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PHP

Mandy Feeney
Mandy Feeney
17,499 Points
Posted by Mandy Feeney
Mandy Feeney
17,499 Points

PHP Pagination error

I am having trouble with getting my pagination code to work with redirecting when an invalid number gets put into the URL. I have my own portfolio site that shows projects I have done, so I have pagination added, which works but when I type in an invalid number into the URL, I get an error:

Warning: Cannot modify header information - headers already sent by (output started at /customers/9/9/8/monkey-in-designs.co.uk/httpd.www/inc/header.php:12) in /customers/9/9/8/monkey-in-designs.co.uk/httpd.www/projects/projects.php on line 32 The projects can not be displayed right now.

The pagination code I use to redirect follows treehouse's videos on pagination:

// Gets the page variable and sets the current page to it; Sets it to 1 if it is blank.
if(empty($_GET["page"])) {
    $current_page = 1;
} else {
    $current_page = $_GET["page"];
}

// Checks to make sure the current page is an integer and not a string; if a string then change to integer. 
$current_page = intval($current_page);

$project = new Project;

$no_of_projects = $project->count_projects();

$projects_per_page = 6;
$total_pages = ceil($no_of_projects / $projects_per_page);

// Re-directs if the page number is too high to the last page and if it's too low to the first page.
if($current_page > $total_pages){
    header("Location: ./?page=" . $total_pages);
} else if($current_page < 1){
    header("Location: ./");
}

1 Answer

Andrew Shook
Andrew Shook
31,709 Points
Andrew Shook
Andrew Shook
31,709 Points

Mandy, I know you posted this question a few days ago, but I figured better late than never with some help. The problem here looks like it has to do with some with space left at the end of a file. Specifically, at line 12 of your header.php file. With PHP, if you have a closing PHP tag, ?>, at the end of a file, anything after that is considered output. This includes a "newline". Here is an example of what I mean.

<?php
    //your php code
?>
                     //this blank space or newline at the end of the file will be interpreted as output and php will send a response header. This will make redirecting impossible.

vs this code with no whitespace after the closing php tag, which will prevent the problem you are having.

<?php
    //your php code
?>

Technically, is doesn't have to be a newline it could also be a tab or a space. The best way to prevent this is to omit the closing PHP tag at the end of files that will only be include in other files like you header.php, or a config file.