How to retrieve nested family instances in Revit API

Question

I'm using a FilteredElementCollector to retrieve family instances:

    var collector = new FilteredElementCollector(doc, doc.ActiveView.Id);
    var familyInstances = collector.OfClass(typeof(FamilyInstance));

This works fine for families that don't have nested family instances. But if I have in the project instances of family A, and family A itself includes instances of family B, this code doesn't get the instances of family B. How do I get the family B instances?

I'm new to Revit API and it seems like there must be a simple solution but I couldn't find one online. I'm using Revit 2015 if that makes a difference.

Answer 1

the familyInstances will have a list of all the families in the active view (including nested and non-nested ones).

what you need to do is iterate through each FamilyInstance and see if it is already a root family (ie contains nested families) or a nested family or none. something like:

            var collector = new FilteredElementCollector(doc, doc.ActiveView.Id);
            var familyInstances = collector.OfClass(typeof(FamilyInstance));
            foreach (var anElem in familyInstances)
            {
                if (anElem is FamilyInstance)
                {
                    FamilyInstance aFamilyInst = anElem as FamilyInstance;
                    // we need to skip nested family instances 
                    // since we already get them as per below
                    if (aFamilyInst.SuperComponent == null)
                    {
                        // this is a family that is a root family
                        // ie might have nested families 
                        // but is not a nested one
                        var subElements = aFamilyInst.GetSubComponentIds();
                        if (subElements.Count == 0)
                        {
                            // no nested families
                            System.Diagnostics.Debug.WriteLine(aFamilyInst.Name + " has no nested families");
                        }
                        else
                        {
                            // has nested families
                            foreach (var aSubElemId in subElements)
                            {
                                var aSubElem = doc.GetElement(aSubElemId);
                                if (aSubElem is FamilyInstance)
                                {
                                    System.Diagnostics.Debug.WriteLine(aSubElem.Name + " is a nested family of " + aFamilyInst.Name);
                                }
                            }
                        }
                    }
                }
            }