@RequestBody variable returning null properties

Question

I wrote a controller for receiving a post request that posts json however when i try to access the object fields it returns null. The code for the Controller is below

package com.example;

import com.example.Services.ZesaServices;
import com.example.models.Zesa.ZesaRequest;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class MoneyResource {

@RequestMapping("/services")
public String getServices(){
    return "We do everything";
}

@PostMapping(value="/zesa")
public String payZesa(@RequestBody ZesaRequest newZesaRequest){

    Logger log = LoggerFactory.getLogger(YomoneyResource.class);
    log.info("Json Object parsed works eg: "+newZesaRequest.getMeterNumber());


    return newZesaRequest.getMeterNumber().toString();
  }
}

And the ZesaRequest Object is as follows

package com.example.models.Zesa;

public class ZesaRequest {
private Double Amount;
private String MeterNumber;
private String PaymentAccountNumber;
private String PaymentAccountDetails;
private int PaymentMethod;
private String MobileNumber;
private String AgentAccountDetails;
private int TransactionType;

public ZesaRequest() {
}


public ZesaRequest(Double amount, String meterNumber, String paymentAccountNumber, String paymentAccountDetails,
                   int paymentMethod, String mobileNumber, String agentAccountDetails, int transactionType) {
    this.Amount = amount;
    this.MeterNumber = meterNumber;
    this.PaymentAccountNumber = paymentAccountNumber;
    this.PaymentAccountDetails = paymentAccountDetails;
    this.PaymentMethod = paymentMethod;
    this.MobileNumber = mobileNumber;
    this.AgentAccountDetails = agentAccountDetails;
    this.TransactionType = transactionType;
}


public String getPaymentAccountDetails() {
    return PaymentAccountDetails;
}

public void setPaymentAccountDetails(String paymentAccountDetails) {
    PaymentAccountDetails = paymentAccountDetails;
}

public String getMobileNumber() {
    return MobileNumber;
}

public void setMobileNumber(String mobileNumber) {
    MobileNumber = mobileNumber;
}


public Double getAmount() {
    return Amount;
}

public void setAmount(Double amount) {
    Amount = amount;
}

public String getMeterNumber() {
    return MeterNumber;
}

public void setMeterNumber(String meterNumber) {
    MeterNumber = meterNumber;
}

public String getPaymentAccountNumber() {
    return PaymentAccountNumber;
}

public void setPaymentAccountNumber(String paymentAccountNumber) {
    PaymentAccountNumber = paymentAccountNumber;
}

public int getPaymentMethod() {
    return PaymentMethod;
}

public void setPaymentMethod(int paymentMethod) {
    PaymentMethod = paymentMethod;
}

public String getAgentAccountDetails() {
    return AgentAccountDetails;
}

public void setAgentAccountDetails(String agentAccountDetails) {
    AgentAccountDetails = agentAccountDetails;
}

public int getTransactionType() {
    return TransactionType;
}

public void setTransactionType(int transactionType) {
    TransactionType = transactionType;
}
}

My code is printing null When I send the request below

{
   "AgentAccountDetails":"example:123",
   "MeterNumber":"1110-52-8867",
   "PaymentMethod":1,
   "Amount":10.50,
   "MobileNumber":"0123456789",
   "TransactionType":1,
   "PaymentAccountNumber":"0123456789",
   "PaymentAccountDetails":"null"
}

When I run it it returns an empty String. I am not sure where the problem is I have looked into other examples and they followed a similar pattern and I ran their code and it worked as expected but mine seems to not be converting the json body into the Java object.

Field names should not start with an uppercase character. – OrangeDog Oct 18 '18 at 09:34 — OrangeDog, Oct 18 '18 at 09:34
You can check my answer ! – Avijit Barua Oct 18 '18 at 11:09 — Avijit Barua, Oct 18 '18 at 11:09

NiVeR · Accepted Answer · 2018-10-18T12:59:51.973

3

You can solve this by using the @JsonProperty annotation above the fields like this:

...
@JsonPropety(value = "Amount")
private Double amount;
...

Or you can rename your properties to start with lowercase letter (both in the VM and in the incoming json), as @OrangeDog suggested in the comments.

edited Oct 18 '18 at 12:59

answered Oct 18 '18 at 09:41

NiVeR

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This is the wrong approach. You now have Jackson making direct access to private fields, and a bunch of pointless getters and setters for an unused property. – OrangeDog Oct 18 '18 at 12:11
I’ve renamed the fields so the bean properties actually work. I’ve also explained what’s going on, and covered the other null issue in the code. – OrangeDog Oct 18 '18 at 12:54

OrangeDog · Answer 2 · 2018-10-22T14:42:10.530

Your class defines a property called meterNumber, but your JSON object says MeterNumber instead.

If you must have MeterNumber in your JSON you will need to add @JsonProperty annotations.

It is against both Java and JSON naming conventions to start field names with a capital letter.

As an aside, you can avoid all the boilerplate by using Lombok:

@Data
public class ZesaRequest {
    @JsonProperty("Amount")
    private Double amount;

    @JsonProperty("MeterNumber")
    private String meterNumber;

    @JsonProperty("PaymentAccountNumber")
    private String paymentAccountNumber;

    @JsonProperty("PaymentAccountDetails")
    private String paymentAccountDetails;

    @JsonProperty("PaymentMethod")
    private int paymentMethod;

    @JsonProperty("MobileNumber")
    private String mobileNumber;

    @JsonProperty("AgentAccountDetails")
    private String agentAccountDetails;

    @JsonProperty("TransactionType")
    private int transactionType;
}

You also probably don't want "PaymentAccountDetails":"null". It should be either "PaymentAccountDetails":null, or omitted entirely.

To be clear, you don't need the `@JsonProperty` annotations if you change the JSON to use the same case as the (correctly-cased) fields. — OrangeDog, Oct 18 '18 at 11:29
@KudzaiMutsvairo "this worked" - then you should upvote and accept this answer. — OrangeDog, Oct 18 '18 at 12:12

@RequestBody variable returning null properties

2 Answers2