Save multiple list custom field for component

Question

I 've created a custom form field type

class JFormFieldCategories extends JFormFieldList 
{

protected $type = 'categories';

public function getOptions() 
{
    $db = JFactory::getDBO();
    $categories=array();

    $sql = "select * from #__table";
    $db->setQuery( $sql );
    $results = $db->loadObjectList();
    if(count($results)>0)
    {
        foreach($results as $resc){
            $options[$resc->id] = $resc->description;
        }
    }

$options = array_merge(parent::getOptions(), $options);
            return $options;
   }
}

I have added the field to the form

<field name="discount_on_categories" type="categories" multiple="true" size="40"  />

This is a multiple select value. What shall i do to save the selected values to the database and show them when i edit the item?

Answer 1

I found the solution on this so i share it jsut in case someone else needs this. I've added part of code in 2 places. First on the table file, in bind function:

if (isset($array['discount_on_categories']) && is_array($array['discount_on_categories'])) {
        $registry = new JRegistry;
        $registry->loadArray($array['discount_on_categories']);
        $array['discount_on_categories'] = (string) $registry;
    }

and then in the model file:

        $registry = new JRegistry;
        $registry->loadString($item->discount_on_categories);
        $item->discount_on_categories = $registry->toArray();

The first part converts the field value to string so that to save it to the DB and the second part converts the string to an array so that to display the selected options of the field.

Answer 2

I think you're after the same thing than this question - check my answer here. I needed the same thing and after many hours come up with that solution