Routing Preference with API - no UI

[Anonymous]

Can someone provide me with a clear cut code example of how to set routing preferences using the API only, nothing within the UI? I have googled it, I have looked in the docs, I have looked in the BuildingCoder blog. I have not found anything that works yet. I just need a working code example for C# and revit 2020. 

Thanks in advance.

[Anonymous · Accepted solution]

For anyone having this trouble, I solved it myself.

using (Transaction transaction = new Transaction(doc, "Routing Preference"))
            {
                transaction.Start();

                RoutingPreferenceManager routePrefManager = ductType.RoutingPreferenceManager;
                routePrefManager.PreferredJunctionType = PreferredJunctionType.Tap;

                int initRuleCount = routePrefManager.GetNumberOfRules(RoutingPreferenceRuleGroupType.Junctions);

                for (int i = 0; i != initRuleCount; ++i)
                {
                    routePrefManager.RemoveRule(RoutingPreferenceRuleGroupType.Junctions, 0);
                }
                
                Family tapFam = null;
                FamilySymbol symbol = null;
                string path =
                    @"C:\ProgramData\Autodesk\RVT 2020\Libraries\US Imperial\Duct\Fittings\Round\Taps\Round Takeoff.rfa";
                doc.LoadFamily(path, out tapFam);

                ISet<ElementId> familySymbolIds = tapFam.GetFamilySymbolIds();
                ElementId id = familySymbolIds.ElementAt(0);

                symbol = tapFam.Document.GetElement(id) as FamilySymbol;

                if ((!symbol.IsActive) && (symbol != null))
                {
                    symbol.Activate();
                    doc.Regenerate();
                }

                RoutingPreferenceRule newRule = new RoutingPreferenceRule(symbol.Id, "Round Takeoff");
                routePrefManager.AddRule(RoutingPreferenceRuleGroupType.Junctions, newRule);

                transaction.Commit();
                
            }

[Andrej.Licanin]

Thank you Anon