web/private_php/ams/autoload/pagination.php

   1 <?php
   2 /**
   3 * Handles returning arrays based on a given pagenumber.
   4 * By specifing a $_GET['pagenum'] or if not(page = 1 will be used) a few elements from a specific query will be returned. Not all elements have to be loaded into objects, only
   5 * the elements needed for that specific page, this is a good thing performance wise. This is done by passign the query to the constructor and specifying how many you want to display.
   6 * @author Daan Janssens, mentored by Matthew Lagoe
   7 */
   8 class Pagination{
   9
  10     private $element_array; /**< Array containing the elements that are extracted for that specific page number */
  11     private $last; /**< The last page number */
  12     private $current; /**< The current page number (read from $_GET['pagenum']) */
  13     private $amountOfRows;  /**< Total amount of rows that a query would return (if no limits would be used) */
  14
  15     /**
  16     * Constructor.
  17     * will fetch the correct elements that match to a specific page (specified by the $_GET['pagenum'] variable). The query has to be passed as a string to the function
  18     * that way it will only load the specific elements that are related to the pagenumber. The $params, parameter is optional and is used to pass the parameters for the query.
  19     * The result class will be used to instantiate the found elements with, their set() function will be called. The class  its getters can be later used to get the info out of the object.
  20     * @param $query the query to be paginated
  21     * @param $db the db on which the query should be performed
  22     * @param $nrDisplayed the amount of elements that should be displayed /page
  23     * @param $resultClass the elements that should be returned should be of that specific class.
  24     * @param $params the parameters used by the query (optional)
  25     */
  26     function __construct($query, $db, $nrDisplayed, $resultClass, $params = array()) {
  27         if (!(isset($_GET['pagenum']))){
  28             $this->current= 1;
  29         }else{
  30             $this->current= $_GET['pagenum'];
  31         }
  32
  33         //Here we count the number of results
  34         $db = new DBLayer($db);
  35         $rows = $db->execute($query, $params)->rowCount();
  36         $this->amountOfRows = $rows;
  37         //the array hat will contain all users
  38
  39         if($rows > 0){
  40             //This is the number of results displayed per page
  41             $page_rows = $nrDisplayed;
  42
  43             //This tells us the page number of our last page
  44             $this->last = ceil($rows/$page_rows);
  45
  46             //this makes sure the page number isn't below one, or more than our maximum pages
  47             if ($this->current< 1)
  48             {
  49                 $this->current= 1;
  50             }else if ($this->current> $this->last) {
  51                 $this->current= $this->last;
  52             }
  53
  54             //This sets the range to display in our query
  55             $max = 'limit ' .($this->current- 1) * $page_rows .',' .$page_rows;
  56
  57             //This is your query again, the same one... the only difference is we add $max into it
  58             $data = $db->execute($query . " " . $max, $params);
  59
  60             $this->element_array = Array();
  61             //This is where we put the results in a resultArray to be sent to smarty
  62             while($row = $data->fetch(PDO::FETCH_ASSOC)){
  63                 $element = new $resultClass();
  64                 $element->set($row);
  65                 $this->element_array[] = $element;
  66             }
  67         }
  68     }
  69
  70
  71     /**
  72     * return the number of the 'last' object attribute
  73     * @return the number of the last page
  74     */
  75     public function getLast(){
  76         return $this->last;
  77     }
  78
  79
  80     /**
  81     * return the number of the 'current' object attribute
  82     * @return the number of the current page
  83     */
  84     public function getCurrent(){
  85         return $this->current;
  86     }
  87
  88
  89     /**
  90     * return the elements array of the object
  91     * @return the elements of a specific page (these are instantiations of the class passed as parameter ($resultClass) to the constructor)
  92     */
  93     public function getElements(){
  94         return $this->element_array;
  95     }
  96
  97
  98     /**
  99     * return total amount of rows for the original query
 100     * @return the total amount of rows for the original query
 101     */
 102     public function getAmountOfRows(){
 103         return $this->amountOfRows;
 104     }
 105
 106     /**
 107     * return the page links.
 108     * (for browsing the pages, placed under a table for example) the $nrOfLinks parameter specifies the amount of links you want to return.
 109     * it will show the links closest to the current page on both sides (in case one side can't show more, it will show more on the other side)
 110     * @return an array of integerswhich refer to the clickable pagenumbers for browsing other pages.
 111     */
 112     public function getLinks($nrOfLinks){
 113         $pageLinks = Array();
 114         //if amount of showable links is greater than the amount of pages: show all!
 115         if ($this->last <= $nrOfLinks){
 116             for($var = 1; $var <= $this->last; $var++){
 117                 $pageLinks[] = $var;
 118             }
 119         }else{
 120             $offset = ($nrOfLinks-1)/2 ;
 121             $startpoint = $this->current - $offset;
 122             $endpoint =  $this->current + $offset;
 123
 124             if($startpoint < 1){
 125                 $startpoint = 1;
 126                 $endpoint = $startpoint + $nrOfLinks - 1;
 127             }else if($endpoint > $this->last){
 128                 $endpoint = $this->last;
 129                 $startpoint = $endpoint - ($nrOfLinks -1);
 130             }
 131
 132             for($var = $startpoint; $var <= $endpoint; $var++){
 133                 $pageLinks[] = $var;
 134             }
 135         }
 136         return $pageLinks;
 137     }
 138 }