How to pass List or String array to getForObject with Spring RestTemplate

Question

I am developing some restful services with Spring. I have trouble with passing/getting string array or large string as parameters to my service controller. My code examples are like below;

Controller:

@RequestMapping(value="/getLocationInformations/{pointList}", method=RequestMethod.GET)
@ResponseBody
public LocationInfoObject getLocationInformations(@PathVariable("pointList") String pointList)
{
    // code block
}

Sample point list:

String pointList = "37.0433;35.2663,37.0431;35.2663,37.0429;35.2664,37.0428;35.2664,37.0426;35.2665,37.0424;35.2667,37.0422;35.2669,37.042;35.2671,37.0419;35.2673,37.0417;35.2674,37.0415;35.2674,37.0412;35.2672,37.0408;35.267,37.04;35.2667,37.0396;35.2665,37.0391;35.2663,37.0388;35.2662,37.0384;35.266,37.0381;35.2659,37.0379;35.2658,37.0377;35.2657,37.0404;35.2668,37.0377;35.2656,37.0378;35.2652,37.0378;35.2652,37.0381;35.2646,37.0382;35.264,37.0381;35.2635,37.038;35.263,37.0379;35.2627,37.0378;35.2626,37.0376;35.2626,37.0372;35.2627,37.0367;35.2628,37.0363;35.2628,37.036;35.2629,37.0357;35.2629,37.0356;35.2628,37.0356;35.2628,37.0355;35.2626";

Web service client code:

Map<String, String> vars = new HashMap<String, String>();
vars.put("pointList", pointList);

String apiUrl = "http://api.website.com/service/getLocationInformations/{pointList}";

RestTemplate restTemplate = new RestTemplate();
LocationInfoObject result = restTemplate.getForObject(apiUrl, LocationInfoObject.class, vars);

When I run client side application, it throws a HttpClientErrorException: 400 Bad Request, I think long location information string causes to this problem. So, how can I solve this issue? Or is it possible posting long string value as parameter to web service?

Thx all

Answer 1

List or other type of objects can post with RestTemplate's postForObject method. My solution is like below:

controller:

@RequestMapping(value="/getLocationInformations", method=RequestMethod.POST)
@ResponseBody
public LocationInfoObject getLocationInformations(@RequestBody RequestObject requestObject)
{
    // code block
}

Create a request object for posting to service:

public class RequestObject implements Serializable
{
    public List<Point> pointList    = null;
}

public class Point 
{
    public Float latitude = null;
    public Float longitude = null;
}

Create a response object to get values from service:

public class ResponseObject implements Serializable
{
    public Boolean success                  = false;
    public Integer statusCode               = null;
    public String status                    = null;
    public LocationInfoObject locationInfo  = null;
}

Post point list with request object and get response object from service:

String apiUrl = "http://api.website.com/service/getLocationInformations";
RequestObject requestObject = new RequestObject();
// create pointList and add to requestObject
requestObject.setPointList(pointList);

RestTemplate restTemplate = new RestTemplate();
ResponseObject response = restTemplate.postForObject(apiUrl, requestObject, ResponseObject.class);

// response.getSuccess(), response.getStatusCode(), response.getStatus(), response.getLocationInfo() can be used

Answer 2

The question is related to GET resource, not POST. Because of that I think that "accepted answer" is not the correct one.

So for other googlers like me that finds this, Ill add what helps me:

GET resources can receive a string list via @PathVariable or @RequestParam and even correctly bind it to a List<String> if you do pass the list separated by ,.

Your API can be:

@RequestMapping(value="/getLocationInformations/{pointList}", method=RequestMethod.GET)
@ResponseBody
public LocationInfoObject getLocationInformations(@PathVariable("pointList") List<String> pointList) {
    // code block
}

And your call would be:

List<String> listOfPoints = ...;
String points = String.join(",", listOfPoints);

String apiUrl = "http://api.website.com/service/getLocationInformations/{pointList}";
LocationInfoObject result = restTemplate.getForObject(apiUrl, LocationInfoObject.class, points);

Note that you must send lists to API using , as separator, otherwise the API cannot recognize it as a list. Also you cannot just add your list directly as a parameter, because depending on how it's mashalled the generated string may not be compatible.

Answer 3

Firstly you've passed a map as parameters but your controller expects these as a path variable. All you need to do is make the 'pointlist' value part of the URL (without the curly bracket placeholders). e.g.:-

http://api.website.com/service/getLocationInformations/pointList

Next you need to ensure you have message converters set up so that your LocationInfoObject is marshalled into an appropriate representation (suggest JSON) and unmarshalled the same way.

For the Rest template:

restTemplate.setMessageConverters(...Google MappingJackson2HttpMessageConverter...);

For the server you just need to add Jackson to the classpath (if you want multiple representations you'd need to configure each one manually - Google will be your friend here aswell.