Datetime validation without offset should allow omission of Z zone designator

[MattSidor]

ISO-8601 allows datetime strings to not have any timezone offset or Z zone designator. In these instances, it is assumed to be in local time. (Reference: https://en.wikipedia.org/wiki/ISO_8601#Local_time_(unqualified))

However, the datetime validator currently marks these as invalid.

const schema = z.string().datetime() // offset: false is default behavior
console.log( schema.safeParse( '2022-01-01T00:00:00' ).success ) // false

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[bchrobot]

This is still an issue. I am still working on the draft PR for it.

[0xturner]

I've opened PR that adds optional support for local (unqualified) date times here #2913

[Pyrolistical]

My workaround is just to refine for now. This also makes seconds optional.

const Timestamp = z
  .string()
  .refine(
    (value) => /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}(:\d{2}(\.\d+)?)?$/.test(value),
    {
      message:
        "timestamp must be of the unqualified form yyyy-mm-ddThh:mm[:ss[.mmm]]",
    },
  );

Example on where unqualified timestamps can come from using upcoming TC39 Temporal

> Temporal.Now.plainDateTimeISO('UTC').toString()
'2023-11-25T03:56:32.870588264'
> Temporal.Now.plainDateTimeISO('UTC').toString({smallestUnit: 'minute'})
'2023-11-25T03:56'

[kornysietsma]

This is an issue as well for us, dealing with OpenAPI datetime fields.

We are using zod-to-openapi to build clients for services we use - it sees an OpenAPI schema like "type": "string", "format": "date-time" and turns it into z.string().datetime({ offset: true }) - which is technically correct.

But we have an API that actually returns a datetime with no trailing Z - so when we query it, the zodios API throws a validation error as it's not a valid ISO8601 (well, really rfc3339) datetime.

The root problem is that API - but having a workaround in Zod would be very useful.

[Armadillidiid]

Just encountered this same issue

[jcollum-nutrien]

This is almost a year old. Please prioritize this Zod team. I'm here because Zod validation is failing on dates coming from our ERP system. edit: we decided to just use a preprocess to fix the date, which isn't great...

[colinhacks]

This is available in canary and will land in Zod 3.23.

[plehnen]

If you also land here and wonder why this is closed but still doesn't work and there is nothing about it in the documentation:
add flag: { local: true }

This is mentioned (only) in the release notes for v3.23.0:
You can now allow unqualified (timezone-less) datetimes using the local: true flag.

const schema = z.string().datetime({ local: true });
schema.parse("2022-01-01T12:00:00"); // OK

[MattSidor]

Thanks for calling this out @plehnen. I opened a PR to update the docs: #3760