PHP Function: Remove a Query String Key=>Value

I needed something like this also in a projet.
This is what I came up with


$qStr = "varOne=1&varTwo=2&key_to_remove=3&varFour=4"; //$_SERVER['QUERY_STRING']
$key="key_to_remove";
parse_str($qStr,$ar);
echo http_build_query(array_diff_key($ar,array($key=>"")));
//Outputs : varOne=1&varTwo=2&varFour=4


Not sure what’s the performance difference though

I have a very similar function to yours, David, and it seems for nearly the same reason.

function remove_qs_key($url, $key) {
$url = preg_replace('/(?:&|(\?))' . $key . '=[^&]*(?(1)&|)?/i', "$1", $url);
return $url;
}

I would use preg_quote() on the key…

When do you need to remove a key from a query string? Just curious, since I never needed to and been using php quite long.

@Phil Pérusse:

I think unset will be much faster than array_diff if you’re only removing a few keys.

Hi,

I use a similar function sometimes – but it does more than just remove a certain key. The purpose of the function is to build the querystring entirely. It takes two parameters, one array containing keys (with values) that should be added to the querystring and one array containing keys that should be removed. Then it cycles through the current querystring and removes or keeps keys depending on the parameter and finally adds keys if there are any.

Maybe this approach isn’t as good in your case but I’ve found it to be quite useful when I have a site that’s depending on querystring entirely.

// trippo

the function don’t works if I want to remove first key of my query string

$query_string = “page=home&lang=it”;
echo remove_querystring_var($query_string,’page’); //not works
echo remove_querystring_var($query_string,’lang’); //works

thanks, that’s cool :)

Hi,

nice code, but it did not work for the first parameter, because the “?” should be escaped: “\?” to match.
See here: http://php.net/manual/de/function.preg-replace.php

if i add escape it works for me:

function remove_querystring_var($url, $key) {
$url = preg_replace(‘/(.*)(\?|&)’ . $key . ‘=[^&]+?(&)(.*)/i’, ‘$1$2$4′, $url . ‘&’);
$url = substr($url, 0, -1);
return $url;
}

echo remove_querystring_var(“http://www.thinkplexx.com/?errors=%0A%09The+password+field+is+empty.%3B”,”errors”);

Still that entire regex could be reduced to:

preg_replace(‘/(?:&|(\?))’ . $key . ‘=[^&]*(?(1)&|)?/i’, “$1″, $url);

I like the parse_str/http_query_build idea so I extended it to include the ability to remove an array of values and add an array of values.

function querystring($strQS, $arRemove, $arAdd = NULL)
{
parse_str($strQS, $arQS);
$arQS = array_diff_key($arQS, array_flip($arRemove));
$arQS = $arQS + $arAdd;
return http_build_query($arQS);
}

Example:
Current URL = http://www.example.com?one=1&two=2&three=3&four=4

$arR = array(‘two’, ‘four’);
$arA = array(‘five’ => 5, ‘six’ => 6);
echo querystring($_SERVER['QUERY_STRING'], $arR, $arA);

prints “one=1&three=3&five=5&six=6″

@Dustin Hansen: Dustin’s solution is the most elegant and I found the other solutions to have issues with parameter’s at the beginning and end of the query string – in my testing Dustin’s solution worked for parameters at all positions.

@Adam: Oh and just for making it even more condensed, shorten the whole function to this:

function remove_qs_key($url, $key) {
return preg_replace(‘/(?:&|(\?))’ . $key . ‘=[^&]*(?(1)&|)?/i’, “$1″, $url);
}

I had an array of checkbox values being passed in the querystring, and I don’t think these functions work for removing it.

I found it easier to just directly define the $_SERVER['QUERY_STRING'] by concatenating the $_GET[] variables I wanted to pass, and leaving out the ones I didn’t (the checkbox array)

I had an array of checkbox values being passed in the querystring, and I don’t think these functions work for removing it.

I found it easier to just directly define the $_SERVER['QUERY_STRING'] by concatenating the $_GET[] variables I wanted to pass, and leaving out the ones I didn’t (the checkbox array)