Using Spring Boot, I have implemented a RestController like so:
@RestController
@RequestMapping("/api/v1/student/img")
@CrossOrigin("*")
public class ProfilePictureController {
@GetMapping( "/{studentId}")
public void getProfilePicture(@PathVariable(required = false) Long studentId, HttpServletResponse response) throws IOException {
Optional<ProfilePicture> profilePicture;
if (studentId != null) {
profilePicture= studentService.getProfilePictureByStudentId(studentId);
} else {
profilePicture= studentService.getProfilePicture(1L);
}
if (profilePicture.isPresent()) {
ServletOutputStream outputStream = response.getOutputStream();
outputStream.write(profilePicture.get().getImage());
outputStream.close();
}
}
My ProfilePicture-class contains a variable "image", which is of type byte[]. I am trying to retrieve this variable.
Anyways, the issue is that my controller does not seem to treat my PathVariable as optional. If I use the fetch-API to send a GET request with the following URL:
const url = "http://localhost:8080/api/v1/student/img/",
I am getting an error:
'java.lang.String' to required type 'java.lang.Long'; nested exception is java.lang.NumberFormatException: For input string: "img".
Does anyone know what might be the issue?
You only define the resource /api/v1/student/img/{studentId} but NOT the resource /api/v1/student/img/.
So if you just call /api/v1/student/img/ as you mentioned , it should return you 404 Not Found but not the following error that you mentioned :
'java.lang.String' to required type 'java.lang.Long'; nested exception is java.lang.NumberFormatException: For input string: "img".
I believe you are actually calling /api/v1/student/img/img instead. As img is not a Long and hence the error.
If you just want to call /api/v1/student/img/ without any studentId , you should define another resource for it (see below). Technically , they are different resources.
@RestController
@RequestMapping("/api/v1/student/img")
@CrossOrigin("*")
public class ProfilePictureController {
@GetMapping( "/{studentId}")
public void getProfilePicture(@PathVariable(required = false) Long studentId, HttpServletResponse response) throws IOException {
}
@GetMapping
public void getProfilePicture(HttpServletResponse response) throws IOException {
}
}
Or defining two resource paths on the @GetMapping with Optional on the paramater :
@RestController
@RequestMapping("/api/v1/student/img")
@CrossOrigin("*")
public class ProfilePictureController {
@GetMapping( {"/", "/{studentId}"})
public void getProfilePicture(@PathVariable(required = false) Optional<Long> studentId, HttpServletResponse response) throws IOException {
}
}
/api/v1/student/img/ doesn't match /api/v1/student/img/{studentId}. So your mapping will not work.
In addition to other anwser, In my opinion the best way to handle this is to add another mapping to the same method.
@GetMapping( {"/","/{studentId}"})
public void getProfilePicture(@PathVariable(required = false) Long studentId, HttpServletResponse response) throws
IOException {
}
Find out more here https://medium.com/latesttechupdates/define-spring-optional-path-variables-1188fadfebde
You can't have optional path variables, but you can have two controller methods which call the same service code: but
If you are using Java 8 and above and Spring 4.1 and above you can use java.util.Optional which is supported in @RequestParam, @PathVariable, @RequestHeader and @MatrixVariable in Spring MVC
@RestController
@RequestMapping("/api/v1/student/img")
@CrossOrigin("*")
public class ProfilePictureController {
@GetMapping( "/{studentId}")
public void getProfilePicture(@PathVariable Optional<Long> type studentId, HttpServletResponse response) throws IOException {
Optional<ProfilePicture> profilePicture;
if (studentId.isPresent()) {
profilePicture= studentService.getProfilePictureByStudentId(studentId.get());
} else {
profilePicture= studentService.getProfilePicture(1L);
}
if (profilePicture.isPresent()) {
ServletOutputStream outputStream = response.getOutputStream();
outputStream.write(profilePicture.get().getImage());
outputStream.close();
}
}