Beginner’s Guide: Dictionary with the Revit API

A dictionary is a searchable object which uses a unique key and value pairing.  This video helps a beginner to create a dictionary with a key “integer" and “string" value.  Also how to create a dictionary with an “integer" key and "list of string" values.  I populate the dictionary using items from a Revit project using the element id as my keys and parameters/family name as values. 

I cover a simple lambda expression to search the key using a value.  I also use Linq to search for a value using the key.

Sample code:

          public Result Execute(

          ExternalCommandData commandData,

          ref string message,

          ElementSet elements)

        {

            // Revit application documents. 

            UIApplication uiapp = commandData.Application;

            UIDocument uidoc = uiapp.ActiveUIDocument;

            Application app = uiapp.Application;

            Document doc = uidoc.Document;

            Dictionary<int, string> dictionary = new Dictionary<int, string>();

            List<Wall> ListWalls = getWalls(doc);

            foreach (Wall w in ListWalls)

            {

                dictionary.Add(w.Id.IntegerValue, w.Name);

            }

            int key = 928306;

            if (dictionary.ContainsKey(key))

            {

                string value = dictionary[key];

                TaskDialog.Show("value", "Value found by Key: " + value);

            }

            int elemIdKey = dictionary.FirstOrDefault(x => x.Value == "SW24").Key;

            TaskDialog.Show("ElementId", "Key found by Value: " + elemIdKey);

            //List of in dictionary

            Dictionary<int, List<string>> dictionaryList = new Dictionary<int, List<string>>();

            foreach(Wall w in ListWalls)

            {

                List<string> wallValues = new List<string>();

                string Base = w.LookupParameter("Base Constraint").AsValueString();

                string Top = w.LookupParameter("Top Constraint").AsValueString();

                wallValues.Add(w.Name);

                wallValues.Add(Base);

                wallValues.Add(Top);

                dictionaryList.Add(w.Id.IntegerValue, wallValues);

            }

            StringBuilder sb = new StringBuilder();

            foreach (int i in dictionaryList.Keys)

            {

                if (i.Equals(key))

                {

                    foreach (string s in dictionaryList[i])

                    {

                        sb.Append(s + "\n");

                    }

                }

            }

            TaskDialog.Show("value", "Dictionary List \n" + sb.ToString());

            return Result.Succeeded;

        }

Tips:

- Include the using statement for Linq.  

-Watch the previous video to find the get all wall method.