How best to populate a variable using Optional?

Question

I'm using an optional ID here but I don't like having to declare TWO variables to receive the data. What is a more concise way to accomplish this without having to declare an extra OptionalOrg variable?

    Optional<Organization> optionalOrg;
    Organization org;

    if (request.getOrgId() != null) {
        optionalOrg = organizationRepository.findById(request.getOrgId());
    } else {
        optionalOrg = organizationRepository.findById(DEFAULT_ORG);
    }

    if (optionalOrg.isPresent()) {
        org = optionalOrg.get();
    } else {
        throw new ClientException("Org not found);
    }

@OleV.V well I tend to agree Optional gains you nothing, but then why does JPA make findById return an Optional as the standard type for a repository? If I change the default method then I have tons of places through the codebase that also have to be changed? — dataman, Apr 27 '23 at 03:15
Sorry, missed that part. Sure, get an `Optional` from there. And use its `orElseThrow` method for getting its value or throwing your exception as shown in each of the answers. Don't use `isPresent()` and `get()`. — Ole V.V., Apr 27 '23 at 05:19
`Organization org = organizationRepository .findById(Objects.requireNonNullElse(request.getOrgId(), DEFAULT_ORG)) .orElseThrow(() -> new ClientException("Org not found"));` — Holger, Apr 29 '23 at 15:41

Silvio Mayolo · Answer 1 · 2023-04-26T23:55:57.917

4

orElseThrow can be used to get the contained value, or throw an exception of your choice if empty.

org = organizationRepository
  .findById(id)
  .orElseThrow(() -> new ClientException("Org not found"));

edited Apr 26 '23 at 23:55

answered Apr 26 '23 at 22:36

Silvio Mayolo

62,821
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It's been awhile since I've written Java code, but I'm pretty sure the arrow operator is supposed to be `->`, not `=>`. – StriplingWarrior Apr 26 '23 at 22:42
@StriplingWarrior Yep, you're right. Been awhile since I've written Java too :P – Silvio Mayolo Apr 26 '23 at 23:56

NoDataFound · Answer 2 · 2023-04-27T08:16:33.503

3

I would probably do that:

var orgId = Objects.requireNonNullElse(request.getOrId(), DEFAULT_ORG);
var org = organizationRepository.findById(orgId)
                                .orElseThrow(() ->  new ClientException("Org not found));

Use the appropriate type instead of var if not Java 11++ and similar function for requireNonNullElse.

edited Apr 27 '23 at 08:16

answered Apr 26 '23 at 22:37

NoDataFound

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The second line of code is good. The first line is not. Optional is *not* a general replacement for if/else (or `?`/`:`). See https://stackoverflow.com/questions/23454952/uses-for-optional for comments from Java’s designers on how Optional is intended to be used. – VGR Apr 27 '23 at 02:06

score 0 · Answer 3 · answered Apr 26 '23 at 22:42

0

try this but i'm not 100% sure..

Optional<Organization> optionalOrg = Optional.ofNullable(request.getOrgId())
    .flatMap(id -> organizationRepository.findById(id))
    .or(() -> organizationRepository.findById(DEFAULT_ORG));

Organization org = optionalOrg.orElseThrow(() -> new ClientException("Org not found"));

answered Apr 26 '23 at 22:42

Fabio Murtas

39
8

1

Now we’re at it, an alternative is `Optional .ofNullable(request.getOrgId()) .or(() -> DEFAULT_ORG) .flatMap(id -> organizationRepository.findById(id))`. It avoids the repetition of the call to `findById()`, so I would prefer it. – Ole V.V. Apr 27 '23 at 08:48
2

@OleV.V. it’s `orElseGet(() -> DEFAULT_ORG)`, as `or` expects a supplier of an optional, but for a simple variable access, I’d use `.orElse(DEFAULT_ORG)` instead of `.orElseGet(() -> DEFAULT_ORG)`… – Holger Apr 29 '23 at 15:43

How best to populate a variable using Optional?

3 Answers3