Quarkus Kafka Reactive - Deserializing SubClass (ERROR) - java

I am using Quarkus to receive messages from Kafka.
When I use the method with just one class, deserialization happens normally.
When my class is subclassed, I can't continue with the deserialization and an error occurs.
My Input in console kafka:
{"id":"73707ad2-0732-4592-b7e2-79b07c745e45","currentstep":"Debit-approval","payload": "{\"idCard\": 2,\"balance\": 456,\"pin\":222}","sagastatus": "STARTED","stepstatus": "{\"credit-approval\":\"STARTED\"}","type":"order-placement","version": 1}
My Method.
#Incoming("process-transaction-in")
public void process(TransactionModel transaction) throws InterruptedException { }
my deserialize class
import io.quarkus.kafka.client.serialization.ObjectMapperDeserializer;
public class TransactionDeserializer extends ObjectMapperDeserializer<TransactionModel> {
public TransactionDeserializer() {
super(TransactionModel.class);
}
My class Model
public class TransactionModel {
public TransactionModel(String id,
String currentStep,
PayloadModel payload,
String sagaStatus,
String stepStatus,
String type,
String version) {
this.id = id;
this.currentStep = currentStep;
this.payload = payload;
this.sagaStatus = sagaStatus;
this.stepStatus = stepStatus;
this.type = type;
this.version = version;
}
public String id;
public String currentStep;
public PayloadModel payload;
public String sagaStatus;
public String stepStatus;
public String type;
public String version;
public TransactionModel() {
payload = new PayloadModel();
}
}
}
The Class PayloadModel
public class PayloadModel {
public PayloadModel(String idCard,
String current,
String pin)
{
this.idCard = idCard;
this.current = current;
this.pin = pin;
}
public String idCard;
public String current;
public String pin;
public PayloadModel() {}
}
Error:
SRMSG18249: Unable to recover from the deserialization failure (topic: process-transaction), configure a DeserializationFailureHandler to recover from errors.: java.lang.RuntimeException: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of payment.model.PayloadModel (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('{"idCard": 2,"balance": 456,"pin":222}')
I followed the following tutorial: https://quarkus.io/guides/kafka#kafka-serialization
Has anyone experienced this problem?

As you can see in the error log Jackson finds at least one constructor for PayloadModel class but it's not the one it's expecting since the "payload" parameter in your Kafka payload is a string and not a JSON Object. Try to change the way you serialize your data so that payload is serialized as an object.
Sorry for posting this as a response I don't have enough reputation to comment.

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Parse two different API response using Retrofit 2 in Android

I am facing a problem while parsing API response using Retrofit 2.
The API's are already in production and I cannot request a change in API.
Following are two different responses I am getting from server
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{
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"empId":121,
"message":"Data available",
"data":{
"name":"Sam",
"designation": "Software Engineer",
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Failure response
{
"status":10,
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"data":""
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Parsing Classes
class Response{
public int status;
public String message;
public int empId;
public Student data;
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public String name;
public String designation;
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I am able to parse the success response. But getting the following exception for the failure case.
java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING
try this ,
Object getrow = null;
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getrow = this.// your object
LinkedTreeMap<Object, Object> tree = (LinkedTreeMap) getrow;
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} catch (Exception e) {
e.printStackTrace();
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The way that you can handle this situation is by treating 'data' as a generic object rather than as a String or 'Student'.
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public Object data;
While Using data add a check like this
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class Response
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Converting json string to generic Map using Jackson

I am getting the following object from a different service and I need to parse it into a POJO I have in my service. The incoming object looks like:
AddressMessage.java
public class AddressMessage {
#NotEmpty
#JsonProperty("id")
private String id;
#NotEmpty
#JsonProperty("address")
private String address;
public String getId() {
return this.id;
}
public String getAddress() {
return this.address;
}
#SuppressWarnings("unchecked")
#JsonProperty("data")
public void unpackNested(Map<String, Object> rawMessage) {
Map<String, String> data = (Map<String, String>) rawMessage.get("data");
this.id = (String) data.get("id");
this.address = (String) data.get("address");
}
}
and the incoming data looks like:
{“data”: { “id” : “sampleId”, “address”: “sampleAddress” }}
I've tried parsing the incoming json string to a plain Object but that didn't work:
private void publishMessage(String rawMessage, AMQP.BasicProperties props) throws IOException {
Object json = objectMapper.readValue(rawMessage, Object.class);
log.debug(objectMapper.writeValueAsString(json));
I also tried taking in the raw message and mapping it directly to the class using the object mapper like this:
private void publishMessage(String rawMessage, AMQP.BasicProperties props) throws IOException {
AddressMessage addressMessage = objectMapper.readValue(rawMessage,
AddressMessage.class);
}
Exception for above code:
Unexpected character ('“' (code 8220 / 0x201c)): was expecting double-quote to start field name
I want to pull the "id" and "address" properties out of the object but I keep running into exception due to parsing errors. Some guidance will be greatly appreciated, thanks!
Addition: I am not currently using the "unpackNested" method but thought i'd throw it in there in case it sparks any idea
You can use the #JsonCreator annotation on a constructor like this:
#JsonCreator
public AddressMessage(#JsonProperty("data") Map<String, Object> rawJson) {
this.id = rawJson.get("id").toString();
this.address = rawJson.get("address").toString();
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This tells Jackson to use that constructor when deserializing.

Serialize and deserialize a field according to another field value

How can I serialize or deserialize a field, according to another field value within the same class?
In the following example, when serializing or deserializing Packet class, I would like that type field will determine how payload field will be serialized and deserialized.
PayloadType enum
public enum PayloadType {
HTTP,
HTTPS,
FTP
}
Packet class
public class Packet {
private final String payload;
// This field should determine how "payload" field is serialized.
private final PayloadType type;
private final Date creationTime;
#JsonCreator
public Packet(String payload, PayloadType type) {
this.payload = payload;
this.type = type;
this.creationTime = new Date();
}
public String getPayload() {
return this.payload;
}
public PayloadType getType() {
return this.type;
}
public Date getCreationTime() {
return this.creationTime;
}
Test
public class PacketTests {
#Test
public void packetSerialization_fromHttpType() throws JsonProcessingException {
// Given
ObjectMapper jackson = new ObjectMapper();
String payload = "hello world";
PayloadType type = PayloadType.HTTP;
Packet packet = new Packet(payload, type);
String json;
// When
json = jackson.writeValueAsString(packet);
// Then
System.out.println(json);
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Current output
{"payload":"hello world","type":"HTTP","creationTime":1542538836041}
Expected outputs
{"payload":"(http) hello world","type":"HTTP","creationTime":1542538836041}
{"payload":"(https) hello world","type":"HTTPS","creationTime":1542538836041}
{"payload":"X9hnahj83","type":"FTP","creationTime":1542538836041}
The payload of FTP is base64 string.
Similar to # comment update the payload getter to return different output values
public String getPayload() {
return "(" + getType().name().toLowerCase() + ") " + this.payload;
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Binding JSON to Arraylist in Java Spring?

I want to be able to pass in data from a POST request and hit my API in which the JSON I pass through binds to the POTD class. Within POTD, I have an ArrayList of type POTDResources, which is where I am having trouble binding the data.
I'm eventually just going to use the entire Problem object, but for right now I am just testing with two fields within the class.
I need the JSON input to be able to bind to an ArrayList of type POTDResources
I'm passing in data like the following:
{
"problemTitle": "Balancing Binary Tree",
"resources": [{"name": "youtube", "link": "http://yotube.com"}]
}
The API call first hits:
Controller
#RequestMapping(value = "/generatepotd", method = RequestMethod.POST)
#ResponseBody
public void generatePOTD(#RequestBody POTD problem) throws IOException {
POTD prob = new POTD();
prob.setProblemTitle(problem.getProblemTitle());
prob.setResources(problem.getResources());
tempGen.generateProblemOfTheDay(prob);
}
POTD Class
package com.algoq.algoq.models;
import org.springframework.context.annotation.Description;
import java.util.ArrayList;
#Description("Handles the fields required for processing problem of the day")
public class POTD {
private String subject;
private String problemTitle;
private String problemDescription;
private ArrayList<POTDResources> resources;
// POTD(String subject, String problemTitle, String problemDescription, ArrayList<POTDResources> resources) {
POTD(String problemTitle, ArrayList<POTDResources> resources) {
// this.subject = subject;
this.problemTitle = problemTitle;
// this.problemDescription = problemDescription;
this.resources = resources;
}
public POTD() {
}
public String getSubject() {
return subject;
}
public void setSubject(String subject) {
this.subject = subject;
}
public String getProblemTitle() {
return problemTitle;
}
public void setProblemTitle(String problemTitle) {
this.problemTitle = problemTitle;
}
public String getProblemDescription() {
return problemDescription;
}
public void setProblemDescription(String problemDescription) {
this.problemDescription = problemDescription;
}
public ArrayList<POTDResources> getResources() {
return resources;
}
public void setResources(ArrayList<POTDResources> resources) {
this.resources = resources;
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}
POTD Resource Class
package com.algoq.algoq.models;
public class POTDResources {
private String name;
private String link;
public POTDResources(String name, String link) {
this.name = name;
this.link = link;
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return name;
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public void setName(String name) {
this.name = name;
}
public String getLink() {
return link;
}
public void setLink(String link) {
this.link = link;
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Error Message
{
"timestamp": 1513192593064,
"status": 400,
"error": "Bad Request",
"exception": "org.springframework.http.converter.HttpMessageNotReadableException",
"message": "JSON parse error: Can not construct instance of com.algoq.algoq.models.POTDResources: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.algoq.algoq.models.POTDResources: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?)\n at [Source: java.io.PushbackInputStream#1710624f; line: 3, column: 17] (through reference chain: com.algoq.algoq.models.POTD[\"resources\"]->java.util.ArrayList[0])",
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Your problems lies with the error message:
no suitable constructor found
You are overriding the default constructor, and the ObjectMapper can't create an instance of your Model class.
Try to add a default constructor for POTDResources:
public POTDResources() {
}
Jackson, which is used by Spring for JSON and XML processing, can work 2 ways with Object.
Constructor and Setter based.
If it can find a constructor with the same field names and types, it will try to use that one. If no suitable constructor, then it will try to create an instance of the object, and use setters. You didn't have a suitable constructor and it failed to create the instance.
Add empty constructor to your POTDResources class:
public POTDResources() {}
The reason being that JSON mapper would first try to initialize your class, and only then would apply values to it
Your problem is that POTDResources does not have a default constructor:
public POTDResources() {}
Jackson requires a no-arg constructor.

JSON.decodeValue Decode Exception

I want to make this java code works:
RequestManager rm = Json.decodeValue(request.getBodyAsString(), RequestManager.class);
But i have this error:
io.vertx.core.json.DecodeException: Failed to decode:No suitable constructor found for type [simple type, class RequestManager]: can not instantiate from JSON object (missing default constructor or creator, or perhaps need to add/enable type information?)
at [Source: {"messageId":"fsdfsdf"}; line: 1, column: 2]
And here the code of my class :
public class RequestManager {
private String messageId;
private String messageContent;
public RequestManager(String messageId, String messageContent) {
this.messageId = messageId;
this.messageContent = messageContent;
}
public String getMessageId() {
return messageId;
}
public String getMessageContent() {
return messageContent;
}
}
I really don't know why it's not working and there is only few topics about it, but they were irrelevant.
Someone can help ?
EDIT--
I know have the RequestManager class like this:
public class RequestManager {
private String messageId;
private String messageContent;
public RequestManager(String messageId, String messageContent) {
this.messageId = messageId;
this.messageContent = messageContent + "check";
}
public RequestManager() {
}
public String getMessageId() {
return messageId;
}
public String getMessageContent() {
return messageContent;
}
public void setMessageId(String messageId) {
this.messageId = messageId;
}
public void setMessageContent(String messageContent) {
this.messageContent = messageContent;
}
}
But know when i try to print the fields of my RequestManager object created with the JSON.decodeValue it's return me null. I've already done that in the past and had the same error. I think it's because the empty constructor is used instead.
I still don't really understand....
EDIT--2
I have tried to change my class again, here it is:
#JsonIgnoreProperties(ignoreUnknown=true)
public class RequestManager {
#JsonProperty("messageId") private String messageId;
#JsonProperty("messageContent") private String messageContent;
#JsonCreator
public RequestManager(#JsonProperty("messageId") String messageId, #JsonProperty("messageContent") String messageContent) {
this.messageId = messageId;
this.messageContent = messageContent;
System.out.println("This constructor is used.");
}
public RequestManager() {
}
public String getMessageId() {
return messageId;
}
public String getMessageContent() {
return messageContent;
}
public void setMessageId(String messageId) {
this.messageId = messageId;
}
public void setMessageContent(String messageContent) {
this.messageContent = messageContent;
}
}
And this is in my main :
final RequestManager rm = Json.decodeValue("{\"messageId\":\"themessage\"}", RequestManager.class);
System.out.println(rm.getMessageContent());
"{\"messageId\":\"themessage\"}" = the JSON format, i'm sure of it because decodeValue would return a Decode Exception if it wasn't.
Now the field is "nullcheck" when i print it. So it means that the constructor is well used but the fields are nulls. Where am i doint it wrong ?
You could try to have an empty constructor.
It's because you have your own constructor, and JSON doesn't know what values should be passed into it.
There is documentation on their GitHub page explaining how to set up a data object that you expect to be given to you as JSON and converted to Java.
https://github.com/vert-x3/vertx-codegen#data-objects
As per the example that you linked to: http://vertx.io/blog/some-rest-with-vert-x/, notice how they explicitly provide a constructor that takes no arguments, and public setter methods
Whisky()
setName(String name)
setOrigin(String origin)
The alternative is to provide annotations: https://github.com/FasterXML/jackson-annotations. You can choose how to do it, using annotation if you want, or using a bean class (getters and setters). Annotation has the advantage that you can say things like "ignore this value when you convert to JSON", etc. You can be more explicit with annotation. I would recommend picking one and staying with it. Consistency becomes important as your projects grow.

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