Spring Rest Handling Empty Request Body (400 Bad Request)

spring rest Handling empty request body (400 Bad Request)

I solved the issue
(the custom exception handler must extend ResponseEntityExceptionHandler).
My solution follows:

        @ControllerAdvice
        public class RestExceptionHandler extends ResponseEntityExceptionHandler {
    
            @Override
            protected ResponseEntity<Object> handleHttpMessageNotReadable(
                HttpMessageNotReadableException ex, HttpHeaders headers,
                HttpStatus status, WebRequest request) {
                // paste custom hadling here
            }
        }

For 400 Bad Request not getting proper error message

I just updated the bootstrap.yml with server.error.include-message=always. It appears from Spring 2.3.0 the default behavior of Spring has changed. We can refer the following link from more details https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.3-Release-Notes#changes-to-the-default-error-pages-content

Java/Spring > Handle Bad Request response for controller method with @RequestBody when no body is sent in request

The solution was to simply put required = false in RequestBody annotation. After that, I could easily add some logic to throw custom exception and handle it in ControllerAdvice.

@RequestMapping(value = {"register"}, method = RequestMethod.POST, produces = "application/hal+json")
public Resource<User> registerClient(@RequestBody(required = false) User user, HttpServletRequest request){
    logger.debug("addClient() requested from {}; registration of user ({})", getClientIp(request), user);
    if(user == null){
        throw new BadRequestException()
                .setErrorCode(ErrorCode.USER_IS_NULL.toString())
                .setErrorMessage("Wrong body or no body in reqest");
    } (...)

Empty request body gives 400 error

Setting a new byte[0] will not send any content on the request body. If you set spring MVC logs to TRACE you should see a message saying Required request body content is missing as a root cause of your 400 Bad Request

To support your case you should make your @RequestBody optional

@RequestMapping(method=RequestMethod.PUT, value="/items/{itemname}")
public ResponseEntity<?> updateItem(@PathVariable String itemname, @RequestBody(required = false) byte[] data) {
  // code that saves item
}

Spring post method "Required request body is missing"

You have to pass that as JSON in your body, if it's a POST request.

Why do some characters like brackets cause a 400 BAD REQUEST error in a Spring REST endpoint?

You need to encode the URL on the client side.

http://localhost:8083?a=asd[

you should end up with this

http://localhost:8083?a=asd%5B

Clients usually provide a function for URL encoding, please check its documentation. If you are using a client like Postman for testing then you can right click in the address bar and there you have an option to encode the URL.

Some characters like [ are considered allowed but unsafe characters and that's why encoding is needed.

Later edit:

I've tested your code and request and everything works fine. The only change I made was in controller method to return a String instead of a response entity.

@RestController
class Ctrl {
    @GetMapping
    public String getEmails(
            @RequestParam(required = false, name = "a") String a,
            @RequestParam(required = false, name = "b") String b,
            @RequestParam(required = false, name = "c") @DateTimeFormat(iso = DateTimeFormat.ISO.DATE_TIME) LocalDateTime c,
            @RequestParam(required = false, name = "d") @DateTimeFormat(iso = DateTimeFormat.ISO.DATE_TIME) LocalDateTime d,
            @RequestParam(name = "e") Integer e,
            @RequestParam(name = "f") Integer f
    ) {
        return "";
    }
}

curl --location --request GET 'http://localhost:8083?a=&b=%5BHello&c=&d=&e=0&f=1'

You can enable spring debug/trace logging and see what is happening.

400 bad request returned in spring boot even before the request reaches filter

Basically , The problem was Tomcat was not letting the request through.

This behavior was introduced in Tomcat 7.0.76, 8.0.42 and 8.5.12, to conform RFC 7231.

This enforced check can be revert using the property requestTargetAllow in catalina.properties to allow forbiden characters:

tomcat.util.http.parser.HttpParser.requestTargetAllow=|{}

Since I am using embedded tomcat in Intellij and could not edit cataline.properties directly, I added

-Dtomcat.util.http.parser.HttpParser.requestTargetAllow=|{}

to VM Options in Run -> Edit Configuration.

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