Why Optional and @PathVariable combination is not supported by Spring/java?
Question
I would like to make an api that could accept two Path variables and one of them could be optional. In this article they said that we can achieve this by using Optional, but this is not working.
here is my Controller
@GetMapping("/users/{dateDu}/{dateAu}")
public ResponseEntity<List<User>> getAllUsersByDate(
@PathVariable LocalDate dateDu,
@PathVariable(required = false) Optional<LocalDate> dateAu,
@org.springdoc.api.annotations.ParameterObject Pageable pageable
) {
if(dateAu.isEmpty()){
dateAu = Optional.of(LocalDate.now());
}
Page<User> page = userRepository.getUsersByDate(dateDu, dateAu.get(), pageable);
HttpHeaders headers = PaginationUtil.generatePaginationHttpHeaders(ServletUriComponentsBuilder.fromCurrentRequest(), page);
return ResponseEntity.ok().headers(headers).body(page.getContent());
}
in this image of swagger the two parameters are required even if the second one has Optional
Since I generated my spring boot app with JHipster, on postman when I don't give a the value of the Optional parameter. I got this error
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I would appreciate if any one could help me to understand why this is happening and/or how I could solve it. Thank you in advance.
3 answers
solution1
1 ACCPTED 2022-05-27 19:35:27
This is a composite question. I found some issues in your question.
First, you should change your path to
@GetMapping(value = {"/users/{dateDu}", "/users/{dateDu}/{dateAu}"})
Otherwise you will get 404 error if you don't provide dateAu in your request.
Second, you should add @DateTimeFormat(iso = DateTimeFormat.ISO.DATE) to your parameters to tell Spring how to convert String to LocalDate. Otherwise you will get a Bad Request with error message.
Failed to convert value of type 'java.lang.String' to required type 'java.time.LocalDate'
You didn't notice this issue because Swagger have already handled it for you, I guess.
I try to fix your code:
@GetMapping(value = {"/users/{dateDu}", "/users/{dateDu}/{dateAu}"})
public ResponseEntity<List<User>> getAllUsersByDate(
@PathVariable @DateTimeFormat(iso = DateTimeFormat.ISO.DATE) LocalDate dateDu,
@PathVariable(required = false) @DateTimeFormat(iso = DateTimeFormat.ISO.DATE) Optional<LocalDate> dateAu,
@org.springdoc.api.annotations.ParameterObject Pageable pageable) {
if (dateAu.isEmpty()) {
dateAu = Optional.of(LocalDate.now());
}
Page<User> page = userRepository.getUsersByDate(dateDu, dateAu.get(), pageable);
HttpHeaders headers = PaginationUtil
.generatePaginationHttpHeaders(ServletUriComponentsBuilder.fromCurrentRequest(), page);
return ResponseEntity.ok().headers(headers).body(page.getContent());
}
I think it should be work if you use postman to test.
Third, according to this post , all of @PathVariable MUST be required in Swagger. It means your question is nothing to do with combination of @PathVariable and Optional in Java. It's a spec/limitation of Swagger. Thus, if you really want to use Swagger to test your API, you have 2 choices:
- Split it to 2 endpoints, as @tucuxi said.
- Use QueryString style instead.
Last, it seems like you probably don't need an Optional . Optional is designed to be used as a return type in most case. But this is a controversial design issue. So, if you really want to use Optional , you can follow the best practice described by this excellent article
solution2
0 2022-05-27 19:18:52
Maybe try adding the 2 paths to the @GetMapping?
@GetMapping("/users/{dateDu}", "/users/{dateDu}/{dateAu}")
solution3
0 2022-05-27 19:44:53
不确定这是否能解决您的问题，但您可能应该删除参数注释中的错误标志： @PathVariable Optional<LocalDate> dateAu并添加两个路径： @GetMapping(value = {"/users/{dateDu}", "/users/{dateDu}/{dateAu}"}) 。
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