Spring RestTemplate Send List an get List

Question

I want to make a service with Spring's RestTemplate, in my service side the code is like this :

@PostMapping(path="/savePersonList")
@ResponseBody
public List<Person> generatePersonList(@RequestBody List<Person> person){
    return iPersonRestService.generatePersonList(person);
}

In client side if I call the service with this code:

List<Person> p = (List<Person>) restTemplate.postForObject(url, PersonList, List.class);

I can't use the p object as List<Person>, it will become a LinkedHashList. After some research I find a solution that said I have to call the service with exchange method:

ResponseEntity<List<Person>> rateResponse = restTemplate.exchange(url, HttpMethod.POST, personListResult, new ParameterizedTypeReference<List<Person>>() {});

and with this solution the server can't take the object and raise an exception , what's the correct way?

Solution 1

Check if your code is like below. This should work.

//header
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
//person list
List<Person> personList = new ArrayList<Person>();
Person person = new Person();
person.setName("UserOne");  
personList.add(person);
//httpEnitity       
HttpEntity<Object> requestEntity = new HttpEntity<Object>(personList,headers);
ResponseEntity<List<Person>> rateResponse = restTemplate.exchange(url, HttpMethod.POST, requestEntity,new ParameterizedTypeReference<List<Person>>() {});

Solution 2

It may be helpful for you.

  List<Integer> officialIds = null;
  //add values to officialIds 
  RestTemplate restTemplate = new RestTemplate();

  HttpHeaders headers = new HttpHeaders();

  HttpEntity<List<Integer>> request = new HttpEntity<List<Integer>>(officialIds, 
    headers);

  ResponseEntity<YourResponseClass[]> responses = 
  restTemplate.postForEntity("your URL", request , YourResponseClass[].class );

  List<YourResponseClass> list = Arrays.asList(responses.getBody());

Solution 3

I had similar challenge, and here are my 2 cents.

My Controller Class with POST Mapping

@PostMapping("/fetch/projects")
public ResponseEntity<List<Project>> getAllProjects(@RequestBody List<UserProject> userProject) {
    
    // Convert List of projectIds to List of Long using Lambda Functions
    List<Long> projectIds = userProject.stream().map(UserProject::getProjectId).collect(Collectors.toList());
    
    List<Project> projectList = projectService.getAllProjectsByProjectIds(projectIds);
    
    log.info("<< Fetching Projects based on Project Ids !");
    
    return new ResponseEntity<List<Project>>(projectList, HttpStatus.OK);
}

My Static URL for the above controller

final String projectBaseUri = "http://localhost:6013/api/v1/project/fetch/projects";

My Caller Service

protected List<Project> getProjectsByIds(List<UserProject> userProject) {

    String url = projectBaseUri;
    log.info("Project URL : " + url);

    HttpHeaders headers = new HttpHeaders();
    headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
    headers.setContentType(MediaType.APPLICATION_JSON);
    
    HttpEntity<Object> requestEntity = new HttpEntity<Object>(userProject,headers);

    ResponseEntity<List<Project>> response = restTemplate.exchange(url, HttpMethod.POST, requestEntity,new ParameterizedTypeReference<List<Project>>() {});

    return response.getBody();
}