Filtering by a Family in Revit API

Question

For a while now I have been looking for a way to filter elements by their family. For example, I want all of the elements that are of family Junction Boxes - Load. I am somewhat new to the Revit API, and I do know about category filters and even a family instance filter. But I do not understand how I get the family symbol for the Junction Boxes - Load family, for example. Is there even a good way of doing this? Or am I better off filtering specific Types within the family? If so, how would I go about doing this?

Answer 1

Jacob,

Jeremy's answer is the right one. Here's an example of code that could be used to get all Family Instances of certain Family name:

The efficient way that Jeremy mentioned would be to use the Parameter Filter:

var famType = new FilteredElementCollector(m_doc)
    .OfClass(typeof(Family)) // This is called a class filter
    .FirstOrDefault(x => x.Name == "YourFamilyName");

if (famType != null)
{
    const BuiltInParameter testParam = BuiltInParameter.ELEM_FAMILY_PARAM;
    var pvp = new ParameterValueProvider(new ElementId((int)testParam));
    var fnrv = new FilterNumericEquals();
    var ruleValId = famType.Id;
    var paramFr = new FilterElementIdRule(pvp, fnrv, ruleValId);
    var epf = new ElementParameterFilter(paramFr);

    var results = new FilteredElementCollector(m_doc)
        .OfClass(typeof(FamilyInstance))
        .WherePasses(epf)
        .ToElements();
}

The less efficient way would be to do this:

var result = new FilteredElementCollector(m_doc)
    .OfClass(typeof(FamilyInstance))
    .Cast<FamilyInstance>()
    .Where(x => x.get_Parameter(BuiltInParameter.ELEM_FAMILY_PARAM).AsValueString() == "YourFamilyName");

I know that Jeremy mentioned that the second method would be less efficient, but I am personally not entirely sure. The ElementParameterFilter is a Slow Filter which expands all of the elements in memory anyways. Event though it's coupled with two Quick Filters for Family and FamilyInstance selection, that's still a considerable overhead as opposed to the more direct approach that you can take using LINQ.

You also asked about being able to select FamilySymbol

var famType = new FilteredElementCollector(m_doc)
        .OfClass(typeof(FamilySymbol))
        .FirstOrDefault(x => x.Name == "YourFamilyTypeName");