Finally, virtual fields now working in string fields is just a collateral, it just happened because the steps are built in cascade blocks.

1. Fields
 a. empty ```$fields``` > all fields from ```Model->schema()``` already normalized
 b. !empty ```$fields``` > normalize fields ```_normalizeFields($fields)```

2. Virtual fields
 a. empty ```$fields``` > virtual fields from ```Model->getVirtualFields()``` already normalized
 b. !empty ```$fields``` > extract virtual fields ```Model->extractVirtualFields($fields)```