Consuming JSON in play! framework controller

Question

I'm trying to consume a JSON array I created using JavaScript but the array is never bound in my controller

Here is the JavaScript code I use to call my controller action

$.post("/produits_ajax",{filterParams:[{name:"milk", value:"chevre"}, {name:"pate", value:"molle"}]},
function(data){
    $('.dynamicContent').html(data);
slideProducts();
// initialize scrollable
$(".scrollable").scrollable();

});

My routes file entry

POST        /produits_ajax       Application.produitsAjax

Here is how I receive it in my play! controller. I'm using play 1.1 and the JsonArray is from com.google.gson.JsonArray

public static void produitsAjax(JsonArray filterParams) {
    if(filterParams != null)
        Logger.debug("Le Json: " + filterParams.toString());
    else
        Logger.debug("filterParams is null");

    render();
}

As you can imagine I always get "filterParams is null" in my console (I wouldn't be writhing this if I wasn't)

It's very basic so far I just want to bind the array generated in JS to my JsonArray. Play!framework has a great documentation but for some reason there is very little on this particular subject.

If anyone can shed some light on this It would be much appreciated

Answer 1

You just have to create a TypeBinder class to add JsonObject binding capacity to Play!. Actually, that's pretty easy to achieve in Play 1.2. Here's the complete class:

@Global
public class JsonObjectBinder implements TypeBinder<JsonObject> {

    @Override
    public Object bind(String name, Annotation[] annotations, String value, Class actualClass, Type genericType) throws Exception {
        return new JsonParser().parse(value);
    }

}

That's it! With the @Global annotation, Play will find it at load time and register this with the other binders. I use this in my controller with the following signature :

public static void handleJsonBody(JsonObject body) {
    ...
}

The body will be automatically parsed by Play. You can do the same for JsonArray to support your particular case.

Answer 2

You have 2 options:

• simple one: pass the parameter as a String and in the controller parse it to Json
• complex one: create your own binder using TypeBinder