How to stop URL query string from repeating?

Question

I'm using a URL query string to filter MySQL search results. When a user clicks on one of the links the query along with another variable is passed to the application, which then builds and executes a SQL query to the database.

The filtering works - the user can filter by genre, platform and can also sort at the same time, but the problem is that every time they click on a link it adds another variable at the end of $query.

For example if the user types in example and selects as filter, the genre action, the query looks like this:

keywords=example&genre=action

But lets say they then click on the adventure genre, the query then looks like this:

keywords=example&genre=action&genre=adventure

Is there a way to get the query to replace a variable if it isalready set?

$query = mysql_real_escape_string(htmlentities(trim($_SERVER[QUERY_STRING]))); 

<div id="filter_nav">
        <ul  id="nav_form">
            <li><h3 id="h3">Genre: &nbsp;</h3>
            <li><a href="search.php?'.$query.'&genre=Fighting">Fighting</a></li>
            <li><a href="search.php?'.$query.'&genre=Role-Playing">Role-Playing</a></li>
            <li><a href="search.php?'.$query.'&genre=Action">Action</a></li>
        </ul>
        <ul  id="nav_form">
            <li><h3 id="h3">Platform: &nbsp;</h3>
            <li><a href="search.php?'.$query.'&platform=Playstation 3">PS3</a></li>
            <li><a href="search.php?'.$query.'&platform=xbox 360">Xbox 360</a></li>
            <li><a href="search.php?'.$query.'&platform=Gamecube">Gamecube</a></li>
        </ul>
        </div>
        ';
        echo '
        <ul  id="sorting_form">
            <li><h3 id="h3">SORT BY: &nbsp;</h3>
            <li><a href="search.php?'.$query.'&order=title">Title</a></li>
            <li><a href="search.php?'.$query.'&order=release_date">Date</a></li>
            <li><a href="search.php?'.$query.'&order=rating">Rating</a></li>

        </ul>
        ';

function search_results($keywords){
$returned_results = array();
$where = "";

$keywords = preg_split('/[\s]+/', $keywords);
$total_keywords = count($keywords);

foreach($keywords as $key=>$keyword){
    $where .= "title LIKE '%$keyword%'";
    if($key != ($total_keywords - 1)){
        $where .= " AND ";
    }   
}
if (isset($_GET['platform']) && !empty($_GET['platform'])){
    $platform = mysql_real_escape_string(htmlentities(trim($_GET['platform']))); 
        $where .= " AND platform='$platform'";
    }

if (isset($_GET['genre']) && !empty($_GET['genre'])){
    $genre = mysql_real_escape_string(htmlentities(trim($_GET['genre']))); 
                $where .= " AND genre='$genre'";
}

if (isset($_GET['order']) && !empty($_GET['order'])){
    $order = mysql_real_escape_string(htmlentities(trim($_GET['order'])));
    $where .= " ORDER BY $order DESC";
    }

$results ="SELECT * FROM games WHERE $where ";

possible duplicate of keeping url parameters during pagination — hakre
– hakre, Commented May 5, 2012 at 16:38
Thanks i'll check out the post. I've been searching for a while i guess i was using wrong keywords. — hugoismyname
– hugoismyname, Commented May 5, 2012 at 16:50

jeroen · Accepted Answer · 2012-05-05 16:51:32Z

2

Using your code it can be done de-constructing the query string using parse_url and rebuilding it using http_build_query for every link.

However, personally I would just go for a form with 3 select boxes where the previously selected values are pre-selected.

You could put all your selection options in one multi-dimensional array and do a double loop.

Example:

<?php
$options = array(
  "genre" => array("Fighting", "Role-Playing", ...),
  ...
);
foreach $options as $key => $value)
{
?>
<select name="<?php echo $key; ?>">
<?php 
  foreach ($value as $item)
  {
    // echo option for item and mark it selected if necessary
  }
?>
</select>
<?php
}
?>

edited May 5, 2012 at 16:51

answered May 5, 2012 at 16:45

jeroen

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1 Comment

hugoismyname Over a year ago

Interesting, i'll try it out and get back to you. Thanks.

s.webbandit · Accepted Answer · 2012-05-05 16:38:14Z

-1

Modify every <a> tag like: <a href="search.php?'.$query.'&genre=Fighting">Fighting</a> to <a href="search.php?&genre=Fighting">Fighting</a>

I.e remove '.$query.' part.

answered May 5, 2012 at 16:38

s.webbandit

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2 Comments

hakre Over a year ago

Wouldn't that make you loose all the other parameters?

s.webbandit Over a year ago

is there a way to get the query to replace the variable if its already set?

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