title: Isset with multi select dropdown and bootstrap
body: <p>I have a wordpress site with a search form that searches for posts based on the form field selections, for custom fields etc. It works fine, however on the search results page I have an exact copy of the form except that I am trying to preset the form selections based on the search query/url string.</p>
  
  <p>I am using a regular select dropdown and I have set it to "multiple" so that it can use bootstraps multiselect with the checkboxes. I've asked a similar question <a href="https://stackoverflow.com/questions/47557998/using-isset-with-checkboxes">HERE</a> but that was for checkboxes and even though the bootstrap multiselect uses checkboxes, I still have to work with the select dropdown first.</p>
  
  <p>So after trying several things, I've come close but have ran into several problems. In the code below I made notes to further explain exactly what I mean.</p>
  
  <pre><code>&lt;select name="property_type[]" id="pt-multi" class="form-control multi-select2" multiple="multiple"&gt;
  &lt;?php
  $terms = get_terms( "property-type", array( 'hide_empty' =&gt; 0 ) );
  $count = count($terms);
  
  if ( $count &gt; 0  ){
          echo "&lt;option value='Any'&gt;All&lt;/option&gt;";
  
          foreach ( $terms as $term ) {
  
  if (isset($_GET['property_type'])) {
          foreach ($_GET['property_type'] as $proptypes) {
  
  // FIRST EXAMPLE
  $selected .= ($proptypes === $term-&gt;slug) ? "selected" : "";  // shows first correct selected value but also selects everything after it up until the second correct value, which it doesn't select.
  //$selected = ($proptypes === $term-&gt;slug) ? "selected" : "";   // shows only last correct selected value
  //if ($proptypes === $term-&gt;slug) { $selected = 'selected'; }   // shows first correct selected value then selects every value after, even if it wasn't selected
  
  // SECOND EXAMPLE
  //$selected .= ($proptypes === $term-&gt;slug) ? "selected" : "";  // shows first correct selected value then selects every value after, even if it wasn't selected
  //$selected = ($proptypes === $term-&gt;slug) ? "selected" : "";   // shows only last correct selected value
  //if ($proptypes === $term-&gt;slug) { $selected = 'selected'; }   // shows first correct selected value then selects every value after, even if it wasn't selected
  
  
      } 
  }
        echo "&lt;option value='" . $term-&gt;slug . "' " . $selected . "&gt;" . $term-&gt;name . "&lt;/option&gt;";                  // FIRST EXAMPLE
  
        //echo "&lt;option value='" . $term-&gt;slug . "' " . ($selected?' selected':'') . "&gt;" . $term-&gt;name . "&lt;/option&gt;"; // SECOND EXMAPLE 
  
      }
  }
  ?&gt;
  &lt;/select&gt;
  </code></pre>