requiredhasorder

Requiredhasorder is a constraint used in certain data modeling and validation frameworks to express that a container value is required and that its contained items must appear in a defined order. The term blends two concepts: required, meaning the value must be present, and hasOrder, indicating that the elements are not just present but arranged in a prescribed sequence. It is commonly applied to lists or collections where position carries meaning, such as workflow steps, ordered tasks, or version histories.

Semantics of the constraint typically require that when the parent container exists, it is non-empty and its elements adhere to the defined ordering. A violation can occur if the container is missing, if it is present but empty, or if the elements fail to follow the specified sequence. The exact interpretation can vary by framework, with some implementations tying the order to an explicit order field on each item and others using the items’ positions in the array.

Validation approaches include checking for presence of the container, ensuring a non-empty collection when required, and verifying that each element’s order value matches its position or a defined order key. In schema languages, requiredhasorder might be expressed through a composite annotation or via a combination of existing constraints, implemented with custom validators when not natively supported.

Examples often involve lists like steps in a recipe or stages in a process, where each item includes an order attribute and the sequence 1, 2, 3, and so on must be preserved. See also: required, hasOrder, ordered lists, schema validation.