feat: datetime, customize how "today" is calculated with grid buttons

[vitaldo1992]

Prerequisites

• I have read the Contributing Guidelines.
• I agree to follow the Code of Conduct.
• I have searched for existing issues that already include this feature request, without success.

Describe the Feature Request

If user has custom timezone (not the same as on device) we dont have ability to highlight the current day due to that timezone today

Describe the Use Case

We need a property "timezone" which will render current date due to that timezone. It could be passed as UTC offset in minutes with negative or positive value. and based on that calendar will render proper current date

Describe Preferred Solution

No response

Describe Alternatives

No response

Related Code

No response

Additional Information

No response

[liamdebeasi]

Thanks for the report. The datetime component intentionally does not manage timezone information as is noted in the docs: https://ionicframework.com/docs/api/datetime#time-zones

For your application, you should pass in the localized time to ion-datetime using the value property. For example, if the current UTC time is 07:30 and the user has a timezone offset of -04:00, then you would pass in 03:30. Can you give that a try and let me know if it works?

[vitaldo1992]

@liamdebeasi Thanks for quick feedback
as we ca see here - current day is 29 September - but for the timezone +10 it should be September 30.
ISO format doesn't help - "2022-09-25T22:47:20+10:00"
It is easy to manage data with other dates libraries but impossible to influence on the current day
https://stackblitz.com/edit/ionic-angular-v5-kvpxye?file=src/app/app.component.html

[liamdebeasi]

Can you give me an example of when you would want to render the date in a different timezone than what is set on the user's device?

[vitaldo1992]

@liamdebeasi Sure, common case. Admin wants to view the app from user account on users timezone.
Admin lives in USA and the user is from China

[vitaldo1992]

or the huge structure where there are a lot of departments from all the world, with different timezones and each department has its own timezone but user can be a part of a few departments and he should act in theirs timezones

[vitaldo1992]

@liamdebeasi property "timezone-offset"="+10:30" or "currentDateTime"="2022-09-30T22:47:20" would solve the problem

[liamdebeasi]

Would you expect that the time and date selection would then be relative to the custom timezone? For example, if you selected "16:00" would you expect that to really be "16:00+10:00"?

[vitaldo1992]

@liamdebeasi In our particular case it doesn't matter - we can handle output with help of Luxon, Moment or other libraries. And we dont need the time.
But intuitively it is better to stick the ISO 8601 format in UTC. And give the freedom to manipulate the dates as user wishes.
But in case if we need to have "ion-datetime-button" - coder would want to see the real localized date or at least to have ability to use separate mask or pipe to handle display relatively to the Timezone