Spring responds 400 with array query param - spring

Question

I have the following spring boot #RestController request mapping:
#RequestMapping({"/api/blog"})
#RestController
public class BlogController {
#RequestMapping(value = "/test", method = RequestMethod.GET)
public Iterable<Blog> filterBy(
#RequestParam(required = false, name = "filter") String filterStr,
#RequestParam(required = false, name = "range") String rangeStr,
#RequestParam(required = false, name="sort") String sortStr) {
...
}
}
The request should look like so:
GET http://my.api.url/api/blog/test?sort=['title','ASC']&range=[0, 24]&filter={title:'bar'}
However providing any of the array query parameters (range and/or sort) causes a response of 400 with no details other than: "HTTP Status 400 - Bad Request"
Making a request with only the filer query parm works. Adding range and/or sort with null values works. Soon as i add the brackets [] it appears to fail.
I have tried to add the following Exception handler to debug the problem to both the controller and a ControllerAdvice class:
#ExceptionHandler
#ResponseStatus(HttpStatus.BAD_REQUEST)
public void handle(HttpMessageNotReadableException e) {
logger.warn("Returning HTTP 400 Bad Request", e);
}
However this does not get triggered.
I have a suspicion that something is happening in the framework causing the 400 before it even gets to the controller.
Any help is appreciated.

Answer 1

Try defining your parameters as Lists and dont use brackets.
#RequestMapping(value = "/test", method = RequestMethod.GET)
public Iterable<Blog> filterBy(
#RequestParam(required = false, name = "filter") List<String> filterStr,
#RequestParam(required = false, name = "range") List<String> rangeStr,
#RequestParam(required = false, name = "sort") List<String> sortStr) {
filterStr.forEach(s -> System.out.print(", "+ s));
System.out.println();
rangeStr.forEach(s -> System.out.print(", "+ s));
System.out.println();
sortStr.forEach(s -> System.out.print(", "+ s));
System.out.println();
return new ArrayList<>();
}
// test url with mockmvc
#Test
public void filterBy() throws Exception {
mockMvc.perform(get("/test?filter=1,2,3,4&range=5,7,8&sort=desc"))
.andExpect(status().is2xxSuccessful());
}
#Test
public void filterBy() throws Exception {
mockMvc.perform(get("/test?filter=1&filter=2&filter=3&filter=4&range=[5,7,8]&sort=desc"))
.andExpect(status().is2xxSuccessful());
}
For me the first test prints:
, 1, 2, 3, 4
, 5, 7, 8
, desc
The second test prints:
, 1, 2, 3, 4
, [5, 7, 8] // brackets dont seem to work that good
, desc

Answer 2

you have to URL encode your parameters! when you test, you should URL encode the filter, the range and the sort parameters. Try the following:
http://my.api.url/api/blog/test?sort%3D%5B%27title%27%2C%27ASC%27%5D%26range%3D%5B0%2C+24%5D%26filter%3D%7Btitle%3A%27bar%27%7D