Map parameter as GET param in Spring REST controller

Question

How I can pass a Map parameter as a GET param in url to Spring REST controller ?

Answer 1

It’s possible to bind all request parameters in a Map just by adding a Map object after the annotation:

@RequestMapping("/demo")
public String example(@RequestParam Map<String, String> map){
    String apple = map.get("APPLE");//apple
    String banana = map.get("BANANA");//banana

    return apple + banana;
}

Request

/demo?APPLE=apple&BANANA=banana

Source -- https://reversecoding.net/spring-mvc-requestparam-binding-request-parameters/

Answer 2

There are different ways (but a simple @RequestParam('myMap')Map<String,String> does not work - maybe not true anymore!)

The (IMHO) easiest solution is to use a command object then you could use [key] in the url to specifiy the map key:

@Controller

@RequestMapping("/demo")
public class DemoController {

    public static class Command{
        private Map<String, String> myMap;

        public Map<String, String> getMyMap() {return myMap;}
        public void setMyMap(Map<String, String> myMap) {this.myMap = myMap;}

        @Override
        public String toString() {
            return "Command [myMap=" + myMap + "]";
        }
    }
    
    @RequestMapping(method=RequestMethod.GET)
    public ModelAndView helloWorld(Command command) {
        System.out.println(command);
        return null;
    }
}

• Request: http://localhost:8080/demo?myMap[line1]=hello&myMap[line2]=world
• Output: Command [myMap={line1=hello, line2=world}]

Tested with Spring Boot 1.2.7