Invalid Dates when field in Oracle table is null

[wolves]

I have a field defined in a table as varchar2(8), and it's being used as a date field in my report, as a dimension.
In Impromptu, it's being converted as such:

number-to-date(string-to-number(fieldA))

So, in the table, unfortunately, some of the values are null. So in the PowerPlay Cube, the dimension is built with some valid dates, and the null values in the table are being read and shown in the cube as 'Invalid Dates'.

Is there a way to fix this in Impromptu or Transformer, I could not find one.

The other obvious choice would be to put all ZEROES in the table, but trying to avoid this option if possible, but a last resort.

Thanks in advance,

 

[drlex]

Can't you just change the field in Impromptu (or the iqd directly) so that the logic is
If fieldA <> NULL then number-to-date(string-to-number(fieldA))else ('2000-01-01')
or whatever date you want as a default?

soi la, soi carré