Warning: Invalid argument supplied for foreach() in app/code/Magento/Config/Model/Config/Structure/Mapper/Sorting.php on line 34 (and my fix)

dmitrii_fediuk · November 27, 2015, 3:16am

My analysis and fix

Step 1

magento/magento2/blob/2.0.0/app/code/Magento/Config/Model/Config/Structure/Mapper/Sorting.php#L34


    }
    return $data;
}


/**
 * @param array $data
 * @return array
 */
protected function _processConfig($data)
{
    foreach ($data as &$item) {
        if ($this->_hasValue('children', $item)) {
            $item['children'] = $this->_processConfig($item['children']);
        }
    }
    uasort($data, [$this, '_cmp']);
    return $data;
}


/**
 * Compare elements

The $data is \n\t\t here. It is not an array so we have an exception.

Step 2

github.com

magento/magento2/blob/2.0.0/app/code/Magento/Config/Model/Config/Structure/Mapper/Sorting.php#L23


{
/**
 * Apply map
 *
 * @param array $data
 * @return array
 */
public function map(array $data)
{
    foreach ($data['config']['system'] as &$element) {
        $element = $this->_processConfig($element);
    }
    return $data;
}


/**
 * @param array $data
 * @return array
 */
protected function _processConfig($data)
{

The $element is \n\t\t here.
Look at the $data structure:

Step 3

github.com

magento/magento2/blob/2.0.0/app/code/Magento/Config/Model/Config/Structure/Converter.php#L64


 * @param \DOMNode $source
 * @return array
 */
public function convert($source)
{
    $result = $this->_convertDOMDocument($source);


    foreach ($this->_mapperList as $type) {
        /** @var $mapper MapperInterface */
        $mapper = $this->_mapperFactory->create($type);
        $result = $mapper->map($result);
    }


    return $result;
}


/**
 * Retrieve \DOMDocument as array
 *
 * @param \DOMNode $root
 * @return array|null

The problem line is:

github.com

magento/magento2/blob/2.0.0/app/code/Magento/Config/Model/Config/Structure/Converter.php#L59


}


/**
 * Convert dom document
 *
 * @param \DOMNode $source
 * @return array
 */
public function convert($source)
{
    $result = $this->_convertDOMDocument($source);


    foreach ($this->_mapperList as $type) {
        /** @var $mapper MapperInterface */
        $mapper = $this->_mapperFactory->create($type);
        $result = $mapper->map($result);
    }


    return $result;
}

Step 4

The wrong line is:

github.com

magento/magento2/blob/2.0.0/app/code/Magento/Config/Model/Config/Structure/Converter.php#L96


$child = $children->item($i);
$childName = $child->nodeName;
$convertedChild = [];


switch ($child->nodeType) {
    case XML_COMMENT_NODE:
        continue 2;
        break;


    case XML_TEXT_NODE:
        if ($children->length && trim($child->nodeValue, "\n ") === '') {
            continue 2;
        }
        $childName = 'value';
        $convertedChild = $child->nodeValue;
        break;


    case XML_CDATA_SECTION_NODE:
        $childName = 'value';
        $convertedChild = $child->nodeValue;
        break;

How to fix it:

Replace the wrong line with the new one:

if ($children->length && trim($child->nodeValue, "\n\t ") === '') {