How to pass an Instant from a javascript app to a spring-data-rest API

Question

I have a spring-data-rest API and I create a query like so:

@Query("SELECT at FROM Transaction at WHERE at.transactionDate BETWEEN :start AND :end")
Page<AssetsTransaction> findAllByDates(
    @Param("start") Instant start,
    @Param("end") Instant end,
    Pageable pageable);

Where Transaction.transactionDate is an Instant type. how I should pass a date from a javascript app?

Answer 1

Typically timestamps are stored/transferred/etc. in one of two ways:

UNIX timestamps

This is just a number representing the number of seconds from a fixed time in the past (known as the UNIX epoch ).

Java has the Instant#getEpochSecond() method to obtain this value, and the Instant.ofEpochSecond() static method to create an Instant object from a timestamp.

Javascript has the Date type which can be instantiated from a timestamp ( new Date(timestamp * 1000) ), and transformed into a timestamp with difficulty .

ISO 8601 strings

This is just regular ASCII text with a standardised format, for example:

2018-11-21T22:25:58+00:00

You gain the advantage of timezone support with this method.

Java uses Instant#toString() to get an ISO 8601 string, and this slightly more verbose method to convert back:

Instant.from(DateTimeFormatter.ISO_OFFSET_DATE_TIME.parse(string));

Javascript does not have native support for timezones, but it can still produce an ISO-compliant string with Date#toISOString() and parse it back with the static Date.parse() .

Whichever way you go, you may wish to use an additional library on the javascript side to gain more control over your timestamps, if this is important to you.