How to select predefined options in an custom form list-field?

Question

I'm trying to pre-select several options in a custom form field. I created a new JFormField which extends JFormFieldList and gets its values from my database. This is my current code:

protected function getOptions()
{
    $app   = JFactory::getApplication();
    $cid   = $app->input->get('cid' , null);
    $db    = JFactory::getDBO();
    $query = $db->getQuery(true);
    $query->select('cs.id, cs.name');
    $query->from($db->quoteName('#__asdasd', 'cs'));
    $db->setQuery((string) $query);
    $results = $db->loadObjectList();

    $options  = array();
    if ($results)
    {
        foreach ($results as $result)
        {
            $options[] = JHtmlSelect::Option($result->id, $result->name);
        }
    }

    // Merge any additional options in the XML definition.
    $options = array_merge(parent::getOptions(), $options);

    return $options;
}

This works perfectly, however I can't figure out how to preselect some of the entries. Basically, I just want to add "selected=selected" to some of the options.

Any clue how I can get this to work? I already read the API Documentation, however I find it to be confusing (https://api.joomla.org/cms-3/classes/JHtmlSelect.html#method_option). Is $optKey the Argument I'm looking for? If this is the case, what attributes do I have to pass in order for it to work?

Answer 1

I had to do the same thing. I copied the list form field code and changed it accordingly, so I have 2 functions:

• getInput()
• getOptions() which you have

In the getInput function, that's what actually creates the list. You'll see a line like the following (the genericlist is also stated in the page you linked to):

$html[] = JHtml::_('select.genericlist', $options, $this->name, trim($attr), 'value', 'text', $selected, $this->id);

The important argument here is $selected. $selected is an array populated from a query I perform finding all the values that are selected depending on the item selected.

So, $selected should be an array you pass to the genericlist generation to tell it which values should be selected.