“Could not find acceptable representation” using spring-boot-starter-web

I am trying to use spring-boot-starter-web to create a rest service serving up JSON representations of Java objects. From what I understand this boot-starter-web jar is supposed to handle the conversion to JSON through Jackson automatically but I am instead getting this error.

{ 
  "timestamp": 1423693929568,
  "status": 406,
  "error": "Not Acceptable",
  "exception": "org.springframework.web.HttpMediaTypeNotAcceptableException",
  "message": "Could not find acceptable representation"
}

My Controller is this…

@RestController
@RequestMapping(value = "/media")
public class MediaController {
    @RequestMapping(value = "/test", method = RequestMethod.POST)
    public @ResponseBody UploadResult test(@RequestParam(value="data") final String data) {
      String value = "hello, test with data [" + data + "]"; 
      return new UploadResult(value);
    }

    @RequestMapping(value = "/test2", method = RequestMethod.POST)
    public int test2() {
        return 42;
    }

    @RequestMapping(value = "/test3", method = RequestMethod.POST)
    public String test3(@RequestParam(value="data") final String data) {
        String value = "hello, test with data [" + data + "]"; 
        UploadResult upload = new UploadResult(value);
        return upload.value;
    }


    public static class UploadResult {
        private String value;
        public UploadResult(final String value)
        {
            this.value = value;
        }
    }
}

My pom.xml has…

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>1.2.1.RELEASE</version>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <version>1.2.1.RELEASE</version>
    <scope>provided</scope>
</dependency>

mvn dependency:tree shows that spring-boot-starter-web does indeed depend on the jackson2.4 databind and thus should be on the classpath…

[INFO] +- org.springframework.boot:spring-boot-starter-web:jar:1.2.1.RELEASE:compile
[INFO] |  +- org.springframework.boot:spring-boot-starter:jar:1.2.1.RELEASE:compile
[INFO] |  |  +- org.springframework.boot:spring-boot:jar:1.2.1.RELEASE:compile
[INFO] |  |  +- org.springframework.boot:spring-boot-autoconfigure:jar:1.2.1.RELEASE:compile
[INFO] |  |  +- org.springframework.boot:spring-boot-starter-logging:jar:1.2.1.RELEASE:compile
[INFO] |  |  |  +- org.slf4j:jul-to-slf4j:jar:1.7.8:compile
[INFO] |  |  |  - org.slf4j:log4j-over-slf4j:jar:1.7.8:compile
[INFO] |  |  - org.yaml:snakeyaml:jar:1.14:runtime
[INFO] |  +- com.fasterxml.jackson.core:jackson-databind:jar:2.4.4:compile
[INFO] |  |  +- com.fasterxml.jackson.core:jackson-annotations:jar:2.4.0:compile
[INFO] |  |  - com.fasterxml.jackson.core:jackson-core:jar:2.4.4:compile
[INFO] |  +- org.hibernate:hibernate-validator:jar:5.1.3.Final:compile
[INFO] |  |  +- javax.validation:validation-api:jar:1.1.0.Final:compile
[INFO] |  |  +- org.jboss.logging:jboss-logging:jar:3.1.3.GA:compile
[INFO] |  |  - com.fasterxml:classmate:jar:1.0.0:compile
[INFO] |  +- org.springframework:spring-web:jar:4.1.4.RELEASE:compile
[INFO] |  |  +- org.springframework:spring-aop:jar:4.1.4.RELEASE:compile
[INFO] |  |  |  - aopalliance:aopalliance:jar:1.0:compile
[INFO] |  |  +- org.springframework:spring-beans:jar:4.1.4.RELEASE:compile
[INFO] |  |  - org.springframework:spring-context:jar:4.1.4.RELEASE:compile
[INFO] |  - org.springframework:spring-webmvc:jar:4.1.4.RELEASE:compile
[INFO] |     - org.springframework:spring-expression:jar:4.1.4.RELEASE:compile

… yet calling the test service gives the error mentioned above. test2 and test3 work fine proving that it must just be the attempted conversion to JSON that is failing? Am I missing some configuration problem or annotations? From all the examples I can find, annotating the class for basic Jackson JSON conversion is no longer necessary.

Any help greatly appreciated.

Answer

You have no public getters for your UpdateResult, for example :

public static class UploadResult {
    private String value;
    public UploadResult(final String value)
    {
        this.value = value;
    }

    public String getValue() {
       return this.value;
    }
}

I believe by default auto discovery is on and will try to discover your getters. You can disable it with @JsonAutoDetect(getterVisibility=Visibility.NONE), and in your example will result in [].

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Answer