Leaflet.draw control for CartoDB

gistfile1.js

function persistOnCartoDB(action,layers) {
var cartodb_ids=[];
var geojsons=[];

switch(action) {
	case "UPDATE":
		if(layers.getLayers().length<1)
			return;
		layers.eachLayer(function(layer) {
			cartodb_ids.push(layer.cartodb_id);
			geojsons.push("'"+JSON.stringify(layer.toGeoJSON())+"'");
		});
		break;

	case "INSERT":
		cartodb_ids.push(-1);
		geojsons.push("'"+JSON.stringify(layers.toGeoJSON())+"'");
		break;

	case "DELETE":
		layers.eachLayer(function(layer) {
			cartodb_ids.push(layer.cartodb_id);
			geojsons.push("''");
		});
		break;
}
var sql = "SELECT osm2_upsert_leaflet_data(ARRAY[";
sql += cartodb_ids.join(",");
sql += "],ARRAY[";
sql += geojsons.join(",");			
sql += "]);";


console.log("persisting... " + sql	);
$.ajax({
    type: 'POST',
    url: 'https://osm2.cartodb.com/api/v2/sql',
    crossDomain: true,
    data: {"q":sql},
    dataType: 'json',
    success: function(responseData, textStatus, jqXHR) {
        console.log("Data saved");

        if(action=="INSERT")
        	layers.cartodb_id = responseData.rows[0].cartodb_id;
    },
    error: function (responseData, textStatus, errorThrown) {
        console.log("Problem saving the data");
    }
});
}

Hi there, this works great, but there is an issue when you want to edit a drawn object without refreshing the page. It will give a "POST 400 (Bad Request)". I saw that it doesn't get the layer.cartodb_id when the page isn't refreshed first. Did you also receive these errors and do you maybe know a fix for this?