Problem with accessing parameter in HTML client, Access is not possible before created.

Question

I have one Screen in which I set a date.
I pass the date to another Screen. In this screen I have a tile list showing all the busses and I want to show the current number of orders of the passed date for each bus.
So I created a custom field in the tile for showing the amount of orders,  and it workes fine for a hardcoded date.
But I have no access to the passed parameter, because it is to early.
I get access after Screen.created to the Parameter, but there it is too late, because the list is already created with 0 as order Count.
myapp.freieBusse.bkz1_render = function (element, contentItem) {
var querybus = contentItem.value;
// var querydatum = new Date(); <=== This works fine for today
var querydatum = screen.queryDatumScreen; <== queryDatumScreen = Null at this Moment.
myapp.activeDataWorkspace.wksqlData.QueryDispoByDatAndBus(querybus,querydatum).execute().then(function (results) {
var countDispo = CountDispo(results);
element.innerHTML = countDispo;
function CountDispo(disposaetze) {
var totalDisp = 0;
var dispos = disposaetze.results;
dispos.forEach(function (dispo) {
totalDisp = totalDisp + 1;
return totalDisp;
How can I get an eralier Access to the Parameter. Or how can I manipulate the order Count of each row in the created of the Screen?
Helmut

Answer 1

The result is as slow that you can count the order with your fingers, but it works.
If you use a
WCF RIA Service the result will be fast. The calculations are performed inside SQL server and returned to the LightSwitch client in a single call per page.
You can also use a Web API call but for a table of data it actually takes a lot of careful JavaScript code and you lose the drag and drop and strong typing in the HTML designer.
Unleash the Power - Get the LightSwitch 2013 HTML Client / SharePoint 2013 book
http://LightSwitchHelpWebsite.com