VALIDATE event handler Form D365 FormDataSourceEventType::ValidatingWrite

VALIDATE event handler Form D365 FormDataSourceEventType::ValidatingWrite


How to write a FormDataSourceEventType validate write data event handler code for a Form
 /// <summary>
     /// When saving a new rental, prevent setting the start mileage on the FMRental form to a value that is equal to 1
     /// </summary>
     [FormDataSourceEventHandler(formDataSourceStr(FMRental, FMRental), FormDataSourceEventType::ValidatingWrite)]
     public static void FMRental_OnValidatingWrite(FormDataSource sender, FormDataSourceEventArgs e)
     {
         var datasource = sender as FormDataSource;
         var args = e as FormDataSourceCancelEventArgs;
         if (args != null && datasource != null)
         {
             FMRental record = datasource.cursor() as FMRental;
             if (record.recId == 0)
             {
                 if(record.startmileage == 1)
                 {
                     boolean doCancel = !checkFailed("Start Mileage = 1 is not allowed");
                     args.cancel(doCancel);
                 }
             }
         }
     }
Below is the code at the table level for table FMVehicle
 Class FMVehicleEventHandlers //write any name of the class
 {
     /// <summary>
     ///
     /// </summary>
     /// <param name="sender"></param>
     /// <param name="e"></param>
 [DataEventHandler(tableStr(FMVehicle), DataEventType::ValidatedWrite)]
     public static void FMVehicle_onValidatedWrite(Common sender, DataEventArgs e)
     {
         ValidateEventArgs validateArgs = e as ValidateEventArgs;
         FMVehicle vehicle = sender as FMVehicle;
         boolean result = validateArgs.parmValidateResult();
         if (vehicle.NumberOfCylinders > 8)
         {
             result = checkFailed("Invalid number of cylinders.");
             validateArgs.parmValidateResult(result);
         }
     }
 }