HomeTom - CS: May 2011

This code can be easily ported to other languages. Note that the database used here is MSSQL, it has a paging function starting from version 2005 [1][2]. In MySQL, this can be achieved using 'Limit'.


<html>
<head><title>Test</title></head>
<body>
<h1>Test Paging</h1>
<?php 
// General variables for navBar.
$paging = new PagingClass( getService('getDataCount', array()), $_REQUEST['pg'] );
  
// Get data according to range.
$data = getService('getData', array('RangeStart' => $paging->getStart(), 'RangeEnd' => $paging->getEnd()));

// Output navBar and data.
print $paging->writeNavBar();
print Service2Table($data);
print $paging->writeNavBar();
?>

  
<?php

//
// @Author: HomeTom
// @Date: 5/26/2011
//
class PagingClass {  
    
    private $pageSize;
    private $pageButtonCount;
    private $totalCount;
    private $pageCount;
    private $currentPage;
    private $BaseUrl;
    
    //
    // Parameters:
    //   $totalCount: Total number of rows/records.
    //   $curPage: Current page index (usually passed as request parameter).
    // Preassumption: No parameter uses the name "pg", which is used for paging.
    //
    public function __construct($totalCount, $curPage) {
        $this->pageSize = 3;           // Default page size.
        $this->pageButtonCount = 4;    // Default number of paging buttons.

        $this->totalCount = $totalCount;
        $this->pageCount = ceil($totalCount / $this->pageSize);
      
        $this->currentPage = $curPage; 
        if ($this->currentPage == "") { $this->currentPage = 1; }
        else if ($this->currentPage < 0) { $this->currentPage = 0; }
        else if ($this->currentPage >= $this->pageCount) { $this->currentPage = $this->pageCount - 1; }
      
        // Base URL used by page links. Page parameter should be at the end. E.g. "index.php?pg="
        $baseUrl = $_SERVER['PHP_SELF'] . "?" . $_SERVER['QUERY_STRING'];
        if (preg_match("#pg=[0-9]*$#", $baseUrl) > 0) { 
          $this->BaseUrl = preg_replace("#pg=[0-9]*$#", "", $baseUrl) . "pg=";
        } else if ( empty($_SERVER['QUERY_STRING']) ) {
          $this->BaseUrl = $baseUrl . "pg=";
        } else {
          $this->BaseUrl = $baseUrl . "&pg="; 
        }
    }

    // Get start and end row/record number in current page.
    public function getStart() { return $this->currentPage * $this->pageSize + 1; }
    public function getEnd() { return (1 + $this->currentPage) * $this->pageSize; }
  
    //
    // Parameters:
    //   $PageCount: Total number of pages.
    //   $CurrentPageIndex: Current page index.
    //   $PageButtonCount: Number of page buttons to show on one page.
    //
    public function writeNavBar() {
        $PageCount = $this->pageCount;
        $CurrentPageIndex = $this->currentPage;
        $PageButtonCount = $this->pageButtonCount;
        $baseUrl = $this->BaseUrl; //"index.php?pg=";
    
        $DEBUG = 0;
        $lblNext = "Next";
        $lblPrev = "Prev";
        $lblFirst = "First";
        $lblLast = "Last";
    
        $s = "";

        if ($DEBUG) {
            print "pagecount: $PageCount, currentPageIndex: $CurrentPageIndex, ";
            print "PageButtonCount: $PageButtonCount<br>";
        }
  
        $startPage = (floor(($CurrentPageIndex)/$PageButtonCount) * $PageButtonCount);
        if ($DEBUG) print "startpage = $startPage<br>";
    
        $tmp = $PageCount - $PageButtonCount;
        if ($tmp > 0 && $tmp < $startPage) { $startPage = $tmp; }
    
        // First.
        if ($CurrentPageIndex == 0) { $s .= $lblFirst . " "; }
        else { $s .= "<a href=\"" . $baseUrl . "0\">" . $lblFirst . "</a> "; }
       
        // Prev.
        if ($CurrentPageIndex == 0) { $s .= $lblPrev . " "; }
        else 
        { 
            $j = $CurrentPageIndex - 1;
            $s .= "<a href=\"" . $baseUrl . $j . "\">" . $lblPrev . "</a> "; 
        }
      
        // ...
        if ($startPage > 0) { $s .= "<a href=\"" . $baseUrl . ($startPage - 1) . "\">...</a> "; }
    
        for ($i = 0; $i < $PageCount; $i ++) {
            if ($i < $startPage || $i >= $startPage + $PageButtonCount) { continue; }
            if ($i == $CurrentPageIndex) { $s .= " " . (1 + $i); }
            else { $s .= " <a href='" . $baseUrl . $i . "'>". (1 + $i) . "</a>"; }
        }
      
        // ...
        if ($startPage + $PageButtonCount <= $PageCount - 1) {
            $j = $PageButtonCount + $startPage;
            $s .= " <a href=\"" . $baseUrl . $j . "\">...</a> ";      
        }
      
        // Next.
        if ($CurrentPageIndex >= $PageCount - 1) { $s .= " " . $lblNext; } 
        else 
        {
            $j = $CurrentPageIndex + 1;
            $s .= " <a href=\"" . $baseUrl . $j . "\">" . $lblNext . "</a>";
        }
  
        // Last.
        if ($CurrentPageIndex >= $PageCount - 1) { $s .= " " . $lblLast; }
        else { $s .= " <a href=\"" . $baseUrl . ($PageCount - 1) . "\">" . $lblLast . "</a>"; }
  
        return $s;
    }  
}

//
// This function retrieves a web service return result.
// http://www.php.net/manual/en/soapclient.soapcall.php
//
// Parameters:
// $func: Name of the web service function.
// $params: Array of parameters used by this function.
//
function getService($func, $params) {
    try {
        $url = "http://localhost/test/TestService.asmx?WSDL";
        $client = new SoapClient($url);
        $result = $client->$func($params);
        //reset($result); // 'reset' sets the array pointer to the start of the array.
        // 'each' gets the current key/value pair into a separate array.
        list($key, $val) = each($result); 
        //print $key . ": " . $val . "<br>";
        return $val;
    } catch (Exception $e) {
        die ("<br><font color='red'>getService() error: " . $e->getMessage() . "</font><br>");
    }
} 


//
// This function converts web service return result into a table.
//
// rows are delimited by '\n', 
// cols are delimited by '\t'.
//
// explode() v.s. split():
// Biggest difference is explode() takes a delimiter to split by, 
// while split() takes a regular expression. explode is faster.
//
function Service2Table($val) {
    $row_delimiter = "\n";
    $col_delimiter = "\t";
    $DEBUG = 0;
  
    $v = ""; 
    $v_row = "";
    $rows = explode($row_delimiter, $val);
    $row_count = count($rows);
    if ($DEBUG) print "<br>row count: " . $row_count . "<br>";
    for ($i = 0; $i < $row_count; $i ++) {
        $s = $rows[$i];
        if ($s != "") {
            if ($DEBUG) print "$i. $s<br>";    
            $cols = explode($col_delimiter, $s);
            $col_count = count($cols);
            $v_row = "";
            for ($j = 0; $j < $col_count; $j ++) {
                $v_row .= "<td>" . $cols[$j] . " </td>";
            }
            $v .= "<tr>$v_row</tr>";
        }
    }
    $v = "<table border=1>$v</table>";
    return $v;
}

?>

</body>
</html>

On server side, the web service function (in C#) looks like this:


[WebMethod]
public string getData(int RangeStart, int RangeEnd) {
    string row_delimiter = "\n";
    string col_delimiter = "\t";

    string s = "";

    string connStr = ConfigurationManager.ConnectionStrings["LocalDB"].ConnectionString;
    SqlConnection conn = new SqlConnection(connStr);
    conn.Open();
    string sql =  @"with TmpDataTable AS 
        (SELECT *, ROW_NUMBER() OVER (ORDER BY JobID) as 'RowNum' FROM DataTable)
        SELECT * FROM TmpDataTable WHERE RowNum between " + RangeStart + " and " + RangeEnd;
    SqlCommand cmd = new SqlCommand(sql, conn);
    SqlDataReader sdr = cmd.ExecuteReader();

    int fieldCount = sdr.VisibleFieldCount;

    // get column names.
    s = sdr.GetName(0);
    for (int i = 1; i < fieldCount; i++)
    {
        s += col_delimiter + formatStr(sdr.GetName(i));
    }
    s += row_delimiter;

    if (sdr.HasRows) {
        // get column values.
        while (sdr.Read()) {
            s += sdr[0];
            for (int i = 1; i < fieldCount; i++) {
                s += col_delimiter + formatStr(sdr[i]);
            }
            s += row_delimiter;
        }
    }
    conn.Close();

    return s.Trim();
}

[1] Pagination in SQL Server
[2] retrieve specific range of rows in a SQL Server table

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