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jackson.databind.ObjectMapper upperCasing json Array and Object names

I am trying to use JMSTemplate to publish a JSON message to a topic. This code already existed in one application and I was simply copying it to another as we are trying to consolidate two applications into one. I have found that the code is now sending JSON messages that have the first letter capitalized for the JSONArray and JSONObject field names.
I was using JMS template with a message converter that takes in an object mapper to convert from a POJO to a JSON. The only real difference in my new code is that I am using a newer version of spring boot. I know this would update all of the jackson dependencies so maybe that is why this change has occurred. I ended up trying to set the naming strategy on my object mapper but this doesn't seem to work. I originally did it in my bean definition but in order to see if it was actually working I tried it before I did a convertAndSend, and it did not work. I was still getting uppercase JSON Object and Array names.
public void sendMessage(Object responseToSend) {
objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.LOWER_CAMEL_CASE);// does not seem to make a difference
try {
System.out.println(objectMapper.writeValueAsString(responseToSend));//prints array and object names with the first letter capitolized
} catch (JsonProcessingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
jmsTemplatePublish.convertAndSend("REDACTED",
responseToSend);
}
So, For example, my new application is sending something like.
"Quote":[{"QuoteInformation":{"Inputs":{"exampleField":false,"ExampleWritten":{"dwelling":true}}
where before it was like this
"quote":[{"quoteInformation":{"inputs":{"exampleField":false,"exampleWritten":{"dwelling":true}}

#Kachopsticks did you tried that PropertyNamingStrategy.LOWER_CASE in objectMapper namingStrategy configs instead of using PropertyNamingStrategy.LOWER_CAMEL_CASE.

This bean was the culprit. Had to remove .modulesToInstall(JaxbAnnotationModule.class);
#SuppressWarnings("unchecked")
#Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
return Jackson2ObjectMapperBuilder.json()
.serializationInclusion(JsonInclude.Include.NON_EMPTY)
.defaultViewInclusion(true)
.modulesToInstall(JaxbAnnotationModule.class);
}

How to marshall POJO to JSON using JETTISON?

I have done the marshalling of a JaxB java object to Json using JETTISON. But I can not marshall a simple java object (which has no annotations in it) to Json using JETTISON. I know it is possible to do it by using GSON or MOXy or some other providers.
But I like to get clear "Can we do it using JETTISON?"., If we can, How to do it?
Thanks in Advance.

Don't waste your time, this is simply not what Jettison was designed to do. Conceivably, it would have been possible to instantiate a JSONObject with your POJO and serialize it that way, but there are some issues with its code that make this next to impossible:
It requires passing in the names of the fields that will be included in the JSON.
It can only process public properties of the supplied object.
Not to mention it cannot handle nesting of any kind. Take a look at this lovely code:
Class c = object.getClass();
for (int i = 0; i < names.length; i += 1) {
try {
String name = names[i];
Field field = c.getField(name);
Object value = field.get(object);
this.put(name, value);
} catch (Exception e) {
/* forget about it */
}
}
Yep, thats the code in the constructor JSONObject(Object, String[]). I'm sure you will see the problems with it (raw access to generic objects, can only access public fields, sloppy exception handling). All in all - very bad 'serialization' code.
I know its probably not what you want to hear, but if you want to convert regular Java objects to JSON then you might want to stick with one of the more general-purpose libraries.

JAXB (JSR-222) is configuration by exception and only requires annotations where you need to override the default XML representation (Jettison converts XML StAX events to/from JSON). Instead of #XmlRootElement you can wrap your object in an instance of JAXBElement.
http://blog.bdoughan.com/2012/07/jaxb-no-annotations-required.html

Validate JSON with official JSON for java library

My Question: How can I improve these methods to check that a string is valid json without having to ignore JSONExceptions by using the official JSON for java library?
public boolean isValidJSON(String possibleJson) {
return isJSONObject(possibleJson) || isJSONArray(possibleJson);
}
private boolean isJSONObject(String possibleJson) {
try {
new JSONObject(possibleJson);
return true;
} catch (JSONException ex) {
return false;
}
}
private boolean isJSONArray(String possibleJson) {
try {
new JSONArray(possibleJson);
return true;
} catch (JSONException ex) {
return false;
}
}
I'm pretty sure it's not best practices to depend on exceptions thrown as part of logic in a method. Is there another way to do this?
Note: Remember, I would prefer to not use other libraries to do this. It is a small part of a big project and I don't want to introduce another dependency if I can help it.

If you don't want to use an other library, I think it is the best way to do it. There is no validation function in that lib. If you want to use something else, you can try JSON Tools with the JSONValidator object

From the official JSON Java library Javadocs, it doesn't look like there's any other way. As you don't want to use any other library to do this and you don't want to incur the overhead added by exception handling, a workaround is to check their source code and rewrite a method like isValidJSON yourself (without adding exception handling). A downside of this is you won't get the future modifications to that class/method automatically.
If you're willing to use other libraries, you can check out JSONUtils which has a method like mayBeJSON that returns a boolean.

As per my understanding for javadocs standard there is no specific way that you can check this. except if you handle the exception and validate it with the try catch block. You can use any other libs to validate this. Well here the one that you can use http://json-lib.sourceforge.net/apidocs/net/sf/json/util/JSONUtils.html JavaUtils. there is method name maybeJson(String) that return boolean and validate the json.

Is there a way to create the bean class from a json response

Converting JSON to Java
The above question is with reference to what has been described on the above thread. There are so many API(s) which provide the flexibility to return responses either in XML or JSON. **I would like to know if there is a way to automatically construct the java bean corresponding to a JSON response. **

lets say you get an object like
[
{
"name":"Java 6 Greatest Hits",
"Author":"Jim Bob Jones",
"price":10.25
},
{
"name":"How to raise a goat",
"Author":"Sir Paxton",
"price":55.97
},
{
"name":"Snow - It is cold",
"Author":"Dr. White",
"price":9.99
}
]
And you want a class like
public class Book{
private String author;
private String name;
private Number price
}
with getters and setters
One option is to use a service like JSONGen, which will create that class. You need to use it first, and include the generated code in your project.
Another option could be dynamically generate the class using javassist or CGLib, but that class would be useless unless you use reflection to access its members, so even if it would be a class, it will behave like a really annoying Map. In no way will be better that simple using JSONObject

seems a simple Message Type Entity not meet you requirement ?
if you want convert a json to an existed and known java bean class,
many lib can do so, like
http://json-lib.sourceforge.net/apidocs/net/sf/json/class-use/JSONObject.html
JSONObject.toBean(JSONObject jsonObject, Class beanClass)
Creates a bean from a JSONObject, with a specific target class.
btw, if you are communicating with restful webservice, org.springframework.web.client.RestTemplate will help you get direct bean result
insteadof json.
if class does not exists, you need program with java reflect mechanism.
try use CGLIB ,http://cglib.sourceforge.net/, dynamic create some class like BeanMap. i wrote a simple sample,
but be ware, opearting class byte is hard and you may meet strange trouble with JVM . Strongly not encourage to do so.
public static BeanMap generateBean(JSONObject json) {
BeanGenerator generator = new BeanGenerator();
Iterator keys = json.keys();
while (keys.hasNext()) {
Object key = keys.next();
Object value = json.get(key);
Class keyClass = guessValueClass(value);
generator.addProperty(key.toString(), keyClass);
}
Object result = generator.create();
BeanMap bean = BeanMap.create(result);
keys = json.keys();
while (keys.hasNext()) {
Object key = keys.next();
Object value = json.get(key);
bean.put(key, value);
}
return bean;
}
/**
* TODO fix guess
*/
static Class guessValueClass(Object value) {
try {
Integer.parseInt(value.toString());
return Integer.class;
} catch (NumberFormatException e1) {
}
try {
Double.parseDouble(value.toString());
return Double.class;
} catch (NumberFormatException e1) {
}
return String.class;
}

I believe the main issue here is that the JSON response lacks type information and last time I checked :-) in Java you need to declare the type of a class property. So some heuristics will be needed to infer the type form the value in the JSON response.
For a related question here in SO have a look at: Generate Java class from JSON?

Yes check out http://flexjson.sourceforge.net

If you're wanting to generate Java classes from JSON, perhaps you could try Jackson. It provides a lot of JSON-related functionality, including the ability to generate bytecode from arbitrary JSON. See this blog post for details.

If you're using Jackson (the most popular library there), try
https://bitbucket.org/astav/jsontojava/wiki/Home
Its open source and anyone should be able to contribute.
Summary
A JsonToJava source class file generator that deduces the schema based on supplied sample json data and generates the necessary java data structures.
It encourages teams to think in Json first, before writing actual code.
Features
Can generate classes for an arbitrarily complex hierarchy (recursively)
Can read your existing Java classes and if it can deserialize into those structures, will do so
Will prompt for user input when ambiguous cases exist

Use class name as root key for JSON Jackson serialization

Suppose I have a pojo:
import org.codehaus.jackson.map.*;
public class MyPojo {
int id;
public int getId()
{ return this.id; }
public void setId(int id)
{ this.id = id; }
public static void main(String[] args) throws Exception {
MyPojo mp = new MyPojo();
mp.setId(4);
ObjectMapper mapper = new ObjectMapper();
mapper.configure(SerializationConfig.Feature.WRAP_ROOT_VALUE, true);
System.out.println(mapper.getSerializationConfig().isEnabled(SerializationConfig.Feature.WRAP_ROOT_VALUE));
System.out.println(mapper.writeValueAsString(mp));
}
}
When I serialize using the Jackson ObjectMapper, I just get
true
{"id":4}
but I want
true
{"MyPojo":{"id":4}}
I've searched all over, Jacksons documentation is really unorganized and mostly out of date.

By adding the jackson annotation #JsonTypeInfo in class level you can have the expected output. i just added no-changes in your class.
package com.test.jackson;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.annotation.JsonTypeInfo.As;
import com.fasterxml.jackson.annotation.JsonTypeInfo.Id;
#JsonTypeInfo(include=As.WRAPPER_OBJECT, use=Id.NAME)
public class MyPojo {
// Remain same as you have
}
output:
{
"MyPojo": {
"id": 4
}
}

I'm not using jackson, but searching I found this configuration that seems to be what you want: WRAP_ROOT_VALUE
Feature that can be enabled to make root value (usually JSON Object but can be any type) wrapped within a single property JSON object, where key as the "root name", as determined by annotation introspector (esp. for JAXB that uses #XmlRootElement.name) or fallback (non-qualified class name). Feature is mostly intended for JAXB compatibility.
Default setting is false, meaning root
value is not wrapped.
So that you can configure mapper:
objectMapper.configure(SerializationConfig.Feature.WRAP_ROOT_VALUE, true);
I hope it helps you...

Below is a way to achieve this
Map<String, MyPojo> singletonMap = Collections.singletonMap("mypojo", mp);
System.out.println(mapper.writeValueAsString(singletonMap));
Output
{ "mypojo" : { "id" : 4}}
Here the advantage is that we can give our on name for the root key of json object. By the above code, mypojo will be the root key. This approach will be most useful when we use java script template like Mustache.js for iteration of json objects

To achieve this you need to use the JsonTypeInfo annotation on your class and in particular WRAPPER_OBJECT
#JsonTypeName("foo")
#JsonTypeInfo(include = JsonTypeInfo.As.WRAPPER_OBJECT ,use = JsonTypeInfo.Id.NAME)
public class Bar(){
)

There is also a nice annotation for this:
#JsonRootName(value = "my_pojo")
public class MyPojo{
...
}
will generate:
{
"my_pojo" : {...}
}

How about simplest possible solution; just use a wrapper class like:
class Wrapper {
public MyPojo MyPojo;
}
and wrapping/unwrapping in your code?
Beyond this, it would help to know WHY you would like additional json object entry like this? I know this is done by libs that emulate json via xml api (because of impedance between xml and json, due to conversion from xml to json), but for pure json solutions it is usually not needed.
Is it to allow you do figure out what actual type is?
If so, perhaps you could consider enabled polymorphic type information, to let Jackson handle it automatically? (see 1.5 release notes, entry for PTH, for details).

there is another way i used and that worked for me.
I am working with a third party jar, so i have no control for annotations.
So i had to write through bit of hack.
Override: org.codehaus.jackson.map.ser.BeanSerializerFactory.findBeanProperties(SerializationConfig, BasicBeanDescription)
Add your property as below
List<BeanPropertyWriter> props = super.findBeanProperties(config, beanDesc);
BeanPropertyWriter bpw = null;
try {
Class cc = beanDesc.getType().getRawClass();
Method m = cc.getMethod("getClass", null);
bpw = new BeanPropertyWriter("$className", null, null, m, null,true, null);
} catch (SecurityException e) {
// TODO
} catch (NoSuchMethodException e) {
// TODO
}
props.add(bpw);
return props;
This way i get more control and can do other kind of filters too.

#JsonTypeInfo(include=As.WRAPPER_OBJECT, use=Id.NAME)
This annotation works perfectly, as suggested by Arun Prakash. I was trying to get json in this form:
{"Rowset":{"ROW":{"receiptno":"881604199388936","status":"SUCCESS"}}}
but getting like this:
{"ROW":{"receiptno":"881604199388936","status":"SUCCESS"}}
Now that annotation resolved my problem.

I would be interested in hearing the OP's solution for this. I'm having similar issues where my RESTful web service is serializing objects as either XML or JSON for clients. The Javascript clients need to know the wrapping type so that can parse it. Coupling the type to a URI pattern is not an option.
Thanks.
Edit: I noticed that Spring MappingJacksonJsonMarshaller adds the wrapping class when marshalling, so I stepped through the code in debug and noticed that Spring passes in a HashMap with a single key-value pair such that the key is the wrapping name and the value is the object. So, I extended JacksonJaxbJsonProvider, override the writeTo() method and added the following:
HashMap<String, Object> map = new HashMap<String, Object>();
map.put(value.getClass().getSimpleName(), value);
super.writeTo(map, type, genericType, annotations, mediaType, httpHeaders,entityStream);
It's a bit of a hack, but it works nicely.

use withRootName.
objectMapper.writer().withRootName(MyPojo.class.getName());

I have found through experience that it is a good idea for all JSON to include both the backend type (as a string) and the component type used to render it in the front end (if using something like angular or Vue).
The justification for doing this is so that you can process various types with a single set of code.
In vue, for example, having the name of the UI component in the data allows you, among other things, to have a screen rendering a list of children of different types using only a single tag in the parent template.
<component :is="child.componentType"/>.
For backend systems and web services - I prefer to use a single web service processor class that provides logging, auditing and exception handling for all web services by looking up the appropriate processor class based on the incoming payload. That makes the implementation of all my web services look exactly the same (about 3 lines of code), and I get detailed event logging through the lifecycle of the call without writing any per service code to do so.
Having the type wrapping the JSON makes it self documenting. If all you see are the properties, you have no idea what you are looking at until you find the corresponding end point.
If you want to write data driven software, being able to identify what you are processing is a basic requirement.