Extend MySQLi Class PHP - php

Question

I have downloaded the SafeMySQL class which I will post below. I would like to extend this database class to all of my other classes throughout the site that call queries. Currently, I have the main db connector set as a global variable, but I have to call it inside each class constructor and all of the class's methods. Surely there has to be an easier way?
Here is the DB class:
class SafeMySQL
{
private $conn;
private $stats;
private $emode;
private $exname;
private $defaults = array(
'host' => 'localhost',
'user' => '',
'pass' => '',
'db' => '',
'port' => NULL,
'socket' => NULL,
'pconnect' => FALSE,
'charset' => 'utf8',
'errmode' => 'error', //or exception
'exception' => 'Exception', //Exception class name
);
const RESULT_ASSOC = MYSQLI_ASSOC;
const RESULT_NUM = MYSQLI_NUM;
public function __construct($opt = array())
{
$opt = array_merge($this->defaults,$opt);
$this->emode = $opt['errmode'];
$this->exname = $opt['exception'];
if ($opt['pconnect'])
{
$opt['host'] = "p:".$opt['host'];
}
#$this->conn = mysqli_connect($opt['host'], $opt['user'], $opt['pass'], $opt['db'], $opt['port'], $opt['socket']);
if ( !$this->conn )
{
$this->error(mysqli_connect_errno()." ".mysqli_connect_error());
}
mysqli_set_charset($this->conn, $opt['charset']) or $this->error(mysqli_error($this->conn));
unset($opt); // I am paranoid
}
/**
* Conventional function to run a query with placeholders. A mysqli_query wrapper with placeholders support
*
* Examples:
* $db->query("DELETE FROM table WHERE id=?i", $id);
*
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return resource|FALSE whatever mysqli_query returns
*/
public function query()
{
return $this->rawQuery($this->prepareQuery(func_get_args()));
}
/**
* Conventional function to fetch single row.
*
* #param resource $result - myqli result
* #param int $mode - optional fetch mode, RESULT_ASSOC|RESULT_NUM, default RESULT_ASSOC
* #return array|FALSE whatever mysqli_fetch_array returns
*/
public function fetch($result,$mode=self::RESULT_ASSOC)
{
return mysqli_fetch_array($result, $mode);
}
/**
* Conventional function to get number of affected rows.
*
* #return int whatever mysqli_affected_rows returns
*/
public function affectedRows()
{
return mysqli_affected_rows ($this->conn);
}
/**
* Conventional function to get last insert id.
*
* #return int whatever mysqli_insert_id returns
*/
public function insertId()
{
return mysqli_insert_id($this->conn);
}
/**
* Conventional function to get number of rows in the resultset.
*
* #param resource $result - myqli result
* #return int whatever mysqli_num_rows returns
*/
public function numRows($result)
{
return mysqli_num_rows($result);
}
/**
* Conventional function to free the resultset.
*/
public function free($result)
{
mysqli_free_result($result);
}
/**
* Helper function to get scalar value right out of query and optional arguments
*
* Examples:
* $name = $db->getOne("SELECT name FROM table WHERE id=1");
* $name = $db->getOne("SELECT name FROM table WHERE id=?i", $id);
*
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return string|FALSE either first column of the first row of resultset or FALSE if none found
*/
public function getOne()
{
$query = $this->prepareQuery(func_get_args());
if ($res = $this->rawQuery($query))
{
$row = $this->fetch($res);
if (is_array($row)) {
return reset($row);
}
$this->free($res);
}
return FALSE;
}
/**
* Helper function to get single row right out of query and optional arguments
*
* Examples:
* $data = $db->getRow("SELECT * FROM table WHERE id=1");
* $data = $db->getOne("SELECT * FROM table WHERE id=?i", $id);
*
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return array|FALSE either associative array contains first row of resultset or FALSE if none found
*/
public function getRow()
{
$query = $this->prepareQuery(func_get_args());
if ($res = $this->rawQuery($query)) {
$ret = $this->fetch($res);
$this->free($res);
return $ret;
}
return FALSE;
}
/**
* Helper function to get single column right out of query and optional arguments
*
* Examples:
* $ids = $db->getCol("SELECT id FROM table WHERE cat=1");
* $ids = $db->getCol("SELECT id FROM tags WHERE tagname = ?s", $tag);
*
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return array|FALSE either enumerated array of first fields of all rows of resultset or FALSE if none found
*/
public function getCol()
{
$ret = array();
$query = $this->prepareQuery(func_get_args());
if ( $res = $this->rawQuery($query) )
{
while($row = $this->fetch($res))
{
$ret[] = reset($row);
}
$this->free($res);
}
return $ret;
}
/**
* Helper function to get all the rows of resultset right out of query and optional arguments
*
* Examples:
* $data = $db->getAll("SELECT * FROM table");
* $data = $db->getAll("SELECT * FROM table LIMIT ?i,?i", $start, $rows);
*
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return array enumerated 2d array contains the resultset. Empty if no rows found.
*/
public function getAll()
{
$ret = array();
$query = $this->prepareQuery(func_get_args());
if ( $res = $this->rawQuery($query) )
{
while($row = $this->fetch($res))
{
$ret[] = $row;
}
$this->free($res);
}
return $ret;
}
/**
* Helper function to get all the rows of resultset into indexed array right out of query and optional arguments
*
* Examples:
* $data = $db->getInd("id", "SELECT * FROM table");
* $data = $db->getInd("id", "SELECT * FROM table LIMIT ?i,?i", $start, $rows);
*
* #param string $index - name of the field which value is used to index resulting array
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return array - associative 2d array contains the resultset. Empty if no rows found.
*/
public function getInd()
{
$args = func_get_args();
$index = array_shift($args);
$query = $this->prepareQuery($args);
$ret = array();
if ( $res = $this->rawQuery($query) )
{
while($row = $this->fetch($res))
{
$ret[$row[$index]] = $row;
}
$this->free($res);
}
return $ret;
}
/**
* Helper function to get a dictionary-style array right out of query and optional arguments
*
* Examples:
* $data = $db->getIndCol("name", "SELECT name, id FROM cities");
*
* #param string $index - name of the field which value is used to index resulting array
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return array - associative array contains key=value pairs out of resultset. Empty if no rows found.
*/
public function getIndCol()
{
$args = func_get_args();
$index = array_shift($args);
$query = $this->prepareQuery($args);
$ret = array();
if ( $res = $this->rawQuery($query) )
{
while($row = $this->fetch($res))
{
$key = $row[$index];
unset($row[$index]);
$ret[$key] = reset($row);
}
$this->free($res);
}
return $ret;
}
/**
* Function to parse placeholders either in the full query or a query part
* unlike native prepared statements, allows ANY query part to be parsed
*
* useful for debug
* and EXTREMELY useful for conditional query building
* like adding various query parts using loops, conditions, etc.
* already parsed parts have to be added via ?p placeholder
*
* Examples:
* $query = $db->parse("SELECT * FROM table WHERE foo=?s AND bar=?s", $foo, $bar);
* echo $query;
*
* if ($foo) {
* $qpart = $db->parse(" AND foo=?s", $foo);
* }
* $data = $db->getAll("SELECT * FROM table WHERE bar=?s ?p", $bar, $qpart);
*
* #param string $query - whatever expression contains placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the expression
* #return string - initial expression with placeholders substituted with data.
*/
public function parse()
{
return $this->prepareQuery(func_get_args());
}
/**
* function to implement whitelisting feature
* sometimes we can't allow a non-validated user-supplied data to the query even through placeholder
* especially if it comes down to SQL OPERATORS
*
* Example:
*
* $order = $db->whiteList($_GET['order'], array('name','price'));
* $dir = $db->whiteList($_GET['dir'], array('ASC','DESC'));
* if (!$order || !dir) {
* throw new http404(); //non-expected values should cause 404 or similar response
* }
* $sql = "SELECT * FROM table ORDER BY ?p ?p LIMIT ?i,?i"
* $data = $db->getArr($sql, $order, $dir, $start, $per_page);
*
* #param string $iinput - field name to test
* #param array $allowed - an array with allowed variants
* #param string $default - optional variable to set if no match found. Default to false.
* #return string|FALSE - either sanitized value or FALSE
*/
public function whiteList($input,$allowed,$default=FALSE)
{
$found = array_search($input,$allowed);
return ($found === FALSE) ? $default : $allowed[$found];
}
/**
* function to filter out arrays, for the whitelisting purposes
* useful to pass entire superglobal to the INSERT or UPDATE query
* OUGHT to be used for this purpose,
* as there could be fields to which user should have no access to.
*
* Example:
* $allowed = array('title','url','body','rating','term','type');
* $data = $db->filterArray($_POST,$allowed);
* $sql = "INSERT INTO ?n SET ?u";
* $db->query($sql,$table,$data);
*
* #param array $input - source array
* #param array $allowed - an array with allowed field names
* #return array filtered out source array
*/
public function filterArray($input,$allowed)
{
foreach(array_keys($input) as $key )
{
if ( !in_array($key,$allowed) )
{
unset($input[$key]);
}
}
return $input;
}
/**
* Function to get last executed query.
*
* #return string|NULL either last executed query or NULL if were none
*/
public function lastQuery()
{
$last = end($this->stats);
return $last['query'];
}
/**
* Function to get all query statistics.
*
* #return array contains all executed queries with timings and errors
*/
public function getStats()
{
return $this->stats;
}
/**
* private function which actually runs a query against Mysql server.
* also logs some stats like profiling info and error message
*
* #param string $query - a regular SQL query
* #return mysqli result resource or FALSE on error
*/
private function rawQuery($query)
{
$start = microtime(TRUE);
$res = mysqli_query($this->conn, $query);
$timer = microtime(TRUE) - $start;
$this->stats[] = array(
'query' => $query,
'start' => $start,
'timer' => $timer,
);
if (!$res)
{
$error = mysqli_error($this->conn);
end($this->stats);
$key = key($this->stats);
$this->stats[$key]['error'] = $error;
$this->cutStats();
$this->error("$error. Full query: [$query]");
}
$this->cutStats();
return $res;
}
private function prepareQuery($args)
{
$query = '';
$raw = array_shift($args);
$array = preg_split('~(\?[nsiuap])~u',$raw,null,PREG_SPLIT_DELIM_CAPTURE);
$anum = count($args);
$pnum = floor(count($array) / 2);
if ( $pnum != $anum )
{
$this->error("Number of args ($anum) doesn't match number of placeholders ($pnum) in [$raw]");
}
foreach ($array as $i => $part)
{
if ( ($i % 2) == 0 )
{
$query .= $part;
continue;
}
$value = array_shift($args);
switch ($part)
{
case '?n':
$part = $this->escapeIdent($value);
break;
case '?s':
$part = $this->escapeString($value);
break;
case '?i':
$part = $this->escapeInt($value);
break;
case '?a':
$part = $this->createIN($value);
break;
case '?u':
$part = $this->createSET($value);
break;
case '?p':
$part = $value;
break;
}
$query .= $part;
}
return $query;
}
private function escapeInt($value)
{
if ($value === NULL)
{
return 'NULL';
}
if(!is_numeric($value))
{
$this->error("Integer (?i) placeholder expects numeric value, ".gettype($value)." given");
return FALSE;
}
if (is_float($value))
{
$value = number_format($value, 0, '.', ''); // may lose precision on big numbers
}
return $value;
}
private function escapeString($value)
{
if ($value === NULL)
{
return 'NULL';
}
return "'".mysqli_real_escape_string($this->conn,$value)."'";
}
private function escapeIdent($value)
{
if ($value)
{
return "`".str_replace("`","``",$value)."`";
} else {
$this->error("Empty value for identifier (?n) placeholder");
}
}
private function createIN($data)
{
if (!is_array($data))
{
$this->error("Value for IN (?a) placeholder should be array");
return;
}
if (!$data)
{
return 'NULL';
}
$query = $comma = '';
foreach ($data as $value)
{
$query .= $comma.$this->escapeString($value);
$comma = ",";
}
return $query;
}
private function createSET($data)
{
if (!is_array($data))
{
$this->error("SET (?u) placeholder expects array, ".gettype($data)." given");
return;
}
if (!$data)
{
$this->error("Empty array for SET (?u) placeholder");
return;
}
$query = $comma = '';
foreach ($data as $key => $value)
{
$query .= $comma.$this->escapeIdent($key).'='.$this->escapeString($value);
$comma = ",";
}
return $query;
}
private function error($err)
{
$err = __CLASS__.": ".$err;
if ( $this->emode == 'error' )
{
$err .= ". Error initiated in ".$this->caller().", thrown";
trigger_error($err,E_USER_ERROR);
} else {
throw new $this->exname($err);
}
}
private function caller()
{
$trace = debug_backtrace();
$caller = '';
foreach ($trace as $t)
{
if ( isset($t['class']) && $t['class'] == __CLASS__ )
{
$caller = $t['file']." on line ".$t['line'];
} else {
break;
}
}
return $caller;
}
/**
* On a long run we can eat up too much memory with mere statsistics
* Let's keep it at reasonable size, leaving only last 100 entries.
*/
private function cutStats()
{
if ( count($this->stats) > 100 )
{
reset($this->stats);
$first = key($this->stats);
unset($this->stats[$first]);
}
}
}
//HOW I'M CURRENTLY CONNECTING TO THE DATABASE & CREATING GLOBAL VAR
global $db;
$db = new SafeMySQL('localhost', 'user', 'password', 'database');
This is the class I would like to extend the above database class to:
class News
{
public $news_id;
var $author;
var $title;
var $body;
var $date;
var $comments_count;
function __construct($id)
{
global $db;
$row = $db->getRow('SELECT *
FROM news_articles
WHERE id = ?i', $id);
$this->news_id = $row[id];
$this->author = $row[author];
$this->title = $row[title];
$this->body = $row[body];
$this->date = $row[date];
$this->comments_count = $this->countComments();
}
public static function getAllArticles(){
global $db;
$all_articles_array = $db->getAll('SELECT id
FROM news_articles ORDER BY date DESC');
return $all_articles_array;
}

Answer 1

Please do not use the word 'extends'. It has a very special meaning and may confuse a reader. You rather need to 'use' another class' instance in this .
Although in my opinion using global keyword for the site-wide global variables is all right, you'd be teared in pieces if spotted by local 'global police'. So, it's safer to pass a $db object into constructor and assign it as a class property:
class News
{
public $news_id;
private $db;
var $author;
var $title;
var $body;
var $date;
var $comments_count;
function __construct($db, $id)
{
$this->db = $db;
$sql = 'SELECT * FROM news_articles WHERE id = ?i';
$row = $this->db->getRow($sql, $id);
$this->news_id = $row['id'];
$this->author = $row['author'];
$this->title = $row['title'];
$this->body = $row['body'];
$this->date = $row['date'];
$this->comments_count = $this->countComments();
}
public static function getAllArticlesIds()
{
$sql = 'SELECT id FROM news_articles ORDER BY date DESC';
return $thus->db->getCol($sql);
}
}
Note that I renamed the other method and used getCol() method here as you are selecting only one column.
However i don't quite understand why do you set some properties in the constructor. It seems you are confusing two classes - News and Article. It's for the single Article object you have to initialize it's properties in the constructor. While for the News I doubt it is the right way.

Answer 2

I'm not sure if I understand your problem. However, I notice that SafeMySql does not provide the connection handle. It might help to add this:
/**
* Function to get the connection handle.
* Addition to original SafeDB.
*
* Examples:
* mysqli_autocommit($db->getHandle(),FALSE);
* mysqli_commit($db->getHandle());
*
* #param string $getHandle - an SQL connection handle
* #return object
*/
public function getHandle()
{
return $this->conn;
}