How can I implement an add/edit parameter mechanism? - php

Question

Assume this is my current URL:
http://example.com/search?param1=foo&param2=bar
Now I want to add param3=baz. So this is the code:
<a href="?param3=baz" >add param3</a>
//=> http://example.com/search?param3=baz
See? param1 and param2 will be removed. So I have to handle it like this:
<?php
$query_str = parse_url($url, PHP_URL_QUERY);
parse_str($query_str, $query_params);
$query_params = $query_params == '' ? '?' : $query_params . '&';
?>
<a href="?{$query_params}param3=baz" >add param3</a>
Seems ugly, but ok, nevermind. Now what happens if a parameter be already exist and I need to edit it? Assume this example:
http://example.com/search?param1=foo&param2=bar
Now how can I make a link which edits the value of parame2? (plus keeping other parameters)

Answer 1

You can use function http_build_query to generate new query, like this:
$url = 'http://example.com/search?param1=foo&param2=bar';
$query_str = parse_url($url, PHP_URL_QUERY);
parse_str($query_str, $params);
$data = [
'param3' => 'baz'
];
$params = array_merge($params, $data);
echo http_build_query($params) . "\n";
And output will be:
param1=foo&param2=bar&param3=baz
I use array_merge for override exist params, if we get url:
$url = 'http://example.com/search?param1=foo&param3=bar';
The same code output will be:
param1=foo&param3=baz
We override exist param and save old params.

Answer 2

There is no way to write a relative URI that preserves the existing query string while adding additional parameters to it.
You have to Do again:
search?param1=foo&param=bar&param3=baz
Or
Using Javascript is Possible
How to add a parameter to the URL?
Or
function currentUrl() {
$protocol = strpos(strtolower($_SERVER['SERVER_PROTOCOL']),'https') === FALSE ? 'http' : 'https';
$host = $_SERVER['HTTP_HOST'];
$script = $_SERVER['SCRIPT_NAME'];
$params = $_SERVER['QUERY_STRING'];
return $protocol . '://' . $host . $script . '?' . $params;
}
Then add your value with something like;
echo currentUrl().'&param3=baz';
or
Whatever GET parameters you had will still be there and if param3 was a
parameter before it will be overwritten, otherwise it will be included
at the end.
http_build_query(array_merge($_GET, array("param3"=>"baz")))