Why sending a request to controller using Postman runs fine but using RestTemplate throws 500 Internal Server Error? - spring

Question

Context
I have two controllers: /testParams and /callTestParams
Controller /testParams receives an object of type Example and I can call this controller from Postman without any problem.
Controller /callTestParams calls /testParams internally using RestTemplate but the response is a 500 Internal Server Error. I supose that the implementation of /callTestParams is equivalent to the call maded by Postman.
Here is the code:
#RequestMapping(value = "/testParams",
method = RequestMethod.POST, produces = "application/json", consumes = "application/json")
public ResponseEntity<Object> testParams(
#RequestBody Example credentials
) {
JSONObject params = new JSONObject( credentials );
System.out.println( params.get("clientId") + " from JSONObject");
System.out.println( credentials.getClientId() + " from GraphCredentials");
return new ResponseEntity<>(credentials,HttpStatus.OK);
}
#RequestMapping(value = "/callTestParams",
method = RequestMethod.POST, produces = "application/json", consumes = "application/json")
public ResponseEntity<Object> callTestParams() {
String url = "http://localhost:8080/GraphClient/testParams";
HttpHeaders headers = new HttpHeaders();
headers.set( HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE );
JSONObject params = new JSONObject();
params.put("clientId", "value1" );
RestTemplate restTemplate = new RestTemplate();
HttpEntity<?> entity = new HttpEntity<>(params,headers);
HttpEntity<Object> response = restTemplate.exchange(
url,
HttpMethod.POST,
entity,
Object.class
);
return new ResponseEntity<>(response.getBody(), HttpStatus.OK);
}
This is the response from Postman for /testParams
Headers:
(Content-Type,application/json)
Request Body:
JSON (appplication/json)
{"clientId":"value1"}
Response:
{
"clientId": "value1",
"clientSecret": null,
"tenantId": null,
"scope": null,
"grantType": null,
"microsoftLoginBaseURL": "https://login.microsoftonline.com/"
}
This is the response from Postman for /callTestParams
{
"timestamp": "2022-01-09T03:39:06.878+0000",
"status": 500,
"error": "Internal Server Error",
"message": "500 Internal Server Error",
"path": "/GraphClient/callTestParams"
}
This is the error in the console>
Forwarding to error page from request [/testParams] due to exception [JSONObject["clientId"] not found.]: org.json.JSONException: JSONObject["clientId"] not found.

Answer 1

In the parameter of the body of the HttpEntity constructor you need to pass params as String
HttpEntity<?> entity = new HttpEntity<>(params.toString(),headers);