Spring boot RestTemplate post giving 400 error

Question

I've written a simple webService in Java 8, on Eclipse Photon, using RestTemplate to post (using postForObject) an object (called patentListWrapper) that wraps a List of objects (called PatentDetails ). I post from a Java client (called MainWsClient ) , then set a value in patentDetails on the server side and read the patentListWrapper object back at the client. It works fine when the server side (program SpringWebServiceHello) uses old Spring MVC 4 technology with only 1 jar file (Spring-web.5.07.RELEASE.jar) following this - serverSideExample ie a web.xml and rest-servlet.xml files controlling the access point. I then wrote another server side program (PndGuidRequestWs) using SpringBoot 2.03 with Spring 5.07 jars, and Maven ,with an identicle @RequestMapping method but no web.xml file and the access point defined in the application.properties file:

server.port=8082
server.servlet.path=/
#spring.mvc.servlet.path=/
#server.servlet.contextPath=/

When I call this new server program using this client - ARC it also works fine but when I call it using the same java client and exactly the same request (accept for a different url obviously). I get a 400 error:

2018-12-18 16:56:53,861 [main] INFO  - Running MainWsClient with name = DS fileType = post3
2018-12-18 16:56:54,101 [main] DEBUG - Created POST request for "http://localhost:8082/guidRequest/xmlList"
2018-12-18 16:56:54,145 [main] DEBUG - Setting request Accept header to [application/xml, text/xml, application/json, application/*+xml, application/*+json]
2018-12-18 16:56:54,152 [main] DEBUG - Writing [com.springservice.client.PatentListWrapper@4ba2ca36] using [org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter@3444d69d]
2018-12-18 16:56:54,384 [main] DEBUG - POST request for "http://localhost:8082/guidRequest/xmlList" resulted in 400 (null); invoking error handler
2018-12-18 16:56:54,387 [main] ERROR - DS1B org.springframework.web.client.HttpClientErrorException: 400 null

The non working ,PndGuidRequestWs, server side has:

@RestController
public class PndController {

@RequestMapping(value = "/guidRequest/xmlList", method = RequestMethod.POST, produces = { "application/xml" } )
public PatentListWrapper guidSearchList(@RequestBody  PatentListWrapper patentListWrapper) {

    for (PatentDetails pd : patentListWrapper.getPatentList())
    {
        pd.setGuid("guidSetOnServer3");
    }

    return patentListWrapper;
  }

}

The working (SpringWebServiceHello) server side is identicle except for :

value = "/service/greeting/xml/post2"

The Java client has:

public void runCode(String name , String fileType)
{

 String url;

 if (fileType.equalsIgnoreCase("post2")) {
        url = "http://localhost:8080/SpringWebServiceHello/service/greeting/xml/post2";
        // This method is identicle to postToPndGuidRequestWs() but this method works fine.
        postToSpringWebServiceHello(url);
    }else if (fileType.equalsIgnoreCase("post3")) {
        url = "http://localhost:8082/guidRequest/xmlList";      
        // This method gives 404 error          
        postToPndGuidRequestWs(url);
    }   
}

private void postToPndGuidRequestWs(String url) 
{

    PatentListWrapper patentListWrapper = new PatentListWrapper();
    PatentDetails pd = new PatentDetails("CN","108552082","A","00000000",12345,"guidIn");

    List<PatentDetails> patentList = new ArrayList<PatentDetails>();
    patentList.add(pd);
    patentListWrapper.setPatentList(patentList);

    RestTemplate restTemplate = new RestTemplate();

    /* HttpHeaders headers = new HttpHeaders();
    headers.add("header_name", "header_value");
    headers.setContentType(MediaType.APPLICATION_XML);
    HttpEntity<PatentListWrapper> request = new HttpEntity<PatentListWrapper>(patentListWrapper, headers); */

    /*List<HttpMessageConverter<?>> messageConverters = new ArrayList<HttpMessageConverter<?>>();
    Jaxb2RootElementHttpMessageConverter jaxbMessageConverter = new Jaxb2RootElementHttpMessageConverter();
    List<MediaType> mediaTypes = new ArrayList<MediaType>();
    mediaTypes.add(MediaType.APPLICATION_XML);
    jaxbMessageConverter.setSupportedMediaTypes(mediaTypes);
    messageConverters.add(jaxbMessageConverter);
    restTemplate.setMessageConverters(messageConverters);*/

    /* headers = new HttpHeaders();
    headers.setAccept(Collections.singletonList(MediaType.APPLICATION_XML));
    HttpEntity<String> entity = new HttpEntity<>("parameters", headers);*/


    try {
        patentListWrapper = restTemplate.postForObject(
                url,
                patentListWrapper,
                PatentListWrapper.class);


        logger.debug("DS1A employee obj returned. guid = " +  patentListWrapper.getPatentList().get(0).getGuid());
    }catch(Exception e) {
        logger.error("DS1B " + e);      
    }   
}

}

ie fileType="post2" calls SpringWebServiceHello, fileType="post3" calls PndGuidRequestWs. As you can see i've tried several commented out solutions but nothing works. Since the only real difference between the 2 server side programs is that none working one uses Spring boot and the working one doesn't the problem must be in the SpringBoot setup ie directory structure, application.properties or pom.xml. My pom.xml has:

<?xml version="1.0" encoding="UTF-8"?>

http://maven.apache.org/xsd/maven-4.0.0.xsd"> 4.0.0

<groupId>com.clarivate</groupId>
<artifactId>pndguidrequestws</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>

<name>pndGuidRequestWs</name>
<description>Guid request webService</description>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.3.RELEASE</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>
    <start-class>com.clarivate.pndguidrequestws.PndGuidRequestWsApplication</start-class>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

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

    <dependency>
        <groupId>com.oracle</groupId>
        <artifactId>ojdbc6</artifactId>
        <version>11.2.0.1.0</version> 
      <!--    <scope>provided</scope> --> <!-- DS insert for unix -->
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
        <exclusions>
            <exclusion>
                <groupId>org.apache.tomcat</groupId>
                <artifactId>tomcat-jdbc</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <!-- Implementing XML Representation for Spring Boot Services -->
    <dependency>
      <groupId>com.fasterxml.jackson.dataformat</groupId>
      <artifactId>jackson-dataformat-xml</artifactId>
    </dependency>

    <!-- httpcomponents jars are Required by PndGuidGenerator -->
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpcore</artifactId>
    </dependency>

    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
    </dependency>
</dependencies>


<build>
    <finalName>PndGuidRequestWs</finalName>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId> 
            <configuration>
                  <executable>true</executable>
            </configuration> 
        </plugin>
    </plugins>      
</build>
</project>

The PatentListWrapper class is:

package com.clarivate.pndguidrequestws.model;

import java.util.List;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class PatentListWrapper {

private List<PatentDetails> patentList;

public PatentListWrapper() {}

public List<PatentDetails> getPatentList() {
    return patentList;
}

public void setPatentList(List<PatentDetails> patentList) {
    this.patentList = patentList;
}   

}

Any suggestions most welcome.

EDIT: To simplify the object I created PatentListWrapper2 with just 1 string member:

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class PatentListWrapper2 {

private String name;

public  PatentListWrapper2() {}

public  PatentListWrapper2(String name) {
    this.name = name;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

}

I can again successfully send this xml using the ARC client:

<patentListWrapper2>
   <name>DSDS</name>
</patentListWrapper2>

with contentType="application/xml" but when I try to send patentListWrapper2 from java I get an unmarshalling error:

 2018-12-20 09:17:13,931 [main] INFO  - Running MainWsClient with name = DS fileType = post4
2018-12-20 09:17:14,166 [main] DEBUG - Created POST request for "http://localhost:8082/guidRequest/xmlList2"
2018-12-20 09:17:14,200 [main] DEBUG - Setting request Accept header to [application/xml, text/xml, application/json, application/*+xml, application/*+json]
2018-12-20 09:17:14,206 [main] DEBUG - Writing [com.springservice.client.PatentListWrapper2@517cd4b] using [org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter@6cc7b4de]
2018-12-20 09:17:14,246 [main] DEBUG - POST request for "http://localhost:8082/guidRequest/xmlList2" resulted in 200 (null)
2018-12-20 09:17:14,248 [main] DEBUG - Reading [com.springservice.client.PatentListWrapper2] as "application/xml;charset=UTF-8" using [org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter@6cc7b4de]
2018-12-20 09:17:14,255 [main] ERROR - DS2B org.springframework.web.client.RestClientException: Error while extracting response for type [class com.springservice.client.PatentListWrapper2] and content type [application/xml;charset=UTF-8]; nested exception is org.springframework.http.converter.HttpMessageNotReadableException: Could not unmarshal to [class com.springservice.client.PatentListWrapper2]: unexpected element (uri:"", local:"PatentListWrapper2"). Expected elements are <{}patentListWrapper2>; nested exception is javax.xml.bind.UnmarshalException: unexpected element (uri:"", local:"PatentListWrapper2"). Expected elements are <{}patentListWrapper2>

EDIT2 I ran pndGuidRequestWs on Eclipse Tomcat , instead of - Run As -> Spring Boot App. The server log is below:

2018-12-20 11:15:45.655  WARN 236 --- [nio-8080-exec-6] .w.s.m.s.DefaultHandlerExceptionResolver : Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot construct instance of `com.clarivate.pndguidrequestws.model.PatentDetails` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('CN'); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `com.clarivate.pndguidrequestws.model.PatentDetails` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('CN') at [Source: (PushbackInputStream); line: 1, column: 98] (through reference chain: com.clarivate.pndguidrequestws.model.PatentListWrapper["patentList"]->java.util.ArrayList[0])         

Answer 1

PatentListWrapper is a complex object, not a piece of xml , so the answer is to remove all references to xml ie

1. Remove @XmlRootElement(name="PatentListWrapper") from PatentListWrapper.
2. Add jackson-*.jar(s) into the classpath to do the message converting

3. Change the server side @RequestMapping from :

   @RequestMapping(value = "/xmlList", method = RequestMethod.POST , consumes = { "application/xml" }, produces = { "application/xml" }) 
   

to

@RequestMapping(value = "/xmlList", method = RequestMethod.POST )

This means that the ARC client now returns JSON (as it's the default return type), even when I send xml, but that's not important as it's just a test tool.

So, when posting objects with RestTemplate in Spring 2, no contentType settings or additional messageConverters are required on the client side , just:

RestTemplate restTemplate = new RestTemplate();
MyObject myObjectReturn = restTemplate.postForObject(url,myObject,MyObject.class);

and on the server side:

@RestController
@RequestMapping(value = "/endPoint", method = RequestMethod.POST)
public MyObject anyMethodName(@RequestBody  MyObject myObject) {
     //Do stuff to myObject
     return myObject;
}

Answer 2

Can you test with :

try {
        HttpHeaders headers = new HttpHeaders();
        //headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        //headers.setContentType((MediaType.APPLICATION_JSON));
        // I comment the code abouve because you did not specify a consumes whitch  defines the media types that the methods of 
        //a resource class or MessageBodyReader can accept. If not specified, a container will assume that any media type is acceptable.
        HttpEntity<PatentListWrapper> request = new HttpEntity<>(patentListWrapper, headers);
        PatentListWrapper patentListWrapperResult =  = restTemplate.exchange(url, HttpMethod.POST, request,PatentListWrapper.class);


        logger.debug("DS1A employee obj returned. guid = " +  patentListWrapper.getPatentList().get(0).getGuid());
    }catch(Exception e) {
        logger.error("DS1B " + e);      
    }