Spring boot API, receive generic field

Question

I have a spring boot API . The call is as below:

@PostMapping("/call-back")
    public BaseResponse<String> callBack(@RequestBody CallBackDTO callbackRequest) {
}

the CallBackDTO object is as below:

public class CallBackDTO {
    private String msgRefNo;
    private Object Message;
}

when I pass in this json request, its like below:

{
    "msgRefNo": "202502070000000137"
    "Message": {
        //unknown, random stuff.
    }
}

I am able to receive msgRefNo. But I cant detect Message.How do i save the Message field, with undefined format ?

You can use the JsonNode to represent a JSON object for your Message field. — pebble unit
– pebble unit, Commented Nov 4 at 3:47
Although I did not try, but if structure is nested and you are using Map<String, Object> then same problem will arise again. you can make use of jackson(comes builtin with mvc) or gson(google's library). These 2 libraries help java devs to read data from Json, when type is thing that you are not sure about. — Deepak Kumar
– Deepak Kumar, Commented Nov 4 at 15:59

Deepak Kumar · Accepted Answer · 2025-11-04 15:56:00Z

1

Read about jackson/gson libraries in spring boot, they will be helpful in this case. Replace Object Message with JsonNode (from Jackson).

public class CallBackDTO {
    private String msgRefNo;
    private JsonNode Message;  // <<<<<<<<
    
    // getters and setters
}

Now you can access the unknown fields.

@PostMapping("/call-back") 
public BaseResponse<String> callBack(@RequestBody CallBackDTO callbackRequest) { 
    var data = callbackRequest.getMessage().get("random"); 
}

do exception handling too if field random isn't present in the message.

answered Nov 4 at 15:56

Deepak Kumar

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Issa Khodadadi · Accepted Answer · 2025-11-04 12:52:03Z

0

To add to @Gil's answer, You can use Map<String, Object> in your CallBackDTO as following:

public class CallBackDTO {  
    private String msgRefNo;  
    private Map<String, Object> message;  

    // setter / getter  
}

now your JSON will deserialized to a Map like this:

{     
    "msgRefNo": "20250411070605",     
    "Message": {       
        "keyA": "test",       
        "keyB": 123  
    }   
}

with this approach you could easily invoke each message separately by its key, as follow:

request.getMessage.get("keyA"):   
-\> test

edited Nov 4 at 12:52

answered Nov 4 at 12:46

Issa Khodadadi

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