[FIXED] RestTemplate postForEntity return List of DTO

Issue

im working ina spring project and using restemplate to call POST API that take a List of DTOOne And return a List of DTOTWO.

this is my code :

  List<MYDTOONE> listDTORequest;
  //values..
  
  ResponseEntity<List<MYDTOOTWO>> userActionsResponse = restTemplate.postForEntity("my yrl",
    listDTORequest, MYDTOOTWO.class);

im geeting a Syntax error in the last param i need to know how i can tell postForEntity that im waiting for List.

i tried also List<MYDTOOTWO> in the last paramater but still syntax error

thanks in advance.

Solution

You can try to use the following new ParameterizedTypeReference<List< MyDtoTwo>>() {} instead of MYDTOOTWO.class (MyDtoTwo written for ease of reading) with the exchange method (UPDATE: postForEntity has parameterizedTypeReference removed).

What happens in your case is the response you get back is parsed as MYDTOOTWO.class however you're trying to interpret the result as a list, resulting in a mismatch. With parameterized type reference, you can specify that you're expecting a list of MYDTOOTWO.class instead.

Your call should be:

ResponseEntity<List<MYDTOOTWO>> userActionsResponse = exchange("my yrl", HttpMethod.POST,
    listDTORequest, new ParameterizedTypeReference<List< MYDTOOTWO>>() {});

List<MYDTOTWO> body = userActionsResponse.getBody();

UPDATE (as suggested by OP): If you notice, you will need to send the HttpMethod.POST when making a POST request (as the second argument) and wrap your headers and request data in an HttpEntity requestEntity object as follows:

HttpEntity<Object> requestEntity = new HttpEntity<>(listDTORequest, headers);

Answered By - sbsatter
Answer Checked By - David Marino (JavaFixing Volunteer)