myapp.Calc.SkipOrder_Tap_canExecute = function (screen) {
var enabledBool = new Boolean;
screen.getOrders().then(function (result) {
enabledBool = (screen.OrderPosition < result.data.length - 1);
});
return enabledBool;
};
The SkipOrder_Tap is a button object in MS LightSwitch. The problem is, I need to return the Boolean AFTER the asynchronous call.
The idea of the promises is to handle asynchronous tasks.
I guess that screen.getOrders() makes asynchronous request and returns a promise. When you use then and pass a callback you will get the orders once the promise is resolved i.e. when your callback passed to then is invoked.
You can proceed as follows, using the promises "chaining":
myapp.Calc.FirstOrder_Tap_canExecute = function (screen) {
return screen.getOrders().then(function (result) {
return (screen.OrderPosition != 0);
});
};
myapp.Calc.FirstOrder_Tap_canExecute()
.then(function (booleanResult) {
//do whatever you need
});
myapp.Calc.SkipOrder_Tap_canExecute should be a synchronous function, than that just wouldn't work.
myapp.Calc.FirstOrder_Tap_canExecute().then(function(enabled) { ...});. Learn more about.then: api.jquery.com/deferred.then