搜索表单阻止删除其他查询

html:

<form method="GET">
<input type="text" name="k" id="header-search" value="<?=$_GET["k"];?>"/>
<input type="submit" id="header-submit" value="&#xf2eb;" />
</form>

When current url is:

https://example.com/search/cats?b=5

After click on submit button it remove b query and show like this:

https://example.com/search/cats?k=sometext

But i want this result:

https://example.com/search/cats?b=5&k=sometext

I have other query like b, d and also c maybe add more in future, so this is not a static, maybe url have b maybe d or maybe c or maybe all together or maybe no one.

I tried this but looks like no changes:

action="<?=$_SERVER['REQUEST_URI'];?>"

You can add the variables inside hidden inputs:

<form method="GET">
<?php if(isset($_GET['b']){ ?>
    <input type="hidden" name="b" value="<?=$_GET["b"];?>"/>
<?php } ?>
<input type="text" name="k" id="header-search" value="<?php echo isset($_GET["k"]) ? $_GET["k"] : '';?>"/>
<input type="submit" id="header-submit" value="&#xf2eb;" />
</form>

However this solution will not work very well if you have many different types of variables that may or may not exist all the time. If you add all the variables as hidden, they will all be visible when you submit the form. To prevent this, you will need to check if the variables are isset() and only print them if they are.

Here is a solution that uses hidden fields and handles any amount of get parameters:

<form method="GET">  

<?php 
foreach($_GET as $key => $value){
    // do not make a hidden input for k, there is already a text input for k 
    if($key != 'k'){ 
        echo '<input type="hidden" name="'.$key.'" value="'.$value.'"/>';
    }
}
?>

<input type="text" name="k" id="header-search" value="<?php echo isset($_GET["k"]) ? $_GET["k"] : '';?>"/>
<input type="submit" id="header-submit" value="&#xf2eb;" />
</form>