Viewing file:  grid.class.php (5.21 KB) -rw-rw-rw-
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<?php
// load configuration file
require_once('config.php');
// start session
session_start();
// includes functionality to manipulate the products list
class Grid
{
// grid pages count
public $mTotalPages;
// grid items count
public $mItemsCount;
// index of page to be returned
public $mReturnedPage;
// database handler
private $mMysqli;
// database handler
private $grid;
// class constructor
function __construct()
{
// create the MySQL connection
$this->mMysqli = new mysqli(DB_HOST, DB_USER, DB_PASSWORD,
DB_DATABASE);
// call countAllRecords to get the number of grid records
$this->mItemsCount = $this->countAllRecords();
}
// class destructor, closes database connection
function __destruct()
{
$this->mMysqli->close();
}
// read a page of products and save it to $this->grid
public function readPage($page)
{
// create the SQL query that returns a page of products
$queryString = $this->createSubpageQuery('SELECT * FROM product',
$page);
// execute the query
if ($result = $this->mMysqli->query($queryString))
{
// fetch associative array
while ($row = $result->fetch_assoc())
{
// build the XML structure containing products
$this->grid .= '<row>';
foreach($row as $name=>$val)
$this->grid .= '<' . $name . '>' .
htmlspecialchars($val) .
'</' . $name . '>';
$this->grid .= '</row>';
}
// close the results stream
$result->close();
}
}
// update a product
public function updateRecord($id, $on_promotion, $price, $name)
{
// escape input data for safely using it in SQL statements
$id = $this->mMysqli->real_escape_string($id);
$on_promotion = $this->mMysqli->real_escape_string($on_promotion);
$price = $this->mMysqli->real_escape_string($price);
$name = $this->mMysqli->real_escape_string($name);
// build the SQL query that updates a product record
$queryString = 'UPDATE product SET name="' . $name . '", ' .
'price=' . $price . ',' .
'on_promotion=' . $on_promotion .
' WHERE product_id=' . $id;
// execute the SQL command
$this->mMysqli->query($queryString);
}
// returns data about the current request (number of grid pages, etc)
public function getParamsXML()
{
// calculate the previous page number
$previous_page =
($this->mReturnedPage == 1) ? '' : $this->mReturnedPage-1;
// calculate the next page number
$next_page = ($this->mTotalPages == $this->mReturnedPage) ?
'' : $this->mReturnedPage + 1;
// return the parameters
return '<params>' .
'<returned_page>' . $this->mReturnedPage . '</returned_page>'.
'<total_pages>' . $this->mTotalPages . '</total_pages>'.
'<items_count>' . $this->mItemsCount . '</items_count>'.
'<previous_page>' . $previous_page . '</previous_page>'.
'<next_page>' . $next_page . '</next_page>' .
'</params>';
}
// returns the current grid page in XML format
public function getGridXML()
{
return '<grid>' . $this->grid . '</grid>';
}
// returns the total number of records for the grid
private function countAllRecords()
{
/* if the record count isn't already cached in the session,
read the value from the database */
if (!isset($_SESSION['record_count']))
{
// the query that returns the record count
$count_query = 'SELECT COUNT(*) FROM product';
// execute the query and fetch the result
if ($result = $this->mMysqli->query($count_query))
{
// retrieve the first returned row
$row = $result->fetch_row();
/* retrieve the first column of the first row (it represents the
records count that we were looking for), and save its value in
the session */
$_SESSION['record_count'] = $row[0];
// close the database handle
$result->close();
}
}
// read the record count from the session and return it
return $_SESSION['record_count'];
}
// receives a SELECT query that returns all products and modifies it
// to return only a page of products
private function createSubpageQuery($queryString, $pageNo)
{
// if we have few products then we don't implement pagination
if ($this->mItemsCount <= ROWS_PER_VIEW)
{
$pageNo = 1;
$this->mTotalPages = 1;
}
// else we calculate number of pages and build new SELECT query
else
{
$this->mTotalPages = ceil($this->mItemsCount / ROWS_PER_VIEW);
$start_page = ($pageNo - 1) * ROWS_PER_VIEW;
$queryString .= ' LIMIT ' . $start_page . ',' . ROWS_PER_VIEW;
}
// save the number of the returned page
$this->mReturnedPage = $pageNo;
// returns the new query string
return $queryString;
}
// end class Grid
}
?>
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