PHP add/modify a query string param & get the URL

Question

How can redirect the user back to the same page with the existing Query Strings but have 1 added/modified like "page".

I suppose 1 method is:

1. parse the $_SERVER['QUERY_STRING'] into an array
2. if page exists in the array, modify the value, else add it
3. use http_build_query to get the query string to append to $_SERVER['PHP_SELF']

but is there a better/more direct way?

Answer 1

Just to make sure you know about it, use parse_str to parse your query string:

<?php
parse_str($_SERVER['QUERY_STRING'], $query_string);
$query_string['page'] = basename($_SERVER['PHP_SELF']);
$rdr_str = http_build_query($query_string);

Answer 2

Using Jim Rubinstein's answer, I came up with a useful function that I thought I might share:

  function modQuery($add_to, $rem_from = array(), $clear_all = false){
  if ($clear_all){
     $query_string = array();
  }else{
     parse_str($_SERVER['QUERY_STRING'], $query_string);
  }
  if (!is_array($add_to)){ $add_to = array(); }
  $query_string = array_merge($query_string, $add_to);
  if (!is_array($rem_from)){ $rem_from = array($rem_from); }
  foreach($rem_from as $key){
     unset($query_string[$key]);
  }
  return http_build_query($query_string);
  }

For example: <a href="?<?=modQuery(array('kind'=>'feature'))?>">Feature</a>

Answer 3

If you want to receive both an absolute or a relative URI and replace one query string parameter (or even more), preserving whatever other parameter in the query string, like this:

// Get https://example.com?page=asdlol
echo uri_with_extra_params('https://example.com', [
    'page' => 'asdlol',
]);

// Get https://example.com?page=asdlol
echo uri_with_extra_params('https://example.com?page=old', [
    'page' => 'asdlol',
]);

// Get https://example.com?test=toast&page=asdlol
echo uri_with_extra_params('https://example.com?test=toast', [
    'page' => 'asdlol',
]);

// Get /homepage/?page=asdlol
echo uri_with_extra_params('/homepage/', [
    'page' => 'asdlol',
]);

To reach the above results, where the original URI is kept as-is (relative or absolute), just replacing the very specific query string parameters, you can use this function:

/**
 * Get an URI as-is, forcing one query string parameter or more. 
 *
 * @param $uri string  URI relative or absolute, with or without query string
 * @param $extra array Associative query string parameters to be added or replaced.
 * @return             URI relative or absolute, with the desired query string parameters
 */
function uri_with_extra_params(string $uri, array $extra): string
{
    // Get the URI and the query string.
    $url_parts = explode('?', $uri, 2);
    $url_without_query_string = $url_parts[0];
    $query_string_raw = $url_parts[1] ?? '';

    // Get the query string array data.
    $query_string_data = [];
    parse_str($query_string_raw, $query_string_data);

    // Force your new parameter(s).
    $query_string_data_new = array_replace($query_string_data, $extra);

    // Return the final URI in the desired language.
    return $url_without_query_string . '?' . http_build_query($query_string_data_new);
}

Example to rewrite the current request URI and forcing a specific page "p":

// If the page was http://localhost/?something=1&page=1,
//    get the page http://localhost/?something=1&page=2
$new_page = uri_with_extra_params($_SERVER['REQUEST_URI'], [
    'page' => '2',
] );

I like this solution because it keeps the rest of the query string as-is, and it works for both relative and absolute URIs.