Parameter of Revit API – 3: Convert ParameterSet to List of Parameter - RevitNetAddinWizard & NavisworksNetAddinWizard

In this post, let’s see how to convert a ParameterSet, which can be retrieved from the Element.Parameters property, to a List<Parameter>.

Revit Parameter Organizer can organize various Revit parameters such as Shared Parameters, Family Parameters, Project Parameters and Built-in Parameter in many good ways.

There are three widely used approaches to do so as far as I know. The first one, ENUMERATOR way, is cumbersome and old fashioned but still frequently used especially in legacy code:

Element element = SelectElement(cmdData.Application.ActiveUIDocument.Selection).Element;

                List<Parameter> paramList1 = new List<Parameter>();
                ParameterSet parameterSet = element.Parameters;
                IEnumerator enumerator = parameterSet.GetEnumerator();
                enumerator.Reset();
                while (enumerator.MoveNext())
                {
                    paramList1.Add(enumerator.Current as Parameter);
                }
                MessageBox.Show(paramList1.Count.ToString(), "Count");

We need to get the interface variable of IEnumerator first through calling the GetEnumerator() method, Reset() the enumerator when necessary, MoveNext() one by one to access the Current item, and finally Add it to the List which has to be built up earlier.

The second approach is nicer, which can be called the FOREACH way:

                List<Parameter> paramList2 = new List<Parameter>();
                foreach (Parameter p in element.Parameters)
                {
                    paramList2.Add(p);
                }
                MessageBox.Show(paramList2.Count.ToString(), "Count");

All those GetEnumerator(), Reset(), MoveNext(), and Current stuffs go away and the single FOREACH statement fulfill the same task. So excluding the brackets, only three lines of code is necessary.

The most concise and modern approach is the LINQ way without any doubt:

                List<Parameter> paramList3 = (from Parameter p in element.Parameters select p).ToList();
                MessageBox.Show(paramList3.Count.ToString(), "Count");

A single line of code can loop through all the items in the Element.Parameters property, find the right ones, and create a list for them. And it does not lose any code readability.
The same technique applies to a variety of collections in the Revit API. A few have been listed out below for reference:

ElementSet
CitySet
CategorySet
ConnectorSet
DimensionTypeSet
FamilyParameterSet
FamilyTypeSet
ViewSet
WallTypeSet

RevitAddinWizard exercises the concise and modern way in its Parameter Filter.

Links to some related articles:

Parameter of Revit API - BuiltInParameter

Parameter Retriever of RevitAddCoder

Parameter of Revit API - Parameter Information

Parameter Infoer of RevitAddCoder

Parameter of Revit API - ParameterType And StorageType

Parameter Typer of RevitAddCoder

Parameter of Revit API - BuiltInParameterGroup

Parameter Grouper of RevitAddCoder

Parameter Filter of RevitAddCoder