"Save operation failed" in HTML client screen

Question

Some users of my Lightswitch application are getting an error: "SAVE OPERATION FAILED - Data in the Candidate Basic record is invalid".
Unfortunately I can't see their screens, however I've tried to replicate it myself with their user account and I can't. Does anyone have any idea what is causing this? The application is 3-tier and is hosted on Azure.

Answer 1

You can refer to https://msdn.microsoft.com/en-us/library/vstudio/jj733572.aspx#validate for custom validations.
This does not include validating mandatory entities. For that, go to your property post render and try something along these lines:
contentItem.screen.getMyEntity().then(function (MyEntity) { // just making sure that your entity was loaded
contentItem.dataBind("value", function (newValue) {
if (newValue != null && newValue != undefined) {
contentItem.validationResults = [];
} else {
contentItem.validationResults = [new msls.ValidationResult(contentItem.screen.findContentItem("myPropertyonScreen"), "This field is mandatory")];