I have a spring boot application. trying to send xml payload through postman to a Post request. I get the following exception
java.lang.IllegalStateException: Failed to resolve argument 0 of type 'reactor.core.publisher.Mono' on public reactor.core.publisher.Mono<com.event.gateway.rest.controller.Sir> com.event.gateway.rest.controller.WBController.hello(reactor.core.publisher.Mono<com.event.gateway.rest.controller.Sir>) at org.springframework.web.reactive.result.method.InvocableHandlerMethod.getArgumentError(InvocableHandlerMethod.java:198) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at org.springframework.web.reactive.result.method.InvocableHandlerMethod.resolveArg(InvocableHandlerMethod.java:193) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at org.springframework.web.reactive.result.method.InvocableHandlerMethod.lambda$null$1(InvocableHandlerMethod.java:149) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at java.util.Optional.orElseGet(Optional.java:267) ~[na:1.8.0_91] at org.springframework.web.reactive.result.method.InvocableHandlerMethod.lambda$resolveArguments$2(InvocableHandlerMethod.java:147) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[na:1.8.0_91] at java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948) ~[na:1.8.0_91] at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) ~[na:1.8.0_91] at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) ~[na:1.8.0_91] at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[na:1.8.0_91] at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:1.8.0_91] at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[na:1.8.0_91] at org.springframework.web.reactive.result.method.InvocableHandlerMethod.resolveArguments(InvocableHandlerMethod.java:153) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at org.springframework.web.reactive.result.method.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:117) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at org.springframework.web.reactive.result.method.annotation.RequestMappingHandlerAdapter.lambda$handle$3(RequestMappingHandlerAdapter.java:312) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at reactor.core.publisher.MonoThenMap$MonoThenApplyMain.onNext(MonoThenMap.java:100) [reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:928) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenIgnore$MonoThenIgnoreMain.drain(MonoThenIgnore.java:145) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenIgnore.subscribe(MonoThenIgnore.java:54) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenMap.subscribe(MonoThenMap.java:57) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenMap$MonoThenApplyMain.onNext(MonoThenMap.java:130) [reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:68) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:78) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.innerNext(FluxConcatMap.java:263) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext(FluxConcatMap.java:743) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:119) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:928) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenIgnore$MonoThenAcceptSubscriber.onNext(MonoThenIgnore.java:261) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:1657) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenIgnore$MonoThenAcceptSubscriber.onSubscribe(MonoThenIgnore.java:250) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:59) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenIgnore$MonoThenIgnoreMain.drain(MonoThenIgnore.java:151) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenIgnore.subscribe(MonoThenIgnore.java:54) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoMapFuseable.subscribe(MonoMapFuseable.java:60) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:402) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:203) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:97) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:57) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.FluxConcatMap.subscribe(FluxConcatMap.java:126) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoNext.subscribe(MonoNext.java:41) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoOtherwiseIfEmpty.subscribe(MonoOtherwiseIfEmpty.java:44) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenMap.subscribe(MonoThenMap.java:57) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenMap.subscribe(MonoThenMap.java:57) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoOtherwise.subscribe(MonoOtherwise.java:44) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoOtherwise.subscribe(MonoOtherwise.java:44) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoOtherwise.subscribe(MonoOtherwise.java:44) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenIgnore$MonoThenIgnoreMain.drain(MonoThenIgnore.java:169) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoThenIgnore.subscribe(MonoThenIgnore.java:54) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoOtherwise.subscribe(MonoOtherwise.java:44) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.core.publisher.MonoPeekTerminal.subscribe(MonoPeekTerminal.java:62) ~[reactor-core-3.0.5.RELEASE.jar:3.0.5.RELEASE] at reactor.ipc.netty.channel.ChannelOperations.applyHandler(ChannelOperations.java:405) ~[reactor-netty-0.6.1.RELEASE.jar:0.6.1.RELEASE] at reactor.ipc.netty.http.server.HttpServerOperations.onHandlerStart(HttpServerOperations.java:353) ~[reactor-netty-0.6.1.RELEASE.jar:0.6.1.RELEASE] at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) ~[netty-all-4.1.8.Final.jar:4.1.8.Final] at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:403) ~[netty-all-4.1.8.Final.jar:4.1.8.Final] at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:445) ~[netty-all-4.1.8.Final.jar:4.1.8.Final] at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858) ~[netty-all-4.1.8.Final.jar:4.1.8.Final] at java.lang.Thread.run(Thread.java:745) ~[na:1.8.0_91] Caused by: java.lang.UnsupportedOperationException: null at org.springframework.core.codec.AbstractDecoder.decodeToMono(AbstractDecoder.java:64) ~[spring-core-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at org.springframework.http.codec.DecoderHttpMessageReader.readMono(DecoderHttpMessageReader.java:84) ~[spring-web-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at org.springframework.web.reactive.result.method.annotation.AbstractMessageReaderArgumentResolver.readBody(AbstractMessageReaderArgumentResolver.java:160) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at org.springframework.web.reactive.result.method.annotation.RequestBodyArgumentResolver.resolveArgument(RequestBodyArgumentResolver.java:78) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] at org.springframework.web.reactive.result.method.InvocableHandlerMethod.resolveArg(InvocableHandlerMethod.java:184) ~[spring-webflux-5.0.0.BUILD-SNAPSHOT.jar:5.0.0.BUILD-SNAPSHOT] ... 56 common frames omitted Given below is the POM
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.event.gateway</groupId> <artifactId>endpoint-rest</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>vu-ms-event-gateway</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.0.BUILD-SNAPSHOT</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-webflux</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> <repositories> <repository> <id>spring-snapshots</id> <name>Spring Snapshots</name> <url>https://repo.spring.io/snapshot</url> <snapshots> <enabled>true</enabled> </snapshots> </repository> <repository> <id>spring-milestones</id> <name>Spring Milestones</name> <url>https://repo.spring.io/milestone</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> <pluginRepositories> <pluginRepository> <id>spring-snapshots</id> <name>Spring Snapshots</name> <url>https://repo.spring.io/snapshot</url> <snapshots> <enabled>true</enabled> </snapshots> </pluginRepository> <pluginRepository> <id>spring-milestones</id> <name>Spring Milestones</name> <url>https://repo.spring.io/milestone</url> <snapshots> <enabled>false</enabled> </snapshots> </pluginRepository> </pluginRepositories> </project> Controller
package com.event.gateway.rest.controller; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.ResponseBody; import reactor.core.publisher.Flux; import reactor.core.publisher.Mono; @Controller public class WBController { @RequestMapping(value ="hello", consumes ="application/xml", produces="application/xml", method=RequestMethod.POST) @ResponseBody public Mono <Sir> hello(@RequestBody Mono<Sir> requestBody) { Flux<String> mono = Mono.just("") .concatWith(Mono.from(requestBody) .flatMap(sir -> Flux.fromArray(sir.getLastName().split(""))) .map(String::toUpperCase) .take(4) ); mono.subscribe(System.out::println); return requestBody; } } POJO Class
package com.event.gateway.rest.controller; import java.io.Serializable; import javax.xml.bind.annotation.XmlAccessorType; import javax.xml.bind.annotation.XmlElement; import javax.xml.bind.annotation.XmlRootElement; import com.fasterxml.jackson.annotation.JsonInclude; import javax.xml.bind.annotation.XmlAccessType; @JsonInclude(JsonInclude.Include.NON_NULL) @XmlRootElement(name="sir") @XmlAccessorType(XmlAccessType.FIELD) public class Sir implements Serializable { private static final long serialVersionUID = 1L; @XmlElement(name ="firstName") private String firstName; @XmlElement(name ="lastName") private String lastName; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } } Sample Postman request
POST /hello HTTP/1.1 Host: localhost:8070 Content-Type: application/xml Cache-Control: no-cache Postman-Token: 2132d866-347e-5fcf-de00-2dc8f5f97ac0 <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <sir> <firstName>Jane Doe</firstName> <lastName>Peter</lastName> </sir> I get 500 internal server error as response.
Highly appreciate your help.