ThomasK ThomasK - 1 month ago 14
PHP Question

logic behind pagination like google

What is the logic behind google's pagination bahviour?

My paginator goes something like this:

[1] 2 3 ... 184 >
< 1 [2] 3 4 ... 184 >
< 1 2 [3] 4 5 ... 184 >
< 1 2 3 [4] 5 6 ... 184 >
< 1 ... 3 4 [5] 6 7 ... 184 >
< 1 ... 4 5 [6] 7 8 ... 184 >
< 1 ... 5 6 [7] 8 9 ... 184 >
< 1 ... 6 7 [8] 9 10 ... 184 >


Here is a live version of the above example: http://www.dev.thomaskile.me/?page=test-zone&module=Paginator.

I know why this is happening; I've set the amount of pagenumbers to be showen on each side of current page to two (2).

I would rather have the range of numbers to be equal like this:

[1] 2 3 4 5 6 7 8 ... 184 >
< 1 [2] 3 4 5 6 7 ... 184 >
< 1 2 [3] 4 5 6 7 ... 184 >
< 1 2 3 [4] 5 6 7 ... 184 >
< 1 ... 3 4 [5] 6 7 ... 184 >
< 1 ... 4 5 [6] 7 8 ... 184 >
< 1 ... 5 6 [7] 8 9 ... 184 >
< 1 ... 6 7 [8] 9 10 ... 184 >


It's at the beginning and the end I need to make som e changes, but can't figure out how to make it an easy operation...

I would like to make it flexible aswell. Meaning I would like to be able to change the number of wanted pages on each side, and have the script expand and claculate it all...

Here is my code so far:

/**
* page controller buttons
* @param str $this->querySting href="URL string"
* @param str $this->pageIdentifier $_GET['this-name']
* @param int $this->numPages Total amount of pages
* @param int $this->midRange Number of pages to show on each side of current page
*/

public function prevPage()
{
if ($this->currentPage > 1){
$prevPage = ($this->currentPage - 1);
return '<a href="'.$this->queryString.'&'.$this->pageIdentifier.'='.$prevPage.'" class="prev">prev</a>';
}
}
public function nextPage()
{
if ($this->currentPage < $this->numPages) {
$nextPage = $this->currentPage + 1;
return '<a href="'.$this->queryString.'&'.$this->pageIdentifier.'='.$nextPage.'" class="next">next</a>';
}
}
public function firstPage()
{
if ($this->currentPage > ($this->midRange + 1)) { // if number of pages between "currentPage" and "firstPage" exceeds $midRange with 1...
$firstPage .= '<a href="'.$this->queryString.'&'.$this->pageIdentifier.'=1" class="first">1</a>'; // ...show "first page"-link
if ($this->currentPage > ($this->midRange + 2)) { // if number of pages between $currentPage and "first page" exceeds $midRange with more than 1
$firstPage .= '&hellip;'; // add "..." between "1st page"-link and first page in $range
}
}
return $firstPage;
}
public function lastPage()
{
if ($this->currentPage < ($this->numPages - $this->midRange)) { // if number of pages between "currentPage" and "last page" is equal to $midRange
if (($this->currentPage < ($this->numPages - $this->midRange) - 1)) { // if number of pages between $currentPage and "last page" exceeds $range with more than two
$lastPage .= '&hellip;'; // add "..." between "last page"-link and last page in $range
}
$lastPage .= '<a href="'.$this->queryString.'&'.$this->pageIdentifier.'='.$this->numPages.'" class="last">'.$this->numPages.'</a>'; // show "last page"-link
}
return $lastPage;
}

# Range of pages between (prev first ...) and (... last next)
public function listPages()
{
for ($i = ($this->currentPage - $this->midRange); $i < (($this->currentPage + $this->midRange) + 1); $i++){
if (($i > 0) && ($i <= $this->numPages)) // if page number are within page range
{
if ($i == $this->currentPage) { $listPages .= '<a class="current">'.$i.'</a>'; } // if we're on current page
else { $listPages .= '<a href="'.$this->queryString.'&'.$this->pageIdentifier.'='.$i.'">'.$i.'</a>'; } // if not current page
}
}
return $listPages;
}

Answer

This is what I do for my Pagination.

$startPage = $currentPage - 4;
$endPage = $currentPage + 4;

if ($startPage <= 0) {
    $endPage -= ($startPage - 1);
    $startPage = 1;
}

if ($endPage > $totalPage)
    $endPage = $totalPage;

if ($startPage > 1) echo " First ... ";
for($i=$startPage; $i<=$endPage; $i++) echo " {$i} ";
if ($endPage < $totalPage) echo " ... Last ";

I believe my code is self-explained, but I will try to explain it in plain English. First of all, you need to know two things before you can generate Pagination: $totalPage and $currentPage.

Step 1: Assuming that the current page is in mid-range. $startPage and $endPage store range of page that pagination try to generate.

Step 2: If $startPage is negative, then you need to make-up for $endPage.

Step 3: If $endPage excess $totalPage, then $endPage is the last page.

Step 4: Generating Pagination into HTML. (it is up to you how you want your pagination to look. I will simply use plain text to represent my pagination)

if ($startPage > 1) echo " First ... ";
for($i=$startPage; $i<=$endPage; $i++) echo " {$i} ";
if ($endPage < $totalPage) echo " ... Last ";

Fixed flaw to my previous logic

$startPage = ($curPage < 5)? 1 : $curPage - 4;
$endPage = 8 + $startPage;
$endPage = ($totalPage < $endPage) ? $totalPage : $endPage;
$diff = $startPage - $endPage + 8;
$startPage -= ($startPage - $diff > 0) ? $diff : 0;

if ($startPage > 1) echo " First ... ";
for($i=$startPage; $i<=$endPage; $i++) echo " {$i} ";
if ($endPage < $totalPage) echo " ... Last ";
Comments