Datemust

Datemust is a term used in data validation to denote a constraint that a date value must satisfy. It is not tied to a specific technology; rather, it appears in form validation, database schemas, and rule engines as a way to codify date-related requirements.

Typical datemust criteria include presence (the field cannot be blank), format (the date must conform to a standard such as ISO 8601), and range constraints (the date must fall within a defined window). It can also include relational constraints with other dates (start_date must precede end_date) or calendar-based rules (no past dates, or only business days).

Implementation approaches vary: in relational databases through CHECK constraints; in API validation via JSON Schema or OpenAPI specifications; in application code via validation libraries or rule engines. Expressions are usually expressed as logical predicates combining field values and constants. Example: date must be between 2023-01-01 and 2025-12-31.

Common challenges include time zone handling, inclusive vs exclusive bounds, and localization of date formats. Proper error messages and testing strategies are essential to ensure datemust constraints support legitimate data without rejecting valid inputs.

Datemust relates to broader concepts such as data validation, constraints, and data quality.