common-date-fields-semantics

Requires date-like properties in component schemas to use a string date or date-time format.

Attribute	Value
Category	Schema
Maturity	Gold
OpenAPI	Swagger 2.0; OpenAPI 3.0, 3.1, 3.2
Starter	Off
Lenient–Strict	Warning
Complete	Error

Intent

Explicit standard formats make date values unambiguous and usable by generators and validators.

Flags

A property under components.schemas when its lowercase name contains date, ends in _at, or is one of these common names: createdAt, modifiedAt, or updatedAt. It is reported unless it has type: string and format: date or date-time.

Does not flag

Correctly formatted date-like properties, unrelated property names, or schemas outside components.schemas.

See it fail

components:
  schemas:
    Payment:
      type: object
      properties:
        createdAt:
          type: string

Diagnostic: Date-like properties should use string format `date` or `date-time`.

Fix it

components:
  schemas:
    Payment:
      type: object
      properties:
        createdAt:
          type: string
          format: date-time

Use date for calendar dates and date-time when time is part of the value.

Configure

profiles:
  default:
    rules:
      extends: [recommended]
      override:
        common-date-fields-semantics: error

Nearby: string-schema-format-required.