title: How to send $_GET data as comma separated array
body: <p>I'm stumped on something which feels like it should be simple. I have three <code>&lt;select&gt;</code> inputs which need their values in the query string like this when submitting the form;</p>
  
  <p><code>domain.com/?filter=one,two,three</code></p>
  
  <p>Is this possible? How should I structure the form <code>name</code> attributes? I was also wondering if I can get the <code>$_GET</code> values server side after submission and create the array myself and set this as the page's URL, but wouldn't that technically be a redirect? </p>
  
  <p>Ideally this would be done with the query string so the URL can be copy and pasted or shared, it's not sensitive data either. Hopefully someone can help...some rough markup below;</p>
  
  <pre><code>&lt;form action="get"&gt;
     &lt;select name="filter[]"&gt;&lt;/select&gt;
     &lt;select name="filter[]"&gt;&lt;/select&gt;
     &lt;select name="filter[]"&gt;&lt;/select&gt;
     &lt;button type="submit&gt;Submit&lt;/button&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>..and there is a reason why all the <code>&lt;option&gt;</code> element are not in one <code>&lt;select&gt;</code>, it's not ideal, I know! Thanks</p>