this is an actual instance containing model-domain data for a given data type.
typically, this means that an object of this type represents a row of data
in your database.
fields are accessed or set using the `[] and `[]= operators; thus if your data-mapping
contained a field called "full_name," you would access it in this way:
myobject["full_name"]
data for an object may be cached so that subsequent requests to find an object by
id (primary key) or alternate key do not generate database requests. to alter this
behavior, see Fins.Model.DataObject.set_cachable .
Fins.Model.DataObject()->validate_on_update()