CODEWITHSUNDEEP
java
robert trudel
robert trudel

Reputation: 5749

How to return a value depending on whether an Optional value is present or not?

I use Optional in a controller

@GetMapping(value = "/address/{id}")
public ResponseEntity<Addresses> getAddressById(@PathVariable("id") Integer id) {

    Optional<Address> address = addressService.getAddressById(id);
    return new ResponseEntity(address.get(), address.isPresent() ? HttpStatus.OK : HttpStatus.NOT_FOUND);
}

Actually, if there is no value, i get

java.util.NoSuchElementException: No value present
    at java.util.Optional.get(Optional.java:135) ~[na:1.8.0_131]

not sure if it's a good way to manage thing.

is there any good pratice

Upvotes: 1

Views: 2401

Answers (2)

Andreas
Andreas

Reputation: 5103

You're missing the fluent quality of Optionals. Think of them like a Stream:

  @GetMapping(value = "/address/{id}")
  public ResponseEntity<Address> getAddressById(@PathVariable("id") Integer id) {
    return addressService.getAddressById(id)
        .map(ResponseEntity::ok)
        .orElse(new ResponseEntity<Address>(NOT_FOUND));
  }

Upvotes: 7

Ted Hopp
Ted Hopp

Reputation: 234807

Try this:

return address.isPresent()
    ? new ResponseEntity(address.get(), HttpStatus.OK)
    : new ResponseEntity(HttpStatus.NOT_FOUND);

With your current code, you are calling address.get() regardless of whether or not a value is present.

Note that for a more informative NOT_FOUND response (response code 404), you probably should still include a body in the response (which my suggested code does not do). From the HTTP spec (RFC 7231) section on 4xx response codes:

Except when responding to a HEAD request, the server SHOULD send a representation containing an explanation of the error situation, and whether it is a temporary or permanent condition.

According to RFC 2119, the key word "SHOULD" means:

that there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course.

Upvotes: 9

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