class Serialized

class Serialized extends FieldPluginBase {
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['format'] = [
            'default' => 'unserialized',
        ];
        $options['key'] = [
            'default' => '',
        ];
        return $options;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        parent::buildOptionsForm($form, $form_state);
        $form['format'] = [
            '#type' => 'select',
            '#title' => $this->t('Display format'),
            '#description' => $this->t('How should the serialized data be displayed. You can choose a custom array/object key or a print_r on the full output.'),
            '#options' => [
                'unserialized' => $this->t('Full data (unserialized)'),
                'serialized' => $this->t('Full data (serialized)'),
                'key' => $this->t('A certain key'),
            ],
            '#default_value' => $this->options['format'],
        ];
        $form['key'] = [
            '#type' => 'textfield',
            '#title' => $this->t('Which key should be displayed'),
            '#default_value' => $this->options['key'],
            '#states' => [
                'visible' => [
                    ':input[name="options[format]"]' => [
                        'value' => 'key',
                    ],
                ],
            ],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateOptionsForm(&$form, FormStateInterface $form_state) {
        // Require a key if the format is key.
        if ($form_state->getValue([
            'options',
            'format',
        ]) == 'key' && $form_state->getValue([
            'options',
            'key',
        ]) == '') {
            $form_state->setError($form['key'], $this->t('You have to enter a key if you want to display a key of the data.'));
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function render(ResultRow $values) {
        $value = $values->{$this->field_alias};
        if ($this->options['format'] == 'unserialized') {
            return $this->sanitizeValue(print_r(unserialize($value), TRUE));
        }
        elseif ($this->options['format'] == 'key' && !empty($this->options['key'])) {
            $value = (array) unserialize($value);
            return $this->sanitizeValue($value[$this->options['key']]);
        }
        return $value;
    }

}