Completing a Blogger with PHP - Providing the blog processor with database connectivity (
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As I discussed in the previous section, the blog processor aggregates a simple MySQL wrapping class to have at its disposal the required capacity for handling all the database-related operations. As you’ll imagine, this functionality is easily achieved by coding a new pair of classes, which are shown below.
Take a look at their respective definitions, please:
// define 'MySQL' class
class MySQL{
private $conId;
private $host;
private $user;
private $password;
private $database;
private $result;
const OPTIONS=4;
public function __construct($options=array()){
if(count($options)!=self::OPTIONS){
throw new
Exception('Invalid number of connection parameters');
}
foreach($options as $parameter=>$value){
if(!$value){
throw new
Exception('Invalid parameter '.$parameter);
}
$this->
{$parameter}=$value;
}
$this->connectDB();
}
// connect to MySQL
private function connectDB(){
if(!$this->conId=mysql_connect($this-
>host,$this->user,$this->password)){
throw new
Exception('Error connecting to the server');
}
if(!mysql_select_db($this-
>database,$this->conId)){
throw new
Exception('Error selecting database');
}
}
// run query
public function query($query){
if(!$this->result=mysql_query
($query,$this->conId)){
throw new
Exception('Error performing query '.$query);
}
return new Result($this,$this->result);
}
}
// define 'Result' class
class Result {
private $mysql;
private $result;
public function __construct(&$mysql,$result){
$this->mysql=&$mysql;
$this->result=$result;
}
// fetch row
public function fetchRow(){
return mysql_fetch_assoc($this->result);
}
// count rows
public function countRows(){
if(!$rows=mysql_num_rows($this->result)){
throw new
Exception('Error counting rows');
}
return $rows;
}
// count affected rows
public function countAffectedRows(){
if(!$rows=mysql_affected_rows($this-
>mysql->conId)){
throw new
Exception('Error counting affected rows');
}
return $rows;
}
// get ID form last-inserted row
public function getInsertID(){
if(!$id=mysql_insert_id($this->mysql-
>conId)){
throw new
Exception('Error getting ID');
}
return $id;
}
// seek row
public function seekRow($row=0){
if(!is_int($row)||$row<0){
throw new
Exception('Invalid result set offset');
}
if(!mysql_data_seek($this->result,$row)){
throw new
Exception('Error seeking data');
}
}
}
All right, I think that the two classes listed above should be quite familiar to you, since I’ve been using them as part of different code samples in several PHP tutorials. With reference to these classes, you can see they offer a group of comprehensive methods for connecting to MySQL, running queries and handling result sets, which can be used inside the “BlogProcessor” class. Quite simple, right?
Obviously this isn’t rocket science, so let’s move on to the next section. We'll learn how to provide all the input forms included with the blog processor with a basic JavaScript validation mechanism, which adds a useful feature to the whole application.
To see how these client-side verification routines will be integrated with the blog application, please click on the link below and keep reading.
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