Download Revit 2013 API Developer Guide - The Building Coder

The IFailuresPreprocessor interface gets control first during the failure resolution process. It is nearly equivalent to checking and resolving failures before finishing a
transaction, except that IFailuresPreprocessor gets control at the right time, after all failures guaranteed to be posted and/or after all irrelevant ones are deleted.
There may be only one IFailuresPreprocessor per transaction and there is no default failure preprocessor. If one is not attached to the transaction (via the failure handling
options), this first step of failure resolution is simply omitted.
Code Region 26-3: Handling failures from IFailuresPreprocessor
public class SwallowTransactionWarning : IExternalCommand
{
public Autodesk.Revit.UI.Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
{
Autodesk.Revit.ApplicationServices.Application app =
commandData.Application.Application;
Document doc = commandData.Application.ActiveUIDocument.Document;
UIDocument uidoc = commandData.Application.ActiveUIDocument;
FilteredElementCollector collector = new FilteredElementCollector(doc);
ICollection<Element> elementCollection =
collector.OfClass(typeof(Level)).ToElements();
Level level = elementCollection.Cast<Level>().ElementAt<Level>(0);
Transaction t = new Transaction(doc);
t.Start("room");
FailureHandlingOptions failOpt = t.GetFailureHandlingOptions();
failOpt.SetFailuresPreprocessor(new RoomWarningSwallower());
t.SetFailureHandlingOptions(failOpt);
doc.Create.NewRoom(level, new UV(0, 0));
t.Commit();
return Autodesk.Revit.UI.Result.Succeeded;
}
}
public class RoomWarningSwallower : IFailuresPreprocessor
{
public FailureProcessingResult PreprocessFailures(FailuresAccessor failuresAccessor)
{
IList<FailureMessageAccessor> failList = new List<FailureMessageAccessor>();
// Inside event handler, get all warnings
failList = failuresAccessor.GetFailureMessages();
foreach (FailureMessageAccessor failure in failList)
{
// check FailureDefinitionIds against ones that you want to dismiss, FailureDefinitionId failID =
failure.GetFailureDefinitionId();
// prevent Revit from showing Unenclosed room warnings
if (failID == BuiltInFailures.RoomFailures.RoomNotEnclosed)
{
failuresAccessor.DeleteWarning(failure);
}
}