Null representation needed when using converters in Vaadin 8 binder
TextFields
in Vaadin8 are no longer allowed to get a null
set as
value. This usually is no problem unless we use a Converter
for the
field binding. In that case a null
value about to be bound will
raise an assertion error. It also won't help if that field is bound
with asRequired
.
The solution in this case is to use withNullRepresentation
before
adding the Converter
in the binding builder. This adds another
converter at first, that turns null
values into "something" so the
real converter has to actually work.
See
https://github.com/christoph-frick/try-vaadin8/commit/8eee2ce6880b7a3dd4ce1526cf533ef356d3ec50
and