Allow for using MultiValueMap in GET request for mapping multiple request params [SPR-6021]

[spring-projects-issues]

Grzegorz Borkowski opened SPR-6021 and commented

If you send GET request with multiple params (and changing number thereof), instead of writing method like this:

method(@RequestParam String param1, @RequestParam String param2, @RequestParam String param3, @RequestParam String param4, ...)

it would be simpler to use MutliValueMap for this purpose:

method(@RequestParam MutliValueMap params)

(or create new annotation @RequestParams for this purpose)

---

Affects: 3.0 M3

[spring-projects-issues]

Arjen Poutsma commented

Done. Supports both Map<String,String> and MultiValueMap<String,String>.

[spring-projects-issues]

Ganesh Subramanian commented

This fix has introduced another issue. I'm not able to bind a param to a custom map using CustomMapEditor. It always returns either a MutliValueMap or a Map.

The feature requested for is support for a MultiValueMap but at the same time it should allow customization of a Map as well.

Please see below for the suggested fix instead.

private Object resolveRequestParam(String paramName, boolean required, String defaultValue,
			MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
			throws Exception {

		Class<?> paramType = methodParam.getParameterType();
	/*	if (Map.class.isAssignableFrom(paramType)) { */
        // Instead of the checking if its assignable to a map, we can check for a MultiValueMap 
                if (MultiValueMap.class.isAssignableFrom(paramType)) {
			return resolveRequestParamMap((Class<? extends Map>) paramType, webRequest);
		}

[spring-projects-issues]

Arjen Poutsma commented

Indeed, the cutomeditors are overridden in this case. I've fixed it by only allowing the HttpHeaders type to be injected, thus dropping support for Map and MultiValueMap. Since HttpHeaders is a 'well-known' type, it no longer needs a @RequestParam annotation.

[spring-projects-issues]

Grzegorz Borkowski commented

Arjen, what do you mean by "dropping support for MultiValueMap"? We use it in many places, so after upgrading to 3.0.2 our code will blow up?
Request params and request headers are different things, so using HttpHeaders for injecting request params is sementically incorrect.

[spring-projects-issues]

Arjen Poutsma commented

Gregorz,

You are right, I made a mistake. I will revert these changes and find another way to solve the issue that Ganesh reported.

[spring-projects-issues]

Arjen Poutsma commented

My second try at fixing this: we will only do our special Map conversion if the @RequestParam contains no parameter name. So if you want to bind to a specific parameter with your own Map editor, you will have to use something like @RequestParam("map") Map map. This makes sense, because the special Map conversion binds to all request parameters, not just a single one.

[spring-projects-issues]

Ganesh Subramanian commented

Sounds perfect.