TYPO3 Core

When encoding an empty array as XML (e.g. an empty Flexform container from which all sections have been removed), the empty array will be encoded as (linebreaks stripped) <el index="el">        </el>. This leads to the object not being treated as an empty array on decoding, but as a nonempty string.

In some situations, such a non-empty string leads to undesirable results, e.g. when passing it to Fluid’s f:for view helper, where it will trigger a warning because it is not iterable.

The root cause can be found in GeneralUtility::array2xml(), where the value of array elements is prepended with indentation no matter the size of the array. Instead, empty elements should be dropped.

In most situations, the type="array" will mitigate the negative effects. For certain Flexform constellations however, this will not be used, making it impossible to resolve the type properly.