Spring MVC, validate if request has duplicate params - spring

Question

We have multipart post request mapped to below method.
fun post(#RequestParam(value = "photo", required = true) photo: Array<MultipartFile>,
#Valid person: Person)
class Person {
int id,
String name
}
In the below example has more than one name param in the request
localhost:8080/api
post body:
id:101
name: Jhon
name: Jhonny
Is there a way to reject the request if it contains repeated params?

Answer 1

You could add a HttpServletRequest to the handler method argument list, validate it, and return a ReponseEntity.badRequest().build() if there are multiple occurrences of the same parameters.
#GetMapping
public ResponseEntity handlerMethod(HttpServletRequest request) {
if (request.getParameterValues("name").length > 1) {
return ResponseEntity.badRequest().build();
}
return ResponseEntity.ok().build();
}
If you want to do it across the whole application you can define a filter:
#Component
class DuplicateRequestParameterFilter extends OncePerRequestFilter {
Enumeration<String> parameters = request.getHeaderNames();
while (parameters.hasMoreElements()) {
if (request.getParameterValues(parameters.nextElement()).length > 1) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST);
}
}
filterChain.doFilter(request, response);
}

Answer 2

no,there would be a array named 'name' or a string which contain two name,it is looked like this
{id:101,name:'Jhon,Jhonny'} or {id:101,name:['Jhon','Jhonny']}
which is determined by how to receive it
if name is a string ,the result would be 'Jhon,Jhonny'.
if name is a string array ,the result would by ['Jhon','Jhonny'].