No params in route for ajax post

Question

When I post data to a Scalatra route, no params are seen.

On the client:

$.ajax({
    type: 'POST',
    url: window.location.origin + '/move',
    contentType: 'application/octet-stream; charset=utf-8',
    data: {gameId: 1, from: from.toUpperCase(), to: to.toUpperCase()},
    success: function(result) {
        console.log('ok posting move', result);
    },
    error: function(e) {
        console.log('error posting move', e);
    }
});

In dev tools network view:

Payload
gameId=1&from=B1&to=C3

In Scalatra route:

params("gameId") // -> java.util.NoSuchElementException: key not found: gameId

However, if I change the ajax call by removing the data field and setting the url to:

    type: 'POST',
    url: window.location.origin + '/move?gameId=1&from=' + 
        from.toUpperCase() + '&to=' + to.toUpperCase(),

Then Scalatra can see the params OK, even though it seems wrong to put params in the query string for a post.

Why can't Scalatra see any params when posting data?

Answer 1

You need to use application/x-www-form-urlencoded as content type:

script(type="text/javascript" src="http://code.jquery.com/jquery-1.10.2.min.js")

:javascript
  $(function() {
    $("#btn").click(function() {
      $.ajax({
        type: 'POST',
        url: window.location.origin + '/form',
        contentType: 'application/x-www-form-urlencoded; charset=utf-8',
        data: {gameId: 1, from: "FROM", to: "TO"}
      });
    });
  });


span#btn hello

In your Scalatra application:

post("/form") {
  val payload = for {
    gameId <- params.getAs[Int]("gameId")
    from <- params.getAs[String]("from")
    to <- params.getAs[String]("to")
  } yield (gameId, from, to)

  payload
}       

For details please take a look at the Servlet specification.