In my front end I send this JSON:
"ids": [ 123421, 15643, 51243],
"user": {
"name": "John",
"email": "john#sovfw.com.br"
}
To my Spring Endpoint below:
#PostMapping(value = "/sendToOficial")
public ResponseEntity<?> sendToOficial(#RequestBody Map<String, Object> payload) {
ObjectMapper mapper = new ObjectMapper();
List<Long> pointsIds = mapper.convertValue( payload.get("pointsIds"), List.class );
UsuarioDTO autorAlteracao = mapper.convertValue(payload.get("user"), UsuarioDTO.class);
for (Long idPoint : pointsIds) { ... }
But I'm getting a Cast Exception in the for saying that it can't cast Integer to Long.
I can't receive the "ids" numbers as Integer, I want to receive as Long.
Please, how could I do this?
First, define POJOs for mapping your request object:
public class RequestObj implements Serializable{
private List<Long> ids;
private UsuarioDTO user;
/* getters and setters here */
}
public class UsuarioDTO implements Serializable{
private String name;
private String email;
/* getters and setters here */
}
And then modify your endpoint:
#PostMapping(value = "/sendToOficial")
public ResponseEntity<?> sendToOficial(#RequestBody RequestObj payload) {
In this way you also do not need to use an ObjectMapper. Just call payload.getIds().
Consider also that in this way if payload changes you'll need only to change RequestObj definition, while using ObjectMapper would force you to update also your endpoint in an important way. It's better and safer to separate payload representation from control logic.
In jackson-databind-2.6.x and onward versions you can configure the ObjectMapper to serialize low typed int values (values that fit in 32 bits) as long values using the DeserializationFeature#USE_LONG_FOR_INTS configuration feature:
#PostMapping(value = "/sendToOficial")
public ResponseEntity<?> sendToOficial(#RequestBody Map<String, Object> payload) {
ObjectMapper mapper = new ObjectMapper().configure(DeserializationFeature .USE_LONG_FOR_INTS, true);
List<Long> pointsIds = mapper.convertValue( payload.get("pointsIds"), List.class );
UsuarioDTO autorAlteracao = mapper.convertValue(payload.get("user"), UsuarioDTO.class);
for (Long idPoint : pointsIds) { // ... }
}
If you just want your mapper to read into a List<Long>, use this trick for obtaining full generics type information by sub-classing.
Example
ObjectMapper mapper = new ObjectMapper();
List<Long>listOfLong=mapper.readValue("[ 123421, 15643, 51243]" ,
new TypeReference<List<Long>>() {
});
System.out.println(listOfLong);
Prints
[123421, 15643, 51243]
Related
I have a JSON object similar below:
[
{
"objA": {
"propA": "AAAA",
"propB": "BBBB",
"objB": {
"objC": {
"propC": "CCCC",
"propD": "DDDD"
}
},
"objD": [
"asa"
],
"propE": "AW",
"propF": "533",
"propG": "ABW",
"propH": "ARU",
"objE": {
"objF": {
"propI": "SASDS",
"propJ": "54DEFF"
}
}
}
}
]
When I deserialize this JSON into a List, I would like to do for part of this object, for example: I would like to ignore objB, objC, objD, objE and objF.
To do that I has been used the #JsonIgnore annotation. So I did something like that:
public class MyClass {
// objects and properties not ignorabled
private ClassA objA;
private String propE;
private String propF;
private String propG;;
private String propH;
// objects ignorabled in deserialization
#JsonProperty("objB")
#JsonIgnore
private Object objB;
#JsonProperty("objD")
#JsonIgnore
private Object objD;
#JsonProperty("objE")
#JsonIgnore
private Object objE;
/** gets and setters here **/
Follow below the piece of code that deserialize my JSON
ObjectMapper mapper = new ObjectMapper();
return mapper.readValue(url, new TypeReference<List<MyClass>>(){});
This code is working. this code is ignoring the objects from JSON, but I believe there are some another way to do that instead of use #JsonIgnore to each object or property in my entity.
Do you know how can I do that better?
Do you want to avoid using # notations ?
If not, have you tried using a filter like #JsonFilter("myFilter") in Jackson ? As described here: https://www.baeldung.com/jackson-ignore-properties-on-serialization
See also https://www.tutorialspoint.com/jackson_annotations/jackson_annotations_jsonfilter.htm
So you would have to write:
#JsonFilter("myFilter")
public class MyClass { ... }
in your class. Then do something like:
SimpleBeanPropertyFilter objBFilter = SimpleBeanPropertyFilter
.serializeAllExcept("objB");
SimpleBeanPropertyFilter objDFilter = SimpleBeanPropertyFilter
.serializeAllExcept("objD");
SimpleBeanPropertyFilter objEFilter = SimpleBeanPropertyFilter
.serializeAllExcept("objE");
FilterProvider filters = new SimpleFilterProvider()
.addFilter("objBFilter", theFilter)
.addFilter("objDFilter", theFilter)
.addFilter("objEFilter", theFilter);
I have been stumbled by this for a while. I have a Spring application and would like to parse the following JSON:
{
"metadata": {...}
"response": {
"objects": [
{
"name": "someName",
"properties": [<array_of_properties>]
},
...
]
}
}
into a list of the following Java objects:
public class MyClass {
String name;
List<CustomProperties> customProperties;
}
Meaning, I want to extract only the objects array and parse only that. I have tried using a custom deserializer and that works, but I had to do:
#JsonDeserialize(using=MyDeserializer.class)
public class MyClassList extends ArrayList<MyClass>{}
and then:
ObjectMapper objectMapper = new ObjectMapper();
List<MyClass> list = objectMapper.readValue(json, MyClassList.class)
Is there anyway to avoid extending ArrayList, since currently I am doing that in order to be able to access the .class property.
you can define your json structure with a couple of classes
public class MyJson {
private MyResponse response;
...
}
public class MyResponse {
private List<MyClass> objects;
...
}
public class MyClass {
String name;
List<CustomProperty> customProperties;
...
}
than you can use Jackson to parse the json string to MyJson class, no special #JsonDeserialize is needed
ObjectMapper objectMapper = new ObjectMapper();
MyJson myJson = objectMapper.readValue(json, MyJson.class);
List<MyClass> list = myJson.getResponse().getObjects();
Keep in mind, this code is only a draft, all classes should have setters (and getters) and some null checks are required
You can do something like this. I feel this would be cleaner
#JsonIgnoreProperties(ignoreUnknown = true)
class Wrapper{
private Response response;
//setters, getters
}
#JsonIgnoreProperties(ignoreUnknown = true)
class Response{
private List<MyClass> objects;
//setters, getters
}
#JsonIgnoreProperties(ignoreUnknown = true)
public class MyClass {
String name;
List<CustomProperties> customProperties;
//setters, getters
}
ObjectMapper objectMapper = new ObjectMapper();
Wrapper wrapper = objectMapper.readValue(json, Wrapper.class)
You can extrat objects and consequently CustomProperties by traversing the list. You can declare only fields which you are interested in and ignore others by #JsonIgnoreProperties(ignoreUnknown = true)(for example i have not included metadata)
Our company is planning to switch our microservice technology to Spring Boot. As an initiative I did some advanced reading and noting down its potential impact and syntax equivalents. I also started porting the smallest service we had as a side project.
One issue that blocked my progress was trying to convert our Json request/response exchange to Spring Boot.
Here's an example of the code: (This is Nutz framework for those who don't recognize this)
#POST
#At // These two lines are equivalent to #PostMapping("/create")
#AdaptBy(type=JsonAdapter.class)
public Object create(#Param("param_1") String param1, #Param("param_2) int param2) {
MyModel1 myModel1 = new MyModel1(param1);
MyModel2 myModel2 = new MyModel2(param2);
myRepository1.create(myMode12);
myRepository2.create(myModel2);
return new MyJsonResponse();
}
On PostMan or any other REST client I simply pass POST:
{
"param_1" : "test",
"param_2" : 1
}
I got as far as doing this in Spring Boot:
#PostMapping("/create")
public Object create(#RequestParam("param_1") String param1, #RequestParam("param_2) int param2) {
MyModel1 myModel1 = new MyModel1(param1);
MyModel2 myModel2 = new MyModel2(param2);
myRepository1.create(myMode12);
myRepository2.create(myModel2);
return new MyJsonResponse();
}
I am not sure how to do something similar as JsonAdapter here. Spring doesn't recognize the data I passed.
I tried this but based on the examples it expects the Json paramters to be of an Entity's form.
#RequestMapping(path="/wallet", consumes="application/json", produces="application/json")
But I only got it to work if I do something like this:
public Object (#RequestBody MyModel1 model1) {}
My issue with this is that MyModel1 may not necessarily contain the fields/parameters that my json data has.
The very useful thing about Nutz is that if I removed JsonAdapter it behaves like a regular form request endpoint in spring.
I couldn't find an answer here in Stack or if possible I'm calling it differently than what existing spring devs call it.
Our bosses expect us (unrealistically) to implement these changes without forcing front-end developers to adjust to these changes. (Autonomy and all that jazz). If this is unavoidable what would be the sensible explanation for this?
In that case you can use Map class to read input json, like
#PostMapping("/create")
public Object create(#RequestBody Map<String, ?> input) {
sout(input.get("param1")) // cast to String, int, ..
}
I actually figured out a more straightforward solution.
Apparently this works:
#PostMapping("/endpoint")
public Object endpoint(#RequestBody MyWebRequestObject request) {
String value1 = request.getValue_1();
String value2 = request.getValue_2();
}
The json payload is this:
{
"value_1" : "hello",
"value_2" : "world"
}
This works if MyRequestObject is mapped like the json request object like so. Example:
public class MyWebRequestObject {
String value_1;
String value_2
}
Unmapped values are ignored. Spring is smart like that.
I know this is right back where I started but since we introduced a service layer for the rest control to interact with, it made sense to create our own request model object (DTOs) that is separate from the persistence model.
You can use #RequestBody Map as a parameter for #PostMapping, #PutMapping and #PatchMapping. For #GetMapping and #DeleteMapping, you can write a class which implements Converter to convert from json-formed request parameters to Map. And you would register that class as a bean with #Component annotation. Then you can bind your parameters to #RequestParameter Map.
Here is an example of Converter below.
#Component
public class StringToMapConverter implements Converter<String, Map<String, Object>> {
private final ObjectMapper objectMapper;
#Autowired
public StringToMapConverter(ObjectMapper objectMapper) {
this.objectMapper = objectMapper;
}
#Override
public Map<String, Object> convert(String source) {
try {
return objectMapper.readValue(source, new TypeReference<Map<String, Object>>(){});
} catch (IOException e) {
return new HashMap<>();
}
}
}
If you want to exclude specific field of your MyModel1 class, use #JsonIgnore annotation onto the field like below.
class MyModel1 {
private field1;
#JsonIgnore field2;
}
Then, I guess you can just use what you have done.(I'm not sure.)
public Object (#RequestBody MyModel1 model1) {}
i think that you can use a strategy that involve dto
https://auth0.com/blog/automatically-mapping-dto-to-entity-on-spring-boot-apis/
you send a json to your rest api that is map like a dto object, after you can map like an entity or use it for your needs
try this:
Add new annotation JsonParam and implement HandlerMethodArgumentResolver of this, Parse json to map and get data in HandlerMethodArgumentResolver
{
"aaabbcc": "aaa"
}
#Target(ElementType.PARAMETER)
#Retention(RetentionPolicy.RUNTIME)
public #interface JsonParam {
String value();
}
#Component
public class JsonParamMethodResolver implements HandlerMethodArgumentResolver {
#Override
public boolean supportsParameter(MethodParameter parameter) {
return parameter.hasParameterAnnotation(JsonParam.class);
}
#Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
RepeatedlyRequestWrapper nativeRequest = webRequest.getNativeRequest(RepeatedlyRequestWrapper.class);
if (nativeRequest == null) {
return null;
}
Gson gson = new Gson();
Map<String, Object> response = gson.fromJson(nativeRequest.getReader(), new TypeToken<Map<String, Object>>() {
}.getType());
if (response == null) {
return null;
}
JsonParam parameterAnnotation = parameter.getParameterAnnotation(JsonParam.class);
String value = parameterAnnotation.value();
Class<?> parameterType = parameter.getParameterType();
return response.get(value);
}
}
#Configuration
public class JsonParamConfig extends WebMvcConfigurerAdapter {
#Autowired
JsonParamMethodResolver jsonParamMethodResolver;
#Override
public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
argumentResolvers.add(jsonParamMethodResolver);
}
}
#PostMapping("/methodName")
public void methodName(#JsonParam("aaabbcc") String ddeeff) {
System.out.println(username);
}
I couldn't find an example how to map the following json:
{
"id":1,
"name":"hugodesmarques",
"age":30,
}
To the following java object using jackson:
public class EntityDto {
private Map<String, Object> content;
}
Notice the dto is just a wrapper. What I'm trying to achieve is to have an object EntityDto with a Map{name=>"hugodesmarques", age=>30, id=>1}.
I want to avoid having to map each json field to an object map.
A step back
First of all, the JSON you posted in you question is invalid: there's a comma after 30 and it shouldn't be there. Fix your JSON otherwise Jackson won't parse it:
{
"id": 1,
"name": "hugodesmarques",
"age": 30
}
Parsing the JSON with Jackson
Add a constructor annotated with #JsonCreator to the EntityDto class, as following:
public class EntityDto {
private Map<String, Object> content;
#JsonCreator
public EntityDto(Map<String, Object> content) {
this.content = content;
}
// Getters and setters omitted
}
Then parse the JSON using ObjectMapper:
String json = "{\"id\":1,\"name\":\"hugodesmarques\",\"age\":30}";
ObjectMapper mapper = new ObjectMapper();
EntityDto entityDto = mapper.readValue(json, EntityDto.class);
Structure of class must be like structure of JSON:
public class EntityDto {
int id;
String name;
int age;
}
Jackson can read JSON as a HashMap:
ObjectMapper mapper = new ObjectMapper();
Map<String, Object> map = mapper.readValue("{\"id\":1, \"name\": \"One\"}", HashMap.class);
EntityDto dto = new EntityDto();
dto.setContent(map);
I am new to spring rest and am having problem to map JSON object from jquery to controller. My jquery JSON object have some field absent which are present in java object on controller. Do I have to create new class to map such object or is there any way to map these objects without creating new class?
Here are the code
Controller:
#RequestMapping(value = "/createTest", method = RequestMethod.POST,consumes="application/json")
#ResponseBody
public String createTest(#RequestBody TestJsonDTO testJson)
throws JsonProcessingException, IOException {
//....
TestJsonDTO:
public class TestJsonDTO {
private TestSet testSet;
private List<MainQuestion> questionsInTest;
//gettters and setters
TestSet:
public class TestSet implements Serializable {
public TestSet() {
}
#Id
#GeneratedValue
private int id;
private String name;
private int fullmark;
private int passmark;
String duration;
Date createDate = new Date();
Date testDate;
boolean isNegativeMarking;
boolean negativeMarkingValue;
MainQuestion:
public class MainQuestion implements Serializable {
private static final long serialVersionUID = 1L;
public MainQuestion() {
}
#Id
#GeneratedValue
private int id;
private String name;
and my jquery post method
function createTest() {
$.ajax({
type : 'POST',
url : "http://localhost:8085/annotationBased/admin/createTest",
dataType : "json",
contentType : "application/json",
data : testToJSON(),
success : function() {
alert("success")
},
error : function(msg) {
alert("error while saving test");
}
});
}
function testToJSON() {
listOfQuestionForTest = questionToAdd;//array of ids of questions
return JSON.stringify({
"testSet.name" : $('#testname').val(),
"testSet.fullmark" : parseInt($('#fullmark').val()),
"testSet.passmark" : parseInt($('#passmark').val()),
"questionsInTest" : listOfQuestionForTest
// "testDate":$('#testDate').value()
})
}
In JSON.stringify I am not sending all the fields in TestJsonDto. How can I map this?
You should configure Spring this way:
#Configuration
public class ServiceContext
extends WebMvcConfigurationSupport {
#Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
MappingJackson2HttpMessageConverter converter = this.getMappingJackson2HttpMessageConverter();
converters.add(converter);
}
#Bean
public MappingJackson2HttpMessageConverter getMappingJackson2HttpMessageConverter() {
MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
ObjectMapper objectMapper = this.getObjectMapper();
mappingJackson2HttpMessageConverter.setObjectMapper(objectMapper);
return mappingJackson2HttpMessageConverter;
}
#Bean
public ObjectMapper getObjectMapper() {
JsonFactory jsonFactory = new JsonFactory();
ObjectMapper objectMapper = new ObjectMapper(jsonFactory);
objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); // this is what you need
objectMapper.setSerializationInclusion(Include.NON_NULL); // this is to not serialize unset properties
return objectMapper;
}
}
Here Spring is configured with an ObjectMapper that doesn't serialize properties whose value is null and that doesn't fail on deserialization if some property is missing.
EDIT: (Added some background and explanations)
Spring converts what comes in HTTP request's body into a POJO (that's what #RequestBody actually tells Spring to do). This conversion is performed by a HttpMessageConverter, which is an abstraction. Spring provides default specific message converters for common media types, such as Strings, JSON, form fields, etc.
In your case, you need to tell Spring how to deserialize the incoming JSON, i.e. how to read the JSON that you're sending from jQuery and how to convert this JSON into the POJO you're expecting to receive in your #Controller (TestJsonDTO in your question).
Jackson 2 is a JSON serialization/deserialization library that is widely used. It's most important class is ObjectMapper, which is used to perform the actual serialization and deserialization. Spring has a specific HttpMessageConverter that uses Jackson in order to serialize and deserialize JSON. This is MappingJackson2HttpMessageConverter, which can receive a Jackson's ObjectMapper instance that you can configure if you want to override default behavior.
This ObjectMapper is configured to not serialize properties that are null in your POJO (i.e. your JSON won't contain these properties as fields), and more important, when deserializing, it is configured to not fail with an exception if there is a missing property in either your JSON or your POJO. This is what objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); actually does.