Magento 2 – How to Add Dropdown in Admin Form

adminformadminhtmlmagento-2.1magento2

I have set dropdown in form.xml like 

<argument name="data" xsi:type="array">
    <item name="options" xsi:type="string">Book\Flip\Model\Category\Attribute\Source\Category</item>
    <item name="config" xsi:type="array">
        <item name="dataType" xsi:type="string">text</item>
        <item name="label" translate="true" xsi:type="string">category</item>
        <item name="formElement" xsi:type="string">select</item>
        <item name="source" xsi:type="string">flip</item>
        <item name="sortOrder" xsi:type="number">20</item>
        <item name="dataScope" xsi:type="string">category</item>
        <item name="validation" xsi:type="array">
            <item name="required-entry" xsi:type="boolean">false</item>
        </item>
    </item>
</argument>

and create model

namespace Book\Flip\Model\Category\Attribute\Source;

    class Category extends \Magento\Eav\Model\Entity\Attribute\Source\AbstractSource
    {
        protected $_optionsData;

        public function __construct(array $options)
        {
            $this->_optionsData = $options;
        }

        public function getAllOptions()
        {
            if ($this->_options === null) {
                $this->_options = [
                    ['value' => '1', 'label' => __('science')]
                ];
            }
            return $this->_options;
        }
    }

But in admin form it's shown a blank dropdown.

Best Answer

Change Category class by following code:

namespace Book\Flip\Model\Source;

class Category implements \Magento\Framework\Option\ArrayInterface
{
    /**
     * Retrieve options array.
     *
     * @return array
     */
    public function toOptionArray()
    {
        $result = [];

        foreach (self::getOptionArray() as $index => $value) {
            $result[] = ['value' => $index, 'label' => $value];
        }

        return $result;
    }

    /**
     * Retrieve option array
     *
     * @return string[]
     */
    public static function getOptionArray()
    {
        return [1 => __('science')];
    }

    /**
     * Retrieve option array with empty value
     *
     * @return string[]
     */
    public function getAllOptions()
    {
        $result = [];

        foreach (self::getOptionArray() as $index => $value) {
            $result[] = ['value' => $index, 'label' => $value];
        }

        return $result;
    }

    /**
     * Retrieve option text by option value
     *
     * @param string $optionId
     * @return string
     */
    public function getOptionText($optionId)
    {
        $options = self::getOptionArray();

        return isset($options[$optionId]) ? $options[$optionId] : null;
    }
}
Related Topic