How to get and change URL variable PHP

Question

Hi could anyone help me with this I have a URL like

parent/child/a=1&b=2$c=3

then I have a link that would add variable to that URL

<a href="<?php echo $_SERVER["REQUEST_URI"]."&d=test1";?>">LINK 1</a>
<a href="<?php echo $_SERVER["REQUEST_URI"]."&d=test2";?>">LINK 2</a>

every time I click my link the variable d to URL keep on reproducing like this

parent/child/a=1&b=2&c=3&d=test2&d=test2&d=test2&d=test1&d=test1

I know that the $_SERVER["REQUEST_URI"] keep getting the current URL that is why I get that result. I have tried the some of properties of $_SERVER[""]. What I like is to change the d variable value, any idea how to do it. Any response is well appreciated.Thanks!

@Robert Podwika.I think that preg_replace will do but i don't know how to use that code, for now I will study that at manual of PHP. Thanks. I will hit +1 if the code fix my problem.Thanks Robert! — CaffeineShots
– CaffeineShots, Commented Apr 16, 2013 at 12:24

Michael Eugene Yuen · Accepted Answer · 2014-05-15 06:20:45Z

69

$query = $_GET;
// replace parameter(s)
$query['d'] = 'new_value';
// rebuild url
$query_result = http_build_query($query);
// new link
<a href="<?php echo $_SERVER['PHP_SELF']; ?>?<?php echo $query_result; ?>">Link</a>

answered May 15, 2014 at 6:20

Michael Eugene Yuen

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4 Comments

Overcode Over a year ago

This is a way better answer, I was looking for something like this. Thanks.

Brad Over a year ago

By far the most elegant solution I have seen posted across several similar questions

user1768761 Over a year ago

If rewriting of URLs is enabled (for example mod_rewrite), PHP_SELF will return the actual php file name, not the one seen in the url bar. It should work, but the link will change the path in the url bar.

TIH Over a year ago

This answer as written is insecure and will produces an XSS vulnerability.See cheatsheetseries.owasp.org/cheatsheets/…

Vinoth Babu · Accepted Answer · 2013-04-16 12:53:58Z

6

Try with the below expression, It Should Work

preg_replace("#&d=.*&#", '&d=newvalue&', $_SERVER['REQUEST_URI'])

edited Apr 16, 2013 at 12:53

answered Apr 16, 2013 at 12:36

Vinoth Babu

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3 Comments

CaffeineShots Over a year ago

yeah I am testing it right now. what is with the first parameter? "#&d=.*&#" is the number sign(#) and asterisk(*) is necessary? could i ask what is that for?

Vinoth Babu Over a year ago

Those are expression syntax. '&d=.*&' this is the thing what we want. It will replace the content &d=*& with what u give as second param. I have updated the code please check it again with new code.

PSZ_Code Over a year ago

Note to anybody finding this answer and trying it. This will NOT work if the variable you wish to change is the first variable due to the missing '&' sign in front.

ihorsl · Accepted Answer · 2017-02-27 20:27:17Z

6

modify_url_query($url, array('limit' => 50));

My function for modifying query in url

function modify_url_query($url, $mod){

$purl = parse_url($url);

$params = array();

if (($query_str=$purl['query']))
{
    parse_str($query_str, $params);

    foreach($params as $name => $value)
    {
        if (isset($mod[$name]))
        {
            $params[$name] = $mod[$name];
            unset($mod[$name]);
        }
    }
}        

$params = array_merge($params, $mod);

$ret = "";

if ($purl['scheme'])
{
    $ret = $purl['scheme'] . "://";
}    

if ($purl['host'])
{
    $ret .= $purl['host'];
}    

if ($purl['path'])
{
    $ret .= $purl['path'];
}    

if ($params)
{
    $ret .= '?' . http_build_query($params);
}    


if ($purl['fragment'])
{
    $ret .= "#" . $purl['fragment'];
}        

return $ret;

}

answered Feb 27, 2017 at 20:27

ihorsl

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1 Comment

Raha MK Over a year ago

It was working but getting undefined errors, how to fix that?

bklups · Accepted Answer · 2018-09-20 16:38:09Z

6

To remove repeated addition of query parameter do the below

// parse the url
$pathInfo = parse_url($_SERVER['REQUEST_URI']);
$queryString = $pathInfo['query'];
// convert the query parameters to an array
parse_str($queryString, $queryArray);
// add the new query parameter into the array
$queryArray['d'] = 1;
// build the new query string
$newQueryStr = http_build_query($queryArray);

// construct new url
?>
<a href="<?php echo $pathInfo['host'].'?'.$newQueryStr;?>">LINK 1</a>

edited Sep 20, 2018 at 16:38

bklups

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answered Apr 16, 2013 at 12:23

Venkat Kotra

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1 Comment

DoubleK Over a year ago

@CaffeineShots it should be parse_str($queryString, $queryArray); instead of $queryArray = parse_str($queryString); and $data is then $queryArray

Vikas Chauhan · Accepted Answer · 2018-09-10 11:38:13Z

3

function replaceUrlParameters($url = '', $newParams = array()){
    if($url){
        $urlArray = parse_url($url);
        $queryString = $urlArray['query'];
        parse_str($queryString, $queryParams);
        $queryParams = array_merge($queryParams, $newParams);
        $urlArray['query'] = http_build_query($queryParams);

        if(!empty($urlArray)){
            $url = $urlArray['scheme'].'://'.$urlArray['host'].$urlArray['path'].'?'.$urlArray['query'];
        }
    }
    return $url;
}
// $newParams = array of new parameters or old parameters with new value
$replacedUrl = replaceUrlParameters($url, $newParams);

Suppose you have url like :- <?php echo $_SERVER["REQUEST_URI"]."&a=test1&b=test2";?> and you want to replace parameter b's value to test3 then just pass this url and an array with the same index with new value. for ex- <?$url = $_SERVER["REQUEST_URI"]."&a=test1&b=test2";?> <? $newParams = ['b' => 'test3']?> then you will get - <? $_SERVER["REQUEST_URI"]."&a=test1&b=test3";?>

edited Sep 10, 2018 at 11:38

answered Jan 11, 2018 at 14:29

Vikas Chauhan

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2 Comments

Tim Visée Over a year ago

Please consider to explain what this code snippet does, and how to work with it. How does this solve the problem in the original question?

Vikas Chauhan Over a year ago

Edited my answer.

Code Lღver · Accepted Answer · 2013-04-16 12:34:17Z

0

Here you have not take care of the double quotation. Replace that with the following code and then check.

<a href="<?php echo 'http://'.$_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI'].'&d=test1';?>">LINK 1</a>

And also check in firebug that what URL is in href each time.

edited Apr 16, 2013 at 12:34

answered Apr 16, 2013 at 12:17

Code Lღver

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2 Comments

Jacob Tomlinson Over a year ago

I don't think that would make any difference?

CaffeineShots Over a year ago

@OSSCube.I tried it,in my end both double quote and single is doing fine,however I change it just to test your's, still reproducing the variable d sir, but thanks for reply anyway.

Pasi Matalamäki · Accepted Answer · 2019-11-30 10:51:24Z

Couldn't still find fitting solution myself, so created one..

static function changeParameters($url, $parameters)
{
    $urlParts = parse_url($url);


    $url = "";

    if (isset($urlParts['scheme'])) {
        $url .= $urlParts['scheme'] . "://";
    }

    if (isset($urlParts['host'])) {
        $url .= $urlParts['host'];
    }

    if (isset($urlParts['path'])) {
        $url .= $urlParts['path'];
    }

    $query = isset($urlParts['query']) ? $urlParts['query'] : "";

    $urlParameters = explode("&", $query);

    $urlParameterValuesByKey = new stdClass();

    foreach ($urlParameters as $urlParameter) {
        $equalsIndex = strrpos($urlParameter, "=");

        if ($equalsIndex) {
            $urlParameterValuesByKey->{substr($urlParameter, 0, $equalsIndex)} = substr($urlParameter, $equalsIndex + 1);
        } else {
            $urlParameterValuesByKey->{$urlParameter} = null;
        }
    }

    foreach ($parameters as $key => $value) {
        if(!is_string($value)) {
            unset($urlParameterValuesByKey->{$key});
        } else {
            $urlParameterValuesByKey->{$key} = $value;
        }
    }

    $query = "";

    foreach ($urlParameterValuesByKey as $key => $value) {
        if (strlen($query) === 0) {
            $query .= "?";
        }

        if (strlen($query) > 1) {
            $query .= "&";
        }
        if (is_string($value)) {
            $query .= $key . "=" . $value;
        } else {
            $query .= $key;
        }
    }


    $url .= $query;

    return $url;
}

Uses stdClass instead of associative array, because associative arrays does some funky stuff for the keys before setting them, as described here.

ratanmondal2313 · Accepted Answer · 2021-01-04 17:50:49Z

0

//for absolute path of the page. 
$actual_link = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "http") . "://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]"; 
//first delete the param 
$url = str_replace('&d='.$_GET["d"], '', $actual_link); 
//Now add this param again with it new value
$newUrl=$url.'&d=NewValueHere';
echo '<a href="'.$newUrl.'">Refresh to get new param value</a>';

answered Jan 4, 2021 at 17:50

ratanmondal2313

1

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