Model model = new Model(ctx);
Payload payload = ctx.getPayload();
Action action = payload.getAction();
normalize(model, payload);
AppDataGroupByField field = payload.getGroupByField();
String sortBy = payload.getSort();
switch (action) {
case VIEW:
Pair<LineChart, List<AppDataSpreadInfo>> lineChartPair = buildLineChart(model, payload, field, sortBy);