Partial read-only view object. How to make it work?

Question

Hello,
is there a way to have a "partial" read-only view object, where some attributes are based on an EO and some others are extracted directly from a table with no corresponding EO?
On this view-object it should be possible to perform row insertions from an af:table, in a way that, after validation (i.e. a row selection change), the values on the attributes not based on the EO do not get lost, even if they do not have any attributes based on an EO.
On the other hand, if I use fake EO attributes ($none$) for those read-only attributes, their values will not gest lost after validation of the new interted rows, but in this case, when the table is first rendered on the page, the table shows empty values on those items, probably because the EO attributes are empty when the query is performed.
Note that It seems I cannot use Transient attributes where their value is calculated with a SQL statement, since it would mean I would have to perform an heavy SQL statement for every transient attribute.
Is there any other solution, I hope the problem is clear.

Answer 1

That solution does not cover the case where an attributed of one entity used as reference is calculated from a SQL expression with parameters involving the remaining attributes of the same entity.
For example consider a reference-only entity based on a table with one field T(COD). This entity has one more attribute other than COD itself, CALCULATED_VALUE.
How can I bind the attribute CALCULATED_VALUE to a SQL expression which is a function of COD: MyDBPackage.GetValue(COD, :environment), where :environment is bind variable?
The frameowork always give me JBO-exception , asking to specify IN or OUT for the variable.