How to add a multiselect field to system config field table?

Question

I want to add a table to a config section, where one column is a multiselect field.

Code is simliar to https://www.integer-net.com/how-to-create-tables-in-magento-system-configuration/, but Magento only supports select (not multiselect) fields.

^{Similar to this, just add mutliselect field instead of text field}

---

Any ideas how to solve it?

Btw ... I'm pretty sure that a working solution was already posted at github/gist a long time ago as a Hackathon project, but I can't find it anymore ...

Answer 1

I haven't tested this, so I'm just taking a wild guess.
The link you mentioned from integer-net explains how to use a select field using a class Namespace_Module_Block_Config_Adminhtml_Form_Field_Country as renderer.

Using the same example, just add a new method to the renderer class (mentioned above)

public function getExtraParams()
{
    return ' multiple="multiple" ';
}

On the other hand, this might not work since for multiple selects you have too have the input name like name[] instead of name so you can receive an array via post or get from it.

If it does not work try to replace

   $this->addColumn('country_id', array(
        'label' => Mage::helper('namespace_module')->__('Country'),
        'renderer' => $this->_getRenderer(),
    ));

with

   $this->addColumn('country_id[]', array(
        'label' => Mage::helper('namespace_module')->__('Country'),
        'renderer' => $this->_getRenderer(),
    ));

Again, not sure this will work.
I'm just throwing out ideas that are simple to test and don't involve a lot of coding. Maybe you get lucky and one works.

---

Update

In the same class where you added the method getExtraParams try adding / changing the method setInputName.
Make it look like this:

public function setInputName($value)
{
    return $this->setName($value.'[]');
}

second Update

change the method _prepareArrayRow in your shippingCosts block (in the example) to this:

protected function _prepareArrayRow(Varien_Object $row)
{
    $countries = $row->getData('country_id');
    foreach ($countries as $country) {
        $row->setData(
            'option_extra_attr_' . $this->_getRenderer()
                ->calcOptionHash($country),
            'selected="selected"'
        );
    }
}

and it should work. And put back the column name from country_id[] to country_id.