Hidden properties

Some columns in database is needed to full description of mapping, but not required to business logic. This columns is declared as part of mapping named Column is selected from database, but not mapped on data object properties.

For example - XData can operate primary (PK) and foreign (FK) keys of business objects and work with master-detail references between them, but mapping to property of external references is not required to operate with key.

Second case - optimistic concurrency resolving (see concurrency resolving) required concurrency token field, but this field is not required to business logic.

Third example - when data is grouped, needed to declare some field to link with external reference, but in this case possibly we can`t include this field in SELECT expression because of GROUP BY syntax. This case is resolved by Hidden property of column declaration. When Hidden is true - column will be not included into SELECT expression of resulted SQL query.

Hidden properties description is various to static and dynamic mapping declaration methods.