How does \Magento\Config\Block\System\Config\Form\Field work?

dmitrii_fediuk · November 17, 2015, 6:28am

The \Magento\Config\Block\System\Config\Form\Field is the default frontend_model for a backend configuration form field.

As a frontend_model, it implements the \Magento\Framework\Data\Form\Element\Renderer\RendererInterface:

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/app/code/Magento/Config/Block/System/Config/Form/Field.php#L21


*
* @author     Magento Core Team <core@magentocommerce.com>
*
*/
namespace Magento\Config\Block\System\Config\Form;


/**
* @SuppressWarnings(PHPMD.CouplingBetweenObjects)
* @SuppressWarnings(PHPMD.NumberOfChildren)
*/
class Field extends \Magento\Backend\Block\Template implements \Magento\Framework\Data\Form\Element\Renderer\RendererInterface
{
   /**
    * Retrieve element HTML markup
    *
    * @param \Magento\Framework\Data\Form\Element\AbstractElement $element
    * @return string
    */
   protected function _getElementHtml(\Magento\Framework\Data\Form\Element\AbstractElement $element)
   {
       return $element->getElementHtml();

The interface considt of the single method render:

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/Data/Form/Element/Renderer/RendererInterface.php#L22


namespace Magento\Framework\Data\Form\Element\Renderer;


interface RendererInterface
{
/**
 * Render form element as HTML
 *
 * @param \Magento\Framework\Data\Form\Element\AbstractElement $element
 * @return string
 */
public function render(\Magento\Framework\Data\Form\Element\AbstractElement $element);
}

Here is the \Magento\Config\Block\System\Config\Form\Field implementation of the render method:

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/app/code/Magento/Config/Block/System/Config/Form/Field.php#L54


    // Disable element if value is inherited from other scope. Flag has to be set before the value is rendered.
    if ($element->getInherit() == 1 && $isCheckboxRequired) {
        $element->setDisabled(true);
    }


    $html = '<td class="label"><label for="' .
        $element->getHtmlId() .
        '">' .
        $element->getLabel() .
        '</label></td>';
    $html .= $this->_renderValue($element);


    if ($isCheckboxRequired) {
        $html .= $this->_renderInheritCheckbox($element);
    }


    $html .= $this->_renderScopeLabel($element);
    $html .= $this->_renderHint($element);


    return $this->_decorateRowHtml($element, $html);
}

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/app/code/Magento/Config/Block/System/Config/Form/Field.php#L81


 */
protected function _renderValue(\Magento\Framework\Data\Form\Element\AbstractElement $element)
{
    if ($element->getTooltip()) {
        $html = '<td class="value with-tooltip">';
        $html .= $this->_getElementHtml($element);
        $html .= '<div class="tooltip"><span class="help"><span></span></span>';
        $html .= '<div class="tooltip-content">' . $element->getTooltip() . '</div></div>';
    } else {
        $html = '<td class="value">';
        $html .= $this->_getElementHtml($element);
    }
    if ($element->getComment()) {
        $html .= '<p class="note"><span>' . $element->getComment() . '</span></p>';
    }
    $html .= '</td>';
    return $html;
}


/**
 * Render inheritance checkbox (Use Default or Use Website)

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/app/code/Magento/Config/Block/System/Config/Form/Field.php#L29-L32


protected function _getElementHtml(\Magento\Framework\Data\Form\Element\AbstractElement $element)
{
    return $element->getElementHtml();
}

So the \Magento\Config\Block\System\Config\Form\Field implementation of the render method is a decorator for the form element’s getElementHtml method.

dmitrii_fediuk · November 17, 2015, 6:37am