DateOnly data example is not compatible to RFC 3339, section 5.6

[jarosmpost]

DateOnly is not compliant with RFC 3339, section 5.6, because the time zone is missing. It is not clear at what moment the change from one day to another happens.

[hiddenalpha]

Works perfectly fine here when using generated Java classes:

Maybe only affects .Net stuff?

[jarosmpost]

From https://github.com/swisspush/apikana/blob/develop/src/model/ts/default-types.ts:

/**
* <a href="https://swagger.io/docs/specification/data-models/data-types/#string">String @format date</a>,
* as defined by <a href="https://tools.ietf.org/html/rfc3339#section-5.6">RFC 3339, section 5.6</a>,
* for example: <code>2017-07-21</code>.
*/
export type DateOnly=string // @format date

The example is only 'yyyy-mm-dd' without time zone and this not compatible to RFC 3339, section 5.6.

[hiddenalpha]

Ah :) I missed that. We've a DateOnly not a DateTime as I thought.

---

(Edit: BTW: If a type representing "date-time" (eg including date, time and offset) is wanted, DateTime could be used which contains everything needed. this type would cover the full type of the named RFC)

---

Unluckily with DateOnly I guess the situation gets a bit trickier I think :|

Originally "DateOnly" was clearly defined to be the "full-date" part named in the linked spec. (See older default-types.ts). This way, the format "YYYY-mm-dd" even is the only valid format. As its definition was unmistakable (cited from RFC):

   ...
   date-fullyear   = 4DIGIT
   date-month      = 2DIGIT  ; 01-12
   date-mday       = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on
                             ; month/year
   ...
   full-date       = date-fullyear "-" date-month "-" date-mday
   ...

So there's neither timezone nor offset information involved in the "full-date" type. I've no idea why this detail got dropped from Apikana doc somewhen later.

---

Nevertheless I think the remaining question is: What is the correct way to store a DateOnly but including offset information. Actually I don't know such a format.

We usually only use "DateTime" even we're not interested in the time part. This might be the reason we never stumbled over this yet.

[lbovet]

DateOnly is precisely meant to refer to a date and not a point in time (datetime). The timezone is irrelevant.
It is not intended to be deserialized as a datetime but as a date. E.g. java.time.LoclalDate in Java.

[jarosmpost]

@lbovet : Okay. That's a good clue. I make a suggestion to improve the comment for DateOnly: #191.