How does \Magento\Framework\View\Layout::createBlock() work?

dmitry_fedyuk · November 17, 2015, 5:48am

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/View/Layout.php#L743


 *
 * @param string $type
 * @param string $name
 * @param array $arguments
 * @return \Magento\Framework\View\Element\AbstractBlock
 */
public function createBlock($type, $name = '', array $arguments = [])
{
    $this->build();
    $name = $this->structure->createStructuralElement($name, Element::TYPE_BLOCK, $type);
    $block = $this->_createBlock($type, $name, $arguments);
    $block->setLayout($this);
    return $block;
}


/**
 * Create block and add to layout
 *
 * @param string $type
 * @param string $name
 * @param array $arguments

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/View/Layout.php#L760


 *
 * @param string $type
 * @param string $name
 * @param array $arguments
 * @return \Magento\Framework\View\Element\AbstractBlock
 */
protected function _createBlock($type, $name, array $arguments = [])
{
    /** @var \Magento\Framework\View\Layout\Generator\Block $blockGenerator */
    $blockGenerator = $this->generatorPool->getGenerator(Layout\Generator\Block::TYPE);
    $block = $blockGenerator->createBlock($type, $name, $arguments);
    $this->setBlock($name, $block);
    return $block;
}


/**
 * Add a block to registry, create new object if needed
 *
 * @param string|\Magento\Framework\View\Element\AbstractBlock $block
 * @param string $name
 * @param string $parent

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/View/Layout/Generator/Block.php#L237


/**
 * Create block instance
 *
 * @param string|\Magento\Framework\View\Element\AbstractBlock $block
 * @param string $name
 * @param array $arguments
 * @return \Magento\Framework\View\Element\AbstractBlock
 */
public function createBlock($block, $name, array $arguments = [])
{
    $block = $this->getBlockInstance($block, $arguments);
    $block->setType(get_class($block));
    $block->setNameInLayout($name);
    $block->addData(isset($arguments['data']) ? $arguments['data'] : []);
    return $block;
}


/**
 * Create block object instance based on block type
 *
 * @param string|\Magento\Framework\View\Element\AbstractBlock $block

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/View/Layout/Generator/Block.php#L256


 *
 * @param string|\Magento\Framework\View\Element\AbstractBlock $block
 * @param array $arguments
 * @throws \Magento\Framework\Exception\LocalizedException
 * @return \Magento\Framework\View\Element\AbstractBlock
 */
protected function getBlockInstance($block, array $arguments = [])
{
    if ($block && is_string($block)) {
        try {
            $block = $this->blockFactory->createBlock($block, $arguments);
        } catch (\ReflectionException $e) {
            $this->logger->critical($e->getMessage());
        }
    }
    if (!$block instanceof \Magento\Framework\View\Element\AbstractBlock) {
        throw new \Magento\Framework\Exception\LocalizedException(
            new \Magento\Framework\Phrase('Invalid block type: %1', [$block])
        );
    }
    return $block;

A block should be an instance of \Magento\Framework\View\Element\AbstractBlock:

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/View/Layout/Generator/Block.php#L261-L265


if (!$block instanceof \Magento\Framework\View\Element\AbstractBlock) {
    throw new \Magento\Framework\Exception\LocalizedException(
        new \Magento\Framework\Phrase('Invalid block type: %1', [$block])
    );
}

github.com

magento/magento2/blob/2335247d4ae2dc1e0728ee73022b0a244ccd7f4c/lib/internal/Magento/Framework/View/Element/BlockFactory.php#L43


 * Create block
 *
 * @param string $blockName
 * @param array $arguments
 * @return \Magento\Framework\View\Element\BlockInterface
 * @throws \LogicException
 */
public function createBlock($blockName, array $arguments = [])
{
    $blockName = ltrim($blockName, '\\');
    $block = $this->objectManager->create($blockName, $arguments);
    if (!$block instanceof BlockInterface) {
        throw new \LogicException($blockName . ' does not implement BlockInterface');
    }
    if ($block instanceof Template) {
        $block->setTemplateContext($block);
    }
    return $block;
}
}

dmitry_fedyuk · November 17, 2015, 5:51am

See also How does \Magento\Framework\View\Layout::getBlockSingleton() work?