spring-boot json root name - json

Question

I'm using spring-boot 1.3.3 and trying to figure out how to have root names on JSON serialization. For example, I would like...
{ stores: [
{
id: 1,
name: "Store1"
},
{
id: 2,
name: "Store2"
}]
}
but instead I am getting
[
{
id: 1,
name: "Store1"
},
{
id: 2,
name: "Store2"
}
]
I've been looking at #JsonRootName and customizing the Jackson2ObjectMapperBuilder config but to no avail. In grails, this is pretty simple with Json Views and I was trying also to see how that translated directly to spring-boot but still can't seem to figure it out.
I realize this is similar to this question but I feel like in the context of Spring (boot) it might be applied differently and would like to know how.

Answer 1

SpringBoot use Jackson as json tool, so this will work well:
#JsonTypeName("stores")
#JsonTypeInfo(include = JsonTypeInfo.As.WRAPPER_OBJECT, use = JsonTypeInfo.Id.NAME)
public class stores {
...
}

Answer 2

Solution 1: Jackson JsonRootName
I've been looking at #JsonRootName and
customizing the Jackson2ObjectMapperBuilder config but to no avail
What are your errors with #JsonRootName and the Jackson2ObjectMapperBuilder?
This works in my Spring Boot (1.3.3) implementation:
Jackson configuration Bean
#Configuration
public class JacksonConfig {
#Bean
public Jackson2ObjectMapperBuilder jacksonBuilder() {
Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
builder.featuresToEnable(SerializationFeature.WRAP_ROOT_VALUE);
// enables wrapping for root elements
return builder;
}
}
Reference: Spring Documentation - Customizing the Jackson ObjectMapper
Add #JsonRootElement to your response entity
#JsonRootName(value = "lot")
public class LotDTO { ... }
Json Result for HTTP-GET /lot/1
{
"lot": {
"id": 1,
"attributes": "...",
}
}
At least this works for a response with one object.
I haven't figured out how to customize the root name in a collection. #Perceptions' answer might help How to rename root key in JSON serialization with Jackson
EDIT
Solution 2: Without Jackson configuration
Since I couldn't figure out how to customize the json root name in a collection with Kackson
I adapted the answer from #Vaibhav (see 2):
Custom Java Annotation
#Retention(value = RetentionPolicy.RUNTIME)
public #interface CustomJsonRootName {
String singular(); // element root name for a single object
String plural(); // element root name for collections
}
Add annotation to DTO
#CustomJsonRootName(plural = "articles", singular = "article")
public class ArticleDTO { // Attributes, Getter and Setter }
Return a Map as result in Spring Controller
#RequestMapping(method = RequestMethod.GET)
public ResponseEntity<Map<String, List<ArticleDTO>>> findAll() {
List<ArticleDTO> articles = articleService.findAll();
if (articles.isEmpty()) {
return new ResponseEntity<>(HttpStatus.NO_CONTENT);
}
Map result = new HashMap();
result.put(ArticleDTO.class.getAnnotation(CustomJsonRootName.class).plural(), articles);
return new ResponseEntity<>(result, HttpStatus.OK);
}

Answer 3

I found a really easy way to do that. Instead of returning an
ArrayList<Object>
of your objects to the frontend, just return a
HashMap<String, ArrayList<Object>>
and initilize the list of your objects and the according HashMap in the following way:
List<Object> objectList = new ArrayList<>();
... fill your objectList with your objects and then:
HashMap<String, ArrayList<Object>> returnMap = new HashMap<>();
returnMap.put("lot", objectList);
return returnMap;
The head of your controller method looks someting like this:
#ResponseBody
#RequestMapping(value = "/link", method = RequestMethod.POST)
public HashMap<String, List<Object>> processQuestions(#RequestBody List<incomingObject> controllerMethod) {
This will result in the desired JSON without further definitions through annotations or whatever.

Answer 4

I think the easiest way would be to return Map <String, Object>.
Just put the key as 'stores' and object as stores object.
ex-
Map<String, Object> response = new LinkedHashMap<String, Object>();
response.put("stores", stores)