Pass parameters via GET and include more parameters

Question

I have a consultation page, where several parameters can be included in this query. I would like to concatenate more parameters if there are already parameters in that query. In short, take the parameters that already exist and concatenate if the user chooses any more.

Ex: <a href="?sexo=m">Masculino</a> <a href="?cor=verde">Verde</a>

Answer 1

If query came by GET at an address similar to this:

http://site/page.php?b=1&c=2

And you want the link <a href="?cor=verde">Verde</a> receive together b=1&c=2, you can use $_SERVER['QUERY_STRING'].

For example:

<?php
//cria a variavel vazia
$qs = '';

//Verifica se QueryString é vazio, se não for então seta a variavel $qs
if (false === empty($_SERVER['QUERY_STRING'])) {
   //O & no final é para separar as variaveis
   $qs = $_SERVER['QUERY_STRING'] . '&';
}
?>

<a href="?<?php echo $qs; ?>cor=verde">Verde</a>

To avoid repeated values, you can use an array using parse_str and http_build_query:

<?php
$qs = '';

if (false === empty($_SERVER['QUERY_STRING'])) {
   $qs = $_SERVER['QUERY_STRING'] . '&';
}

//extrai a querystring para uma array/vetor
parse_str($qs, $output);

//Exibe o resultado
print_r($output);
?>

<?php
//Copia o output para não misturar os links
$link1 = $output;

//Cria o seu link com o valor cor=verde
$link1['cor'] = 'verde';
?>
<a href="?<?php echo http_build_query($link1); ?>"></a>

<?php
//Copia o output para não misturar os links
$link2 = $output;

//Cria o seu link com o valor sexo=m
$link2['sexo'] = 'm';
?>
<a href="?<?php echo http_build_query($link2); ?>"></a>

This will prevent something like:

?cor=verde&cor=verde

So first the user chooses cor=verde and the url goes like this:

./page.php?cor=verde

So he chooses sexo=m and the url goes like this:

./page.php?cor=verde&sexo=m

Answer 2

Use the & at the beginning of a new parameter.

   ....
    <a href="?sexo=m&cor=verde">Masculino e Verde</a>
    ....