DynamoDbAutoGeneratedTimestampAttribute custom date format and time zone

[chrisbloe-nhse]

Describe the feature

The @DynamoDbAutoGeneratedTimestampAttribute annotation allows an Instant to be stored in DynamoDB as a String, however, the format of this string is fixed to (e.g.) 2023-06-06T18:16:40.632760903Z.

I have a requirement to store the date in a different format e.g. 2023-06-06T18:16:40+01:00.

Use Case

I have tried the following:

    @DynamoDbAttribute("CreatedAt")
    @DynamoDbAutoGeneratedTimestampAttribute
    @DynamoDbUpdateBehavior(UpdateBehavior.WRITE_IF_NOT_EXISTS)
    @DynamoDbConvertedBy(OffsetDateTimeAsStringAttributeConverter.class)
    public OffsetDateTime getCreatedAt() {
        return createdAt;
    }

However @DynamoDbAutoGeneratedTimestampAttribute requires the method to return an Instant, leaving no easy way of specifying the format of the auto generated time.

Proposed Solution

A nice way to achieve this would be to allow the annotation user to specify a format and time zone e.g.

@DynamoDbAutoGeneratedTimestampAttribute(format=DateTimeFormatter.ISO_OFFSET_DATE_TIME, timezone="Europe/London")

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

AWS Java SDK version used

2.25.23

JDK version used

21.0.1

Operating System and version

N/A

[ungaratto93]

Hi, this feature can breaks who use a custom converter ?

[debora-ito]

Hi @chrisbloe-nhse thank you for raising this, acknowledged as a feature request.

One possible workaround is to use attribute converters - https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/ddb-en-client-adv-features-conversion.html

@ungaratto93 we'll keep custom attribute converters in mind when designing the feature, we avoid doing breaking changes in general.

[debora-ito]

@chrisbloe-nhse looks like this is already supported by using @DynamoDbConvertedBy together with @DynamoDbAutoGeneratedTimestampAttribute - see Use Cases 2 and 3 here: #2757.

For a code example, you can refer to the converters written for our internal tests: TimeFormatUpdateTestConverter.java, EpochMillisFormatTestConverter.java.

Let me know if this helps.