This is a sample Spring Boot reactive application with a web filter.
This is also a minimalistic working example for https://stackoverflow.com/questions/52668050/spring-webflux-statuscode-is-null-in-a-webfilter and https://jira.spring.io/browse/SPR-17368
As a conclusion it seems that org.springframework.web.server.WebFilter
requires ResponseEntity in the REST controller return types to correctly retrieve the HTTP response status.
Run with mvn spring-boot:run.
Then connect to various URL and see the HTTP response status from the web filter in the application logs:
- http://localhost:8080/empty1 (returns void): status is null
- http://localhost:8080/empty2 (returns Mono<Void>): status is null
- http://localhost:8080/empty3 (returns ResponseEntity<Void>): status is 200
- http://localhost:8080/empty4 (returns Mono<ResponseEntity<Void>>): status is 200
- http://localhost:8080/hello1 (returns String): status is null
- http://localhost:8080/hello2 (returns Mono<String>): status is null
- http://localhost:8080/hello3 (returns ResponseEntity<String>): status is 200
- http://localhost:8080/hello4 (returns Mono<ResponseEntity<String>>): status is 200
- http://localhost:8080/bean1 (returns MyBean): status is null
- http://localhost:8080/bean2 (returns Mono<MyBean>): status is null
- http://localhost:8080/bean3 (returns ResponseEntity<MyBean>): status is 200
- http://localhost:8080/bean4 (returns Mono<ResponseEntity<MyBean>>): status is 200
- http://localhost:8080/pause1/1000 (returns Mono<String>): status is null
- http://localhost:8080/pause2/1000 (returns Mono<ResponseEntity<String>>): status is 200