How do I parse UTC and format to local time with Clojure's clojure.java-time library?

Question

I'm sure I'm missing something simple. The goal is to parse a string such as "20230227T010000Z" and then to print out the time in the local time zone.

(as-> "20230227T010000Z" X                        
      (jt/offset-date-time "yyyyMMdd'T'HHmmssX" X) ;#object[java.time.OffsetDateTime "0xf79e8a9" "2023-02-27T01:00Z"]
      (jt/with-offset X (jt/zone-offset))          ;#object[java.time.OffsetDateTime "0x41ec977e" "2023-02-27T01:00-05:00"]     
      (jt/format "hh:mm" X))                       ;"01:00"

This returns "01:00" even though (jt/zone-offset) returns "-05:00".

Answer 1

Make sure you're using the correct function:

with-offset

Sets the offset to the specified value ensuring that the local time stays the same.

(as-> "20230227T010000Z" X
      (jt/offset-date-time "yyyyMMdd'T'HHmmssX" X) 
      (jt/with-offset X -5)         
      (jt/format "hh:mm" X))
=> "01:00"

with-offset-same-instant

Sets the offset to the specified value ensuring that the result has the same instant.

(as-> "20230227T010000Z" X
      (jt/offset-date-time "yyyyMMdd'T'HHmmssX" X) 
      (jt/with-offset-same-instant X -5)         
      (jt/format "hh:mm" X))
=> "08:00"