
$retval[] = $row;
}
return $retval;
}
public function execute() {
$binds = func_get_args() ;
foreach($binds as $index => $name) {
$this->binds[$index + 1] = $name;
}
$cnt = count($binds);
$query = $this->query;
foreach($this->binds as $ph => $pv) {
$query = str_replace(":$ ph", "'".mysql_escap e_string($pv)." '",$query);
}
$this->result = mysql_query($qu ery, $this->dbh);
if(!$this->result) {
throw new MysqlException;
}
return $this;
}
}
/*
* Test class - an example of the Template pattern.
* Hides the database specific connection parameters in the previous classes.
*
*/
class DB_Mysql_Prod extends DB_Mysql {
protected $user = "***";
protected $pass = "***";
protected $dbhost = "***";
protected $dbname = "***";

public function __construct() {}
}
?>
[/php]

And the code to initialise them (index.php):

[php]
include("inc/db.inc.php");
include("inc/contacts.inc.ph p");

// Create new mysql db connection
$dbh = new DB_Mysql_Prod() ;

// Create contact book passing in db connection, db table and name of contact book
$myContactBook = new ContactBook($db h, "simple_address _book", "E-Simple");

[/php]

The function that I'm working on at the moment is the display function in the ContactBook class, what I'm trying to do is write a function correctly which retrieves the contacts from the database using the db classes and then displays them, first of all though i need to get the query statement to work:

[php]
public function display() {
print("<h1>" . $this->name . " Contact Book</h1>\n");
print("<h2>Cont acts:</h2>\n");

$query = "SELECT name,email,addr ess FROM " . $this->dbtable;

// Fetch row results from query
$stmt = $this->dbh->execute($query ); (query statement)
//$ret = $this->dbh->fetch_row();
}
[/php]

I'm getting the following error though:

Notice: Undefined variable: dbhost in D:\sites\eddy\php\simple-address-book\inc\db.inc.php on line 23
 
Fatal error: Cannot access empty property in D:\sites\eddy\php\simple-address-book\inc\db.inc.php on line 23

I can't work out why dbhost is not defined, I must be implementing the classes incorrectly, anyone any ideas?

Thanks,

chromis

[r035198x]

Remove the $ on $this->$dbhost to $this->dbhost

[chromis]

Heheh it was staring me in the face! Thanks!