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Java Spring, unmarshal dynamic json

I am trying to unmarshal a json response which comes from a server. But I would like to know which is the best way, approach to use when the json response changes.
For example, if I have a json response like this:
{
"name": "John",
"last_name": "John Last name",
"date_of_birth": "01.01.1990"
}
With jackson, I could deserialize the json object into a Person.class like this:
#NoARgsConstructor
#Setter
public class Person(){
private String name;
private String lastName;
private String dateOfBirth;
}
But what if the json struct changes, and now the attributes of the person comes inside a person object.
{
"person": {
"name": "John",
"last_name": "John Last name",
"date_of_birth": "01.01.1990"
}
}
What would be the best way to avoid this things or to avoid this problems? Is there any possible solution or approach to implement in java spring?

How about searching in the JSON yourself?
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
public class Foo {
public static void main(String args[]) throws Exception {
String jsonString = "{\"foo\":\"bar\"}";
ObjectMapper mapper = new ObjectMapper();
ObjectNode node = mapper.readValue(jsonString, ObjectNode.class);
if(node.has("foo")) {
System.out.println("foo: " + node.get("foo"));
}
}
}

To make it completely dynamic, I have used reflection api and json-simple-1.1 jar and jackson
import com.fasterxml.jackson.annotation.JsonProperty;
public class Person {
#JsonProperty("name")
private String name;
#JsonProperty("last_name")
private String lastName;
#JsonProperty("date_of_birth")
private String dateOfBirth;
}
import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Map;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import com.fasterxml.jackson.annotation.JsonProperty;
public class Demo {
public static void main(String a[]) {
try {
String json1 = "{\r\n" + " \"person\": {\r\n" + " \"name\": \"John\",\r\n"
+ " \"last_name\": \"John Last name\",\r\n" + " \"date_of_birth\": \"01.01.1990\"\r\n"
+ " } \r\n" + " }";
String json2 = "{\r\n" + " \"name\": \"John\",\r\n" + " \"last_name\": \"John Last name\",\r\n"
+ " \"date_of_birth\": \"01.01.1990\"\r\n" + "} ";
extractedPersonObject(json1);
System.out.println("*****************************");
extractedPersonObject(json2);
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private static void extractedPersonObject(String json2) throws ParseException {
Person person = new Person();
Object obj = new JSONParser().parse(json2);
JSONObject jo = (JSONObject) obj;
Map finalMap;
Field[] fields = Person.class.getDeclaredFields();
if (jo.get(fields[0].getName()) == null) {
finalMap = ((Map) jo.get("person"));
} else
finalMap = (Map) jo;
for (Field field : fields) {
JsonProperty jsonProperty = field.getDeclaredAnnotation(JsonProperty.class);
invokeSetter(person, field.getName(), finalMap.get(jsonProperty.value()));
}
System.out.println(person.getDateOfBirth());
System.out.println(person.getLastName());
System.out.println(person.getName());
}
public static void invokeSetter(Object obj, String propertyName, Object variableValue) {
PropertyDescriptor pd;
try {
pd = new PropertyDescriptor(propertyName, obj.getClass());
Method setter = pd.getWriteMethod();
try {
setter.invoke(obj, variableValue);
} catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
e.printStackTrace();
}
} catch (IntrospectionException e) {
e.printStackTrace();
}
}
}

A generic way to deserialize such wrapped is to write a deserializer of your own, like:
#SuppressWarnings("serial")
public class UnwrappingDeserializer<T> extends StdDeserializer<T> {
#Setter
private String fieldName;
private ObjectMapper innerMapper = new ObjectMapper();
public UnwrappingDeserializer(Class<T> vc) {
super(vc);
fieldName = handledType().getSimpleName().toLowerCase();
}
#SuppressWarnings("unchecked")
#Override
public T deserialize(JsonParser p, DeserializationContext ctxt)
throws IOException, JsonProcessingException {
JsonNode rootT = p.readValueAsTree();
// Check if there is a node with specified field name.
// There is also a setter for it if the field name is not
// directly resolvable
JsonNode valueT = rootT.get(fieldName);
if (valueT == null) {
// If no such node it is the root tha has the value
valueT = rootT;
}
return innerMapper.convertValue(valueT, (Class<T>)handledType());
}
}
Assuming you have Person as:
#Getter #Setter
// Below is because of your JSON key format
#JsonNaming(PropertyNamingStrategy.SnakeCaseStrategy.class)
public class Person {
private String name;
private String lastName;
private String dateOfBirth;
}
you can just add the deserializer to your ObjectMapper like:
ObjectMapper om = new ObjectMapper();
SimpleModule sm = new SimpleModule();
sm.addDeserializer(Person.class, new UnwrappingDeserializer<Person>(Person.class));
om.registerModule(sm);

How to convert JSON field name to Java bean class property with Jackson

I have access to a RESTful API which returns JSON Strings, such as the following:
{
"Container1": {
"active": true
},
"Container2": {
"active": false
},
}
The problem is that the RESTful API is a bit maldesigned. The field name contains the data already. With the Jackson library it is not possible to deserialize the field name to a property name of the corresponding Java bean class. I assume, this isn't intended by the JSON specification neither. The above JSON string needs to be deserialized to an instance of the following class:
public class Container {
private Boolean active;
private String name;
}
I end up with UnrecognizedPropertyException for the field Container1.
I thought to configure to ignore unknown properties and to provide a JsonDeserializer for that property like this:
#JsonIgnoreProperties(ignoreUnknown = true)
public class Container {
private Boolean active;
private String name;
#JsonDeserialize(using = FieldNameToPropertyDeserializer.class)
public void setName(String name) {
this.name = name;
}
}
and the FieldNameToPropertyDeserializer:
public class FieldNameToPropertyDeserializer extends StdDeserializer<String> {
public FieldNameToPropertyDeserializer() {
super(String.class);
}
#Override
public String deserialize(JsonParser parser, DeserializationContext context) throws IOException, JsonProcessingException {
return parser.getCurrentName();
}
}
The invocation of the deserialization is achieved as follows:
String jsonString = response.readEntity(String.class);
ObjectMapper objectMapper = new ObjectMapper();
ObjectReader readerFor = objectMapper.readerFor(Container.class);
MappingIterator<Container> mappingIterator = readerFor.readValues(jsonString);
while (mappingIterator.hasNext()) {
Container container = (Container) mappingIterator.next();
containers.add(container);
}
But I only receive empty objects (properties set to null) because the parsing of the properties is skipped since I set #JsonIgnoreProperties(ignoreUnknown = true).
Is this possible at all? Or should I implement something like a post-processing afterwards?

How about this. Create a class ContainerActive like this
public class ContainerActive {
private boolean active;
// constructors, setters, getters
}
And you could just do
Map<String, ContainerActive> map = mapper.readValue(jsonString, new TypeReference<Map<String, ContainerActive>>() {});
With this you will have "Container1", "Container2" as the keys and ContainerActive Object as values which has active field.

Just a quick solution, if the object is such that, that all of it object is a container object you can receive the JSON inside and JSONObject you may use below code
import java.io.IOException;
import org.json.JSONException;
import org.json.JSONObject;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class TestSO {
public static void main(String[] args) throws JsonParseException, JsonMappingException, JSONException, IOException {
String jsonString = "{\r\n" +
" \"Container1\": {\r\n" +
" \"active\": true\r\n" +
" },\r\n" +
" \"Container2\": {\r\n" +
" \"active\": false\r\n" +
" },\r\n" +
"}";
JSONObject jsonObject = new JSONObject(jsonString);
ObjectMapper mapper = new ObjectMapper();
for (String key : jsonObject.keySet()) {
Container container = mapper.readValue(jsonObject.get(key).toString(), Container.class);
System.out.println(container);
}
}
static class Container{
private String name;
private Boolean active;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Boolean getActive() {
return active;
}
public void setActive(Boolean active) {
this.active = active;
}
#Override
public String toString() {
return "Container [name=" + name + ", active=" + active + "]";
}
}
}

validate json payload in spring boot rest to throw error if unknown property or empty property has been sent as part of json payload

JSON Request:
{
"notificationType" : "ISSUER_OTP1ee2asasa",
"content" : "hi fff this is fff template content for SBI email good and mobile dfdfdfd and remaining balance is 333 and your name is hahaha.",
"medium" : "EMAIL",
"asa":"ddddd",
"":""
}
POJO:
package com.innoviti.notification.model;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonProperty;
#Document(collection = "NotificationTemplate")
#JsonIgnoreProperties(ignoreUnknown=false)
public class NotificationTemplate {
#JsonCreator
public NotificationTemplate(#JsonProperty(value="notificationType",required=true)String notificationType,
#JsonProperty(value="content",required=true)String content, #JsonProperty(value="medium",required=true)String medium) {
super();
this.notificationType = notificationType;
this.content = content;
this.medium = medium;
}
#Override
public String toString() {
return "NotificationTemplate [id=" + id + ", templateId=" + templateId + ", notificationType="
+ notificationType + ", content=" + content + ", medium=" + medium + "]";
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
#Id
private String id;
private String templateId;
public String getTemplateId() {
return templateId;
}
public void setTemplateId(String templateId) {
this.templateId = templateId;
}
private String notificationType;
private String content;
private String medium;
public String getMedium() {
return medium;
}
public void setMedium(String medium) {
this.medium = medium;
}
public String getNotificationType() {
return notificationType;
}
public void setNotificationType(String notificationType) {
this.notificationType = notificationType;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
}
Controller where payload is posted.
#PostMapping(value = "/config", consumes = MediaType.APPLICATION_JSON_VALUE,
produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<NotificationTemplate> configureTemplate(
#Valid #RequestBody NotificationTemplate notificationTemplate) {
NotificationTemplate notificationTemplatePersisted = null;
logger.info(
"Printing payload of template on server side" + ">>>" + notificationTemplate.toString());
try {
validatePayLoad(notificationTemplate);
notificationTemplatePersisted =
notificationTemplateService.createNotificationTemplate(notificationTemplate);
} catch (Exception de) {
logger.info(String.format("Error in saving template", de.getMessage()));
throw new RequestNotCompletedException(de.getLocalizedMessage());
}
return new ResponseEntity<NotificationTemplate>(notificationTemplatePersisted,
HttpStatus.CREATED);
}
Question:How do I validate that an uknown property has been sent as part of payload.In Existing implementation,#RequestBody maps the json without any issue.I want to throw error or validate payload if incoming json is not confirming exactly to POJO.For e.g in payload example i gave,I want to be able to throw error saying that asa is not recognized property

The Jackson property that controls this behaviour is FAIL_ON_UNKNOWN_PROPERTIES. This needs to be true in your case, to get the behaviour you describe.
It seems that since spring boot 1.2 this is set to false by default.
To set it to true add this line to your application.properties file:
spring.jackson.deserialization.fail-on-unknown-properties=true
And then you will get a JsonMappingException when there are extraneous properties in a JSON payload

One can add this class int their project and it would throw an exception if json is mismatched to the pojo class properties.
#Configuration
public class Config implements InitializingBean {
#Autowired
private RequestMappingHandlerAdapter converter;
#Override
public void afterPropertiesSet() throws Exception {
configureJacksonToFailOnUnknownProperties();
}
private void configureJacksonToFailOnUnknownProperties() {
MappingJackson2HttpMessageConverter httpMessageConverter = converter.getMessageConverters().stream()
.filter(mc -> mc.getClass()
.equals(MappingJackson2HttpMessageConverter.class))
.map(mc -> (MappingJackson2HttpMessageConverter) mc)
.findFirst()
.get();
httpMessageConverter.getObjectMapper().enable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
}
}

printing a json array using jackson

I'm writing a program where I need to get some data from a json file and the content is as below.
{
"culture": "en-us",
"subscription_key": "myKey",
"description": "myDescription",
"name": "myName",
"appID": "myAppId",
"entities": [
{
"name": "Location"
},
{
"name": "geography"
}
]
}
using an online tool I've created the POJOs for the same. and they are as below.
ConfigDetails Pojo
package com.config;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
#JsonInclude(JsonInclude.Include.NON_NULL)
#JsonPropertyOrder({
"culture",
"subscription_key",
"description",
"name",
"appID",
"entities"
})
public class ConfigDetails {
#JsonProperty("culture")
private String culture;
#JsonProperty("subscription_key")
private String subscriptionKey;
#JsonProperty("description")
private String description;
#JsonProperty("name")
private String name;
#JsonProperty("appID")
private String appID;
#JsonProperty("entities")
private List<Entity> entities = null;
#JsonProperty("culture")
public String getCulture() {
return culture;
}
#JsonProperty("culture")
public void setCulture(String culture) {
this.culture = culture;
}
#JsonProperty("subscription_key")
public String getSubscriptionKey() {
return subscriptionKey;
}
#JsonProperty("subscription_key")
public void setSubscriptionKey(String subscriptionKey) {
this.subscriptionKey = subscriptionKey;
}
#JsonProperty("description")
public String getDescription() {
return description;
}
#JsonProperty("description")
public void setDescription(String description) {
this.description = description;
}
#JsonProperty("name")
public String getName() {
return name;
}
#JsonProperty("name")
public void setName(String name) {
this.name = name;
}
#JsonProperty("appID")
public String getAppID() {
return appID;
}
#JsonProperty("appID")
public void setAppID(String appID) {
this.appID = appID;
}
#JsonProperty("entities")
public List<Entity> getEntities() {
return entities;
}
#JsonProperty("entities")
public void setEntities(List<Entity> entities) {
this.entities = entities;
}
}
Entity POJO
package com.config;
import java.util.HashMap;
import java.util.Map;
import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
#JsonInclude(JsonInclude.Include.NON_NULL)
#JsonPropertyOrder({
"name"
})
public class Entity {
#JsonProperty("name")
private String name;
#JsonProperty("name")
public String getName() {
return name;
}
#JsonProperty("name")
public void setName(String name) {
this.name = name;
}
}
and I'm using the below code to print the values from the file.
MainClass obj = new MainClass();
ObjectMapper mapper = new ObjectMapper();
try {
// Convert JSON string from file to Object
ConfigDetails details = mapper.readValue(new File("properties.json"), ConfigDetails.class);
System.out.println(details.getAppID());
List entities = details.getEntities();
for (Object entity : entities) {
System.out.println(entity.toString());
}
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
The output that I'm getting is
MyAppId
com.config.Entity#2096442d
com.config.Entity#9f70c54
here instead of printing the value available, it is printing Hashcode. please let me know how can I print the values.
Thanks

Just access the getter method entity.getName() like this and use Entity instead of Object:
MainClass obj = new MainClass();
ObjectMapper mapper = new ObjectMapper();
try {
// Convert JSON string from file to Object
ConfigDetails details = mapper.readValue(new File("properties.json"), ConfigDetails.class);
System.out.println(details.getAppID());
List entities = details.getEntities();
for (Entity entity : entities) {
System.out.println(entity.getName());
}
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

You haven't defined what it means to convert an "Entity" to a String, so Java is falling back to its default way of doing this (which is to print the class name and an object ID).
What do you mean when you say you want it to "print the value available"? In this case the values are Java objects of type Entity, and you essentially are printing the values.
You can control what the String representation of an object is by overriding the toString() method. For example, you could add the following to the Entity class:
#Override
public String toString() {
return "An entity named " + name;
}

UnrecognizedPropertyException: Unrecognized field not marked as ignorable at Source: org.apache.catalina.connector.CoyoteInputStream#14ec141

I am making rest web-services my code is:
#Path("/add")
#POST
#Produces(MediaType.APPLICATION_JSON)
public Response addMembers(List<GroupMemberMap> groupMemberMaps){
String message = "";
System.out.println("Inside addMembers of class "+this.toString());
try {
DBConnection.insertMembers(groupMemberMaps);
message = "Member(s) added";
return Response.status(Status.CREATED)
.entity(message)
.type(MediaType.TEXT_PLAIN)
.build();
} catch(SQLException sqle){
System.out.println("addMembers catch sqle");
message = "A problem occured while adding members : "+sqle.getMessage();
return Response.status(Status.INTERNAL_SERVER_ERROR)
.entity(message)
.type(MediaType.TEXT_PLAIN)
.build();
}
catch (Exception e) {
// TODO Auto-generated catch block
System.out.println("Inside addMembers catch "+e.getMessage());
message = "A problem occured while adding members : "+e.getMessage();
return Response.status(Status.INTERNAL_SERVER_ERROR)
.entity(message)
.type(MediaType.TEXT_PLAIN)
.build();
}
}
but when i call it with this Json :
[
{
"userId":"3",
"groupId":"4"
}
]
I'm getting following Exception:
javax.servlet.ServletException: org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "userId" (Class com.tazligen.model.GroupMemberMap), not marked as ignorable at [Source: org.apache.catalina.connector.CoyoteInputStream#14ec141; line: 2, column: 15] (through reference chain: com.tazligen.model.GroupMemberMap["userId"])
My GrouMemberMap model class is :
package com.tazligen.model;
#XmlRootElement
public class GroupMemberMap {
private String userId;
private String groupId;
public String getUserid() {
return userId;
}
public void setUserid(String userId) {
this.userId = userId;
}
public String getGroupId() {
return groupId;
}
public void setGroupId(String groupId) {
this.groupId = groupId;
} }
I have tried another method just like this :
#Path("/membertest")
#POST
public String test(List<User> members){
return "Test subresource members working";
}
with json
[{
"userId":"3",
"userName":"John"}]
but this works alright :/
Need Someone help.

I can make following observations after looking at GroupMemberMap Class:
Constructor is missing.
Getter-Setter for the UserId is incorrect.
Also, you can add optional #JsonIgnoreProperties to ignore all other unknown fields.
Here is the corrected code snippet:
package com.tazligen.model;
#XmlRootElement
#JsonIgnoreProperties(ignoreUnknown = true)
public class GroupMemberMap {
#JsonProperty("userId")
private String userId;
#JsonProperty("groupId")
private String groupId;
/* Add Constructor */
public GroupMemberMap() {}
/* Corrected Name */
public String getUserId() {
return userId;
}
/* Corrected Name */
public void setUserId(String userId) {
this.userId = userId;
}
public String getGroupId() {
return groupId;
}
public void setGroupId(String groupId) {
this.groupId = groupId;
}
}

I was using lombok to generate getters and setters with #Getter and #Setter annotation. Now what solved a similar issue for me was converting data type of a field from primary java type boolean to Boolean. Lombok only generated a getter for it only if I used Boolean fieldName.

Just modify userId and groupId public. By default, Jackson works on public member variables.
I think JsonIgnoreProperties is not solution as it is used to ignore whatever it doesn't recognize.
public String userId;
public String groupId;

above solution worked for me and I had string array inside json object .
I used JsonIgnore properties and replaced square brackets for the objects inside json object..