为什么我在点击这个 api 时得到一个 null 值？

Question

This is my controller:

@RestController
public class TransactionController {
    
    @Autowired
    TransactionService transactionService;
    
    @PostMapping("/add-transaction")
    public Transaction addTransaction(@RequestBody CustomerTransactions customerTransactions) {
        System.out.println("Check in controller");
        System.out.println(customerTransactions);
        return transactionService.addTransaction(customerTransactions);
    }

}

But the customerTransactions is null. I am sending the JSON request in Postman in the following way:

{
    "Customer":{
        "custName": "Bikash Bhattarai",
        "email": "bksbhattarai@gmail.com",
        "phone": 9818122018
    },
    "Transaction":{
        "custId": "446bdfd3-3d09-43e7-83df-1883f967d296",
        "transdate": "03-04-2023",
        "transamount": 2000
    }
}

This is the console output:

Check in controller
CustomerTransactions [customer=null, transaction=null]
here we go
CustomerTransactions [customer=null, transaction=null]
null
2023-01-01T20:07:08.514+05:45 ERROR 14976 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: java.lang.NullPointerException: Cannot invoke "com.rewardsystem.AugustStore.entities.Customer.getCustId()" because "customer" is null] with root cause

Answer 1

Looks like getter and setter methods are not available in CustomerTransactions , Customer and Transaction classes. Please add getter/setter methods and try again.