public static IDictionary MergeElementTypes(DynaElem FromType, DynaElem ToType) { // Name of Transaction string transactionName = "Merge Element Type"; // Get the Revit elements from the Dynamo Elements RevitDB.ElementType rFromType = (RevitDB.ElementType)FromType.InternalElement; RevitDB.ElementType rToType = (RevitDB.ElementType)ToType.InternalElement; RevitDoc document = rToType.Document; // Collect all instances of FromType RevitDB.FilteredElementCollector collector = new RevitDB.FilteredElementCollector(document); RevitDB.BuiltInParameter parameterId = RevitDB.BuiltInParameter.ELEM_TYPE_PARAM; RevitDB.FilterNumericEquals filterNumberRule = new RevitDB.FilterNumericEquals(); RevitDB.ParameterValueProvider provider = new RevitDB.ParameterValueProvider(new RevitDB.ElementId(parameterId)); RevitDB.FilterRule filterRule = new RevitDB.FilterElementIdRule(provider, filterNumberRule, rFromType.Id); RevitDB.ElementFilter filterParameter = new RevitDB.ElementParameterFilter(filterRule, false); Type instanceType = Select.InstanceClassFromTypeClass(rFromType.GetType()); if (instanceType != null) { collector.OfClass(instanceType); } IEnumerable <RevitDB.Element> instances = collector .WhereElementIsNotElementType() .WherePasses(filterParameter) .ToElements(); // Intialize list for elements that are successfully merged and failed to merge. List <DynaElem> elements = new List <DynaElem>(); List <DynaElem> elementsFailed = new List <DynaElem>(); // Define Function to change instances types. Action <IEnumerable <RevitDB.Element> > _SetType = (isntances) => { foreach (RevitDB.Element elem in instances) { // If Element is in a group, put the element in the failed list int groupId = elem.GroupId.IntegerValue; if (groupId == -1) { //elem.TextNoteType = rToType; RevitDB.Parameter param = elem.get_Parameter(RevitDB.BuiltInParameter.ELEM_TYPE_PARAM); param.Set(rToType.Id); DynaElem dElem = elem.ToDSType(true); elements.Add(dElem); } else { DynaElem dElem = elem.ToDSType(true); elementsFailed.Add(dElem); } } // Check if there are any instances of FromType left int count = collector.Count(); if (count == 0) { document.Delete(rFromType.Id); } }; if (document.IsModifiable) { TransactionManager.Instance.EnsureInTransaction(document); _SetType(instances); TransactionManager.Instance.TransactionTaskDone(); } else { using (Autodesk.Revit.DB.Transaction trans = new Autodesk.Revit.DB.Transaction(document)) { trans.Start(transactionName); _SetType(instances); trans.Commit(); } } return(new Dictionary <string, object> { { "Merged", elements }, { "Failed", elementsFailed } }); }