| Object Model > True DataControl Objects and Collections > Constraint Object, Constraints Collection |
A Constraints object represents a constraint that should be satisfied on field or record modification. It is basically a Boolean expression that is evaluated every time a modification occurs. It also contains error messages and an applicability condition expression.
True DataControl has two different collections of Constraint objects:
The Constraints collection is returned by the Constraints property of the TData control itself, which contains record-level constraints.
The Constraints collection returned by the Constraints:Field property of a Field object. Every data field can contain several constraints, which are called field-level constraints. If a field does not have constraints, its Constraints:Field collection is empty.
For more information, see Validation and Constraints.