Built-ins: time diff function

[andrehaland]

There are some use cases for calculating the difference between two Time values (e.g. calculate time since last login, or calculate the age based on birthdate). Is this something that would be accepted as an addition to the time built-ins?

output := time.diff(a, b)

Example implementation can be seen from this SO post:
https://stackoverflow.com/a/36531443

[ashutosh-narkar]

One way of doing this currently is something like https://play.openpolicyagent.org/p/ZDLf9k1fuC. The time-builtins use Go's time package. Feel free to add a new one !

[andrehaland]

One way of doing this currently is something like https://play.openpolicyagent.org/p/ZDLf9k1fuC

I should have been more specific. I was thinking of a difference on the format [years, months, days, hours, minutes, seconds]. The provided example only gives a duration, and when converting a duration to the wanted format we have to make some considerations, such as the number of days in a specific month etc., as described in the SO post:

https://stackoverflow.com/a/36531443

I am not sure if the required logic is possible to implement with Rego, so I will start on adding the new builtin. I was thinking of something like this:

./opa_darwin_amd64 eval 'diff := time.diff(time.parse_ns("2006-01-02", "2000-12-01"), time.now_ns())' --format=pretty
+-------------------+
|       diff        |
+-------------------+
| [20,4,6,10,10,21] |
+-------------------+

Any comments on this format @ashutosh-narkar?

[ashutosh-narkar]

This seems reasonable to me. Or even [hour, minute, second] which is what the Sub function in Go returns I believe should be fine as well.