How to add URL parameter as JSON using Feign framework?

Question

I've made a rest client, using the feign framework, as follows:

@Headers({"Content-Type: application/x-www-form-urlencoded"})
public interface CampaignTrigger {

    @RequestLine("POST /event?actid={actid}&key={key}&event={event}&visit={visit}")
    TriggerResponse trigger(@Param("visit") Map<String, String> visit, @Param("actid") String actid, @Param("key") String key, @Param("event") String event);
}

This results in something like this:

http://www.example.com/event?actid=1234&key=1234&event=cool_event&visit={email=someone@hosting.com}

What I want is for the 'visit' parameter to be a json, like this:

http://www.example.com/event?actid=1234&key=1234&event=cool_event&visit={"email":"someone@hosting.com"}

Who knows how to accomplish this?

Answer 1

You can define your own Param.Expander to achieve it like below.

@Headers({"Content-Type: application/x-www-form-urlencoded"})
public interface CampaignTrigger {

    @RequestLine("POST /event?actid={actid}&key={key}&event={event}&visit={visit}")
    TriggerResponse trigger(@Param(value="visit", expander = JSONExpander.class) Map<String, String> visit, @Param("actid") String actid, @Param("key") String key, @Param("event") String event);
}

static final class JSONExpander implements Param.Expander {
    @Override
    public String expand(Object value) {
         // convert value to json string and return it.
        return xxxx;
    }
}