How to create a custom admin form with multiselect type in magento 2?

Question

I created a custom module with a multiselect type input.

My InstallSchema.php file contains this for this field.

->addColumn(
    'elegible_products',
    \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
    500,
    ['nullable => false'],
    'Products'
)

My Main.php file looks like

$fieldset->addField(
    'elegible_products',
    'multiselect',
    [
        'label' => __('Products'),
        'title' => __('Products'),
        'name' => 'elegible_products',
        'values' => \Ayakil\FreeGift\Block\Adminhtml\Freegifts\Grid::getValueArray4(),
        'disabled' => $isElementDisabled
    ]
);

This is my Grid.php file

static public function getOptionArray4()
{
    $data_array = array(); 
    $data_array[0] = 'a1';
    $data_array[1] = 'a2';

    return($data_array);
}

static public function getValueArray4()
{
    $data_array = array();
    foreach(\Ayakil\FreeGift\Block\Adminhtml\Freegifts\Grid::getOptionArray4() as $k => $v) {
        $data_array[] = array('value' => $k, 'label' => $v);
    }

    return($data_array);
}

If i tried to save the form i am getting an error like below.

{"0":"Notice: Array to string conversion in /home/muja/www/ayakil-greens/vendor/magento/framework/DB/Adapter/Pdo/Mysql.php on line 3105","1"

How can add Multiselect in custom admin form and save the data and retrieve the data here?

Answer 1

It seems like in your save controller, you need to set multiselect's value as a string. For eg :

$data['elegible_products'] = implode(',',$data['elegible_products']);

And then, you need to save records.

Hope, It will helpful for you.