Spring Cloud Openfeign @SpringQueryMap doesn't support Map<String, String[]>

Describe the bug @SpringQueryMap doesn't support Map

Sample

@FeignClient(name = "postman-echo", url = "https://postman-echo.com")
public interface PostmanEchoClient {
  @GetMapping(path = "/get")
  Object get(@SpringQueryMap Map<String, String[]> paramMap);
}

Test

Map<String, String[]> paramMap = new HashMap<>(2);
paramMap.put("a", new String[] {"a1", "a2"});
paramMap.put("b", new String[] {"b1", "b2"});

postmanEchoClient.get(paramMap);

Generated url: https://postman-echo.com/get?a=%5BLjava.lang.String%3B%405ed08faf&b=%5BLjava.lang.String%3B%4075386aa2 Expected url: https://postman-echo.com/get?a=a1&a=a2&b=b1&b=b2

Comment From: OLPMO

Has this bug been fixed?@spencergibb And cloud you provide a minimal demo to reproduce this problem? @linianhui

Comment From: OlgaMaciaszek

We've not worked on that yet @OLPMO . Would you like to create a PR?

Comment From: xue8

A key corresponds to a value, so Map <String, String []> does not exist.

Comment From: Junhyunny

Hi, I find out this issue comes from the method which name is "addQueryMapQueryParameters" in ReflectiveFeign class .

link - https://github.com/OpenFeign/feign/blob/master/core/src/main/java/feign/ReflectiveFeign.java

The method only checks Iterable. I think some code should be added like this.

Object currValue = currEntry.getValue();
  if (currValue instanceof Iterable<?>) {
    Iterator<?> iter = ((Iterable<?>) currValue).iterator();
    while (iter.hasNext()) {
            Object nextObject = iter.next();
            values.add(nextObject == null ? null : encoded ? nextObject.toString() : UriUtils.encode(nextObject.toString()));
    }
  } else if (currValue instanceof Object[]) {
    for (Object nextObject : (Object[]) currValue) {
            values.add(nextObject == null ? null : encoded ? nextObject.toString() : UriUtils.encode(nextObject.toString()));
    }
  } else {
    values.add(currValue == null ? null : encoded ? currValue.toString() : UriUtils.encode(currValue.toString()));
  }

thanks.

Comment From: spencergibb

@Junhyunny Then an issue should be opened here https://github.com/OpenFeign/feign/issues

Comment From: Junhyunny

@linianhui, here is my example. You can see the result what you want in log when you use List instead of array.

link - https://github.com/Junhyunny/openfeign-test test - curl localhost:8080/testList

@spencergibb I found out other problem in my example. RequestParam is {a=a1, b=b1}. I expect RequestParam {a=[a1, a2], b=[b1,b2]}. What do you think of this? Is it bug?

Comment From: linianhui

@Junhyunny

List can solve my current problem, Thank you for your help.

Comment From: Junhyunny

@spencergibb I found that result comes from "resolveArgument" method in RequestParamMapMethodArgumentResolver class.

(package org.springframework.web.method.annotation)

Map<String, String> result = new LinkedHashMap<>(parameterMap.size());
parameterMap.forEach((key, values) -> {
    if (values.length > 0) {
        result.put(key, values[0]);
    }
});
return result;

Resolver gets only the first value in list. When I look over the code, I think they intentionally made resolver because they predicted values.

Comment From: spencergibb

Closing in favor of https://github.com/OpenFeign/feign/issues/1170