company logo

DBFieldDef :: get_initval - Initial value

Initial values are used for initializing new instances or transient attributes. The initial value can be defined as constant, only.

Initial values can be defined for members with elementary or complex data type. Complex data type members require an OIF string with initial values, which matches the structure of the complex data type.

More sophisticated initialization becomes possible via source definitions (for transient properties).

Persistent instances are initialized within the standard action DBInitialize(). Overloading the standard action in the structure context will disable the standard initialize function and the defined default values are not set.

If the function is not called with a valid database property definition, it throws an exception.

Notes:

Since system types do not generate data source information, calling a data source for a system type requires data source definition in this field. In order to refer to data source in this field, the expression must be preceded with @ (e.g. @FillData as initial value calls the FillData OSI function implemented in the class owning the member).

Return value:  String containing the text ( NString & )

Implementation details

const NString & DBFieldDef  :: get_initval (  )