如何在单个 controller / 服务方法中处理多个继承的 DTO？

Question

I have got PaymentTransactionDTO as superclass and subclasses like PhoneBillPaymentTransactionDTO which has a field as phoneNumber etc.

and I would like to handle these DTOs from single payment service. My controller method like below;

public ResponseEntity<TransactionStatus> payment(@PathVariable String accountNumber,
        @Valid @RequestBody PaymentTransactionDTO paymentTransactionDTO)

When I post PhoneBillPaymentTransactionDTO to the method above, I can't reach phoneNumber field as I have PaymentTransactionDTO in the method signature.

How should I have a design to manage multiple inherited dtos from single method?

Answer 1

If using Jackson , you could achieve that with @JsonTypeInfo/@JsonSubTypes on the parent class, but a cast would still be needed to reach phoneNumber.

To avoid any class cast , you'll need to overload your controller method with as many signatures as needed (one per child class of PaymentTransactionDTO at least), and with an explicit JSON structure requirement

// should handle requests containing a phoneNumber attribute
@RequestMapping(method = RequestMethod.GET, params = {"phoneNumber"}) 
public ResponseEntity<TransactionStatus> payment(@PathVariable String accountNumber,
        @Valid @RequestBody PhoneBillPaymentTransactionDTO phoneBillPaymentTransactionDTO) { 
    // code handling specially phone
}

// should handle any request not containing other specified attributes
@RequestMapping(method = RequestMethod.GET) 
public ResponseEntity<TransactionStatus> payment(@PathVariable String accountNumber,
        @Valid @RequestBody PaymentTransactionDTO paymentTransactionDTO) { 
    // code handling the generic transaction
}

Under you can still, from the 'phone' related code, call the base transaction controller method, or also split your controller/service into specific code relying on base implementation.