Question

I’m experimenting with Scala in a spring3 project, and I’m not getting what I expect when I return a map with @ResponseBody. I’m including a working example in java along with my attempt in scala

// This is Java
@RequestMapping(value="/pbx.admin", method=RequestMethod.GET)
public @ResponseBody Map<String, Object> getInfo2(HttpServletRequest request, Model model){
    Map<String, Object> map = new HashMap<String, Object>();
    map.put("pbx", "admin");
    map.put("method", "s");
    return map;
}

The java returns json with the pbx & method defined, which is what I’m expecting.

// This is Scala
@RequestMapping(value= Array("/pbx.admin"), 
  method=Array(RequestMethod.GET))
@ResponseBody
def getInfo2() = {
  Map("pbx" -> "admin", "method" -> "s")
}

The scala returns something different though:

{
    empty: false,
    traversableAgain: true
}

What do I need to do in order to get my map keys / values?

And for extra credit, Is there a better ‘scala way’ to do this? Thanks!

Answer 1

Spring MVC framework wasn’t built with Scala in mind and it doesn’t recognize Scala’s Map. You must convert scala.collection.Map to java.util.Map. You can either use implicit conversion:

import collection.JavaConversions._

def getInfo2(): java.util.Map[String, String] = {
  Map("pbx" -> "admin", "method" -> "s")
}

or convert it manually:

import collection.JavaConverters._

def getInfo2() = {
  Map("pbx" -> "admin", "method" -> "s").asJava
}

Mind the imports, they are important.

I suspect Spring can be hacked to accept Scala collections, but obviously not out-of-the box.