How to pass request param using feign client? - spring-cloud-feign

Question

I am currentlt using Feign Client to call an end point to get outlook mails. But the request parameter are not passing correctly in the api.
#FeignClient(name = "email", url = "${BASE.URI}")
public interface EmailClient {
#GetMapping("/mailfolders/Inbox/messages")
EmailRequestNew getMessages(#RequestHeader HashMap<String, Object> headers,
#RequestParam String filter);
Through service I am calling this Email client to get Mails and passing the filter as
below where from and to are datetime
String param = "$filter=receivedDateTime ge " + from + " and receivedDateTime lt " + to +
"&$expand=singleValueExtendedProperties($filter=id+eq+'String+0x0070')";
but the actual api which are calling is not accurate
assume BASE.URI is something like (10.0.0.120:8080)
https://BASE.URI/mailfolders/Inbox/messages?param=%24filter%3DreceivedDateTime%20ge%202022-11-18T05%3A32%3A56Z%20and%20receivedDateTime%20lt%202022-11-18T09%3A32%3A56Z%26%24expand%3DsingleValueExtendedProperties%28%24filter%3Did%20eq%20%27String%200x0070%27%29
but I want my complete api to be like below when I hardcoded the Request param in the GetMapping
(#GetMapping("/mailfolders/Inbox/messages$filter=receivedDateTime ge 2022-11-18T05:32:56Z and receivedDateTime lt 2022-11-18T09:32:56Z&$expand=singleValueExtendedProperties($filter=id+eq+'String+0x0070')"))
https://dev-api.bhspecialty.com/xchange/v1/mailfolders/Inbox/messages?%24filter=receivedDateTime%20ge%202022-11-18T04:16:58Z%20and%20receivedDateTime%20lt%202022-11-18T08:16:58Z&%24expand=singleValueExtendedProperties($filter=id+eq+'String+0x0070')
How can I achive this.
I tried URL Encoding/Decoding but it is not working.
Example:
URLDecoder.decode(param,"UTF-8")
UriUtils.encodePath(param, "UTF-8");
But nothing is working.

Answer 1

So I was able to do this by creating a RequestInterceptor and then decoding the URI and also change my EmailClient to take PathVariable instead of RequestParam.
#GetMapping(value = "/mailfolders/Inbox/messages?$expand={expand}&$filter={filter}", consumes = MediaType.APPLICATION_JSON_VALUE)
EmailRequestNew getMessages(#RequestHeader HashMap<String, Object> headers,
#PathVariable String filter, #PathVariable String expand);
#Component
public class FeignClientRequestInterceptor implements RequestInterceptor {
private static Logger logger = LogManager.getLogger(FeignClientRequestInterceptor.class);
#Override
public void apply(RequestTemplate template) {
try {
template.uri(URLDecoder.decode(template.request().url(), "UTF-8"));
logger.info("FeignClientRequestInterceptor: " + URLDecoder.decode(template.request().url(), "UTF-8") );
} catch (UnsupportedEncodingException e) {
logger.log(Level.INFO,"Error in FeignClientRequestInterceptor: " + template.request().url() );
throw new RuntimeException(e);
}
}
}
This is the final uri which is created:
https://BASE.URI/mailfolders/Inbox/messages?%24expand=singleValueExtendedProperties($filter=id%20eq%20'String%200x0070')&%24filter=receivedDateTime%20ge%202022-11-21T08:17:59Z%20and%20receivedDateTime%20lt%202022-11-21T12:17:59Z