I have found this (if I am understanding you correctly) to be a relatively common issue when converting to D2 from old styles of coding. In the past we would commonly use 'zero values' for things instead of 'null values'. In the common era of Entities, zero values are inappropriate. For example - in time fields a common practice was to enter `00:00:00` as a time meaning 'no time' - but Doctrine prefers (or requires) `null` values instead. This has required some reasonably serious recoding to accommodate such changes.