In the engine model, you can choose to make this information explicit on classes by enabling one or more platform attributes, characterized by the reserved prefix __.
The following platform attributes are available:
__id: a unique identifier;__createdby: the user who created the object;__createdon: the date and time the object was created;__lastmodifiedby: the user who made the last modification;__lastmodifiedon: the date and time of the last modification;__ownedby: the user who owns the object;__ownedon: the date and time when the user acquired ownership of the object.
A class to which all available platform attributes have been added
Platform attributes thus enabled, as for all attributes, can be referenced in Livebase expressions to define other derived attributes, or to define filters or Class warnings at the Application Schema level.
Platform attributes are automatically valued by Livebase and are therefore read-only information. Therefore, it is not possible to perform some of the operations normally allowed with native attributes:
- modify the data type;
- define integrity constraints (make the attribute required);
- define a unique constraint (
Make Unique); - impose restrictions on domain.
Enable a platform attribute #
Right-click on a class to open its Class menu and select New platform attribute; choose the platform attribute from the list.
