Spring MVC : The request sent by the client was syntactically incorrect

Question

When sending JSON requests to the server, I\'m often greeted by this message:

The request sent by the client was syntactically incorrect ().

Answer 1

I was facing the same error since couple of days, finally enabled the debug logging as mentioned by @Farm and was able to see the cause of this issue. I had a Person Object being posted in json from jsp to spring controller as shown below:-

@RequestMapping(value = "/get", method = RequestMethod.POST)
public @ResponseBody
Person getPerson(@RequestBody Person person) {
    // System.out.println("inside get::::::::");
    System.out.println("city:=" + person.getResidenceAddress().getCity()+" "
            + "name:= " + person.getFullName().getFirstName());
    // Person prsn = personService.getPerson(person);

    /*
     * Person prsn = new Person(); prsn.setId(1); ResponseDecorator rd = new
     * ResponseDecorator(prsn, true);
     */return person;
}
// Person Object
class Person{
private Name fullName;
private Address residenceAddress;
private Address mailingAddress;
private Gender gender;
private MaritalStatus maritalStatus;
private Integer creditRating;

}

 //Address Object
public class Address {
private String streetNo;
private String streetName;
private String suburb;
private String city;
private String state;
private String country;
private Integer pinCode;
private AddressType addressType;
}


json post from jsp:-
//create JSON 
var json = {
"id": id,
        "fullName":{"firstName":firstName,"middleName":middleName,"surName":     surName},
 "residenceAddress":{ "streetNo": streetNo,
                      "streetName": streetName,
                      "suburb": suburb,
                      "city": city,
                      "state": state,   
                      "country": country,
                      "pinCode": pincode
                      }
        };

 var dataString = JSON.stringify(json);
//alert(dataString);


$.ajax({
    headers: {
        Accept : "text/plain; charset=utf-8, application/json"},
    url: "/myservice/get", 
    type: 'POST', 
    dataType: 'json', 
    //data : "{     }",
    data: dataString, 
    contentType: 'application/json',
    mimeType: 'application/json',
    success: function(data) { 
        alert(data);
    },
    error:function(data,status,er) { 
        alert("error: "+data+" status: "+status+" er:"+er);
    }
}); 

The error on submit was 400 Bad request and there was no other clue as to why it was failing. On enabling the debug mode on the server, I could see the below error stack trace:-

**00:53:42,294 DEBUG RequestResponseBodyMethodProcessor:117 - Reading [com.foo.assignment.model.Person] as "application/json" using [org.springframework.http.converter.json.MappingJacksonHttpMessageConverter@1813fb]
00:53:42,310 DEBUG ServletInvocableHandlerMethod:159 - Error resolving argument [0] [type=com.foo.assignment.model.Person]
HandlerMethod details: 
Controller [com.foo.assignment.controller.PersonController]
Method [public com.foo.assignment.model.Person com.foo.assignment.controller.PersonController.getPerson(com.foo.assignment.model.Person)]
org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: No suitable constructor found for type [simple type, class com.foo.assignment.model.Address]: can not instantiate from JSON object (need to add/enable type information?)
 at [Source: org.apache.catalina.connector.CoyoteInputStream@f264df; line: 1, column: 98] (through reference chain: com.foo.assignment.model.Person["residenceAddress"]); nested exception is org.codehaus.jackson.map.JsonMappingException: No suitable constructor found for type [simple type, class com.foo.assignment.model.Address]: can not instantiate from JSON object (need to add/enable type information?)
 at [Source: org.apache.catalina.connector.CoyoteInputStream@f264df; line: 1, column: 98] (through reference chain: com.foo.assignment.model.Person["residenceAddress"])
    at org.springframework.http.converter.json.MappingJacksonHttpMessageConverter.readInternal(MappingJacksonHttpMessageConverter.java:127)
    at org.springframework.http.converter.AbstractHttpMessageConverter.read(AbstractHttpMessageConverter.java:153)
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:120)
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:91)
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:71)
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:74)
    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:155)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:117)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:900)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:722)
Caused by: org.codehaus.jackson.map.JsonMappingException: No suitable constructor found for type [simple type, class com.foo.assignment.model.Address]: can not instantiate from JSON object (need to add/enable type information?)
 at [Source: org.apache.catalina.connector.CoyoteInputStream@f264df; line: 1, column: 98] (through reference chain: com.foo.assignment.model.Person["residenceAddress"])
    at org.codehaus.jackson.map.JsonMappingException.from(JsonMappingException.java:163)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObjectUsingNonDefault(BeanDeserializer.java:746)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:683)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
    at org.codehaus.jackson.map.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:299)
    at org.codehaus.jackson.map.deser.SettableBeanProperty$MethodProperty.deserializeAndSet(SettableBeanProperty.java:414)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:697)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
    at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2732)
    at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1923)
    at org.springframework.http.converter.json.MappingJacksonHttpMessageConverter.readInternal(MappingJacksonHttpMessageConverter.java:124)
    ... 37 more
00:53:42,310 DEBUG ExceptionHandlerException**

Adding a default constructor in the Address object solved the error. And using Google add-on Postman(plugin https://chrome.google.com/webstore/detail/postman/fhbjgbiflinjbdggehcddcbncffffdomop?hl=en) really helped in testing my changes pretty fast.