core-bundle/src/Resources/contao/elements/ContentAlias.php
public function generate()
	{
		$objElement = ContentModel::findByPk($this->cteAlias);

		if ($objElement === null)
		{
			return '';
		}

		$strClass = static::findClass($objElement->type);

		if (!class_exists($strClass))
		{
			return '';
		}

		$objElement->origId = $objElement->id;
		$objElement->id = $this->id;
		$objElement->typePrefix = 'ce_';

		/** @var ContentElement $objElement */
		$objElement = new $strClass($objElement);

		$cssID = StringUtil::deserialize($objElement->cssID, true);

		// Override the CSS ID (see #305)
		if (!empty($this->cssID[0]))
		{
			$cssID[0] = $this->cssID[0];
		}

		// Merge the CSS classes (see #6011)
		if (!empty($this->cssID[1]))
		{
			$cssID[1] = trim($cssID[1] . ' ' . $this->cssID[1]);
		}

		$objElement->cssID = $cssID;

		return $objElement->generate();
	}
public function generate()
	{
		$objElement = ContentModel::findByPk($this->cteAlias);

		if ($objElement === null)
		{
			return '';
		}

		$strClass = static::findClass($objElement->type);

		if (!class_exists($strClass))
		{
			return '';
		}

		$objElement->origId = $objElement->id;
		$objElement->id = $this->id;
		$objElement->typePrefix = 'ce_';

		/** @var ContentElement $objElement */
		$objElement = new $strClass($objElement);

		$cssID = StringUtil::deserialize($objElement->cssID, true);

		// Override the CSS ID (see #305)
		if (!empty($this->cssID[0]))
		{
			$cssID[0] = $this->cssID[0];
		}

		// Merge the CSS classes (see #6011)
		if (!empty($this->cssID[1]))
		{
			$cssID[1] = trim($cssID[1] . ' ' . $this->cssID[1]);
		}

		$objElement->cssID = $cssID;

		return $objElement->generate();
	}
Parse the template

@return string