Could not write content: No serializer found for class org.springframework.context.expression.StandardBeanExpressionResolver

Question

I am using a simple POJO as a session bean and using the same POJO as a json response for my $.ajax calls.

POJO

    public class TransportPacket implements Serializable {
    private static final long serialVersionUID = 1L;
    private String name;
    private String fieldName , fieldValue, query, error, buttonName, formName, actionName;
    private List<String> results = new ArrayList<String>();
    private boolean redirect = false;
    private Object[][] data;
    private Map<String, String> mapOfFieldsWithValues;
    private String[] fieldsToBeShown;
    private List<String> extraFieldsChosen = new ArrayList<String>();

public String getFormName() {
    return formName;
}

public void setFormName(String formName) {
    this.formName = formName;
}

public String getActionName() {
    return actionName;
}

public void setActionName(String actionName) {
    this.actionName = actionName;
}

@JsonIgnore
public void initialize() {
    fieldName = "";
    fieldValue = "";
    query = "";
    error = "";
    buttonName = "";
    if(this.getMapOfFieldsWithValues() != null) {
        this.getMapOfFieldsWithValues().clear();
    }
    this.getExtraFieldsChosen().clear();
    this.fieldsToBeShown = null;
}

@JsonIgnore
public void clear() {
    this.initialize();
}

public String getButtonName() {
    return buttonName;
}

public void setButtonName(String buttonName) {
    this.buttonName = buttonName;
}

public String getError() {
    return error;
}

public void setError(String error) {
    this.error = error;
}

public String getQuery() {
    return query;
}

public void setQuery(String query) {
    this.query = query;
}

public String getFieldName() {
    return fieldName;
}

public void setFieldName(String fieldName) {
    this.fieldName = fieldName;
}

public String getFieldValue() {
    return fieldValue;
}

public void setFieldValue(String fieldValue) {
    this.fieldValue = fieldValue;
}

public List<String> getResults() {
    return results;
}

public void setResults(List<String> results) {
    this.results = results;
}

public boolean isRedirect() {
    return redirect;
}

public void setRedirect(boolean redirect) {
    this.redirect = redirect;
}

public Object[][] getData() {
    return data;
}

public void setData(Object[][] data) {
    this.data = data;
}

public Map<String, String> getMapOfFieldsWithValues() {
    return mapOfFieldsWithValues;
}

public void setMapOfFieldsWithValues(Map<String, String> mapOfFieldsWithValues) {
    this.mapOfFieldsWithValues = mapOfFieldsWithValues;
}

public String[] getFieldsToBeShown() {
    return fieldsToBeShown;
}

public void setFieldsToBeShown(String[] fieldsToBeShown) {
    if(this.fieldsToBeShown != null) {
        List<String> existingFields = Arrays.asList(this.fieldsToBeShown);
        this.getExtraFieldsChosen().clear();
        for(String field : fieldsToBeShown) {
            if(!existingFields.contains(field)) {
                this.getExtraFieldsChosen().add(field);
            }
        }
    } else {
        this.getExtraFieldsChosen().addAll(Arrays.asList(fieldsToBeShown));
    }
    this.fieldsToBeShown = fieldsToBeShown;
}

public List<String> getExtraFieldsChosen() {
    return extraFieldsChosen;
}

public void setExtraFieldsChosen(List<String> extraFieldsChosen) {
    this.extraFieldsChosen = extraFieldsChosen;
}

public String getName() {
    return name;
}

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

In my ApplicationContext.xml I have added the following :

<bean id="packet" class="com.visa.vdps.dbmsrep.data.TransportPacket" scope="session"> <aop:scoped-proxy/> </bean>

and

<mvc:annotation-driven> <mvc:message-converters register-defaults="true"> <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" /> </mvc:message-converters> </mvc:annotation-driven>

Now I am Autowiring the bean using @Autowired in one of my Controllers. In the same controller I am using the following method :

     @RequestMapping(value="/SendFieldValueBack.htm", method=RequestMethod.POST)
     public @ResponseBody TransportPacket validateField(HttpServletRequest request, HttpServletResponse response) {

        String fieldName = request.getParameter("fieldName");
        String fieldValue = request.getParameter("fieldValue");

        // POJO
        packet.setFieldName(fieldName);
        packet.setFieldValue(fieldValue);
        packet.setMapOfFieldsWithValues(this.mapOfFieldsWithValues);
        this.addingActionPerformed(true);
        request.getSession().setAttribute("packet", packet);
        return this.getPacket();
    }

This method is called from the following ajax method :

    $(document).ready(
    $.ajax({
          url: "SendFieldValueBack.htm",
          data: {"fieldName":fieldName, "fieldValue":fieldValue},
          dataType: "json",
          type: "POST",
          cache: false,
          success: function(data, textStatus, jQxhr){
                  alert("success");
              evaluateDataFromController(data);
          },
          error: function(xhr, ajaxOptions, thrownError){
               // code here
              alert("Error from SendFieldValueBack.htm");
              writeToConsole(thrownError);
          }
    }));

I get the error alert "Error from SendFieldValueBack.htm" and the following stacktrace :

13963 [http-bio-8080-exec-6] WARN org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver - Failed to write HTTP message: org.springframework.http.converter.HttpMessageNotWritableException: Could not write content: No serializer found for class org.springframework.context.expression.StandardBeanExpressionResolver and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.visa.vdps.dbmsrep.data.TransportPacket$$EnhancerBySpringCGLIB$$be504698["targetSource"]->org.springframework.aop.target.SimpleBeanTargetSource["beanFactory"]->org.springframework.beans.factory.support.DefaultListableBeanFactory["beanExpressionResolver"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.springframework.context.expression.StandardBeanExpressionResolver and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.visa.vdps.dbmsrep.data.TransportPacket$$EnhancerBySpringCGLIB$$be504698["targetSource"]->org.springframework.aop.target.SimpleBeanTargetSource["beanFactory"]->org.springframework.beans.factory.support.DefaultListableBeanFactory["beanExpressionResolver"]) 13963 [http-bio-8080-exec-6] WARN org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver - Handler execution resulted in exception: Could not write content: No serializer found for class org.springframework.context.expression.StandardBeanExpressionResolver and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.visa.vdps.dbmsrep.data.TransportPacket$$EnhancerBySpringCGLIB$$be504698["targetSource"]->org.springframework.aop.target.SimpleBeanTargetSource["beanFactory"]->org.springframework.beans.factory.support.DefaultListableBeanFactory["beanExpressionResolver"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.springframework.context.expression.StandardBeanExpressionResolver and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.visa.vdps.dbmsrep.data.TransportPacket$$EnhancerBySpringCGLIB$$be504698["targetSource"]->org.springframework.aop.target.SimpleBeanTargetSource["beanFactory"]->org.springframework.beans.factory.support.DefaultListableBeanFactory["beanExpressionResolver"])

I am using Jackson2HttpMessageConverter. Could someone please help me ?

Thanks in advance.

(I am posting a question for the first time here. So please let me know if I have not done this in a proper way)

Answer 1

I know it's been years, but I stumbled upon this because I had the same issue. The TransportPacket object created by Spring is a proxy, so it has lots of other fields and methods on it that aren't defined by you. A good strategy here would be to create a new class, say, TransportPacketDTO, and transfer properties from TransportPacket to TransportPacketDTO, and this is what you would return from your @RequestMapping method.