Revit二次开发之“修改已经加载的族或系统族的参数”

目前只能修改门，墙，风管都没找到方法。

[Transaction(TransactionMode.Manual)]
[Regeneration(RegenerationOption.Manual)]
public class SetParam : IExternalCommand
{
    public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
    {
        UIDocument uiDoc = commandData.Application.ActiveUIDocument;
        Autodesk.Revit.ApplicationServices.Application app = commandData.Application.Application;

        //门
        string family = "单开门";
        string type = "M0721";
        FamilySymbol fs = FindElementType(uiDoc.Document, typeof(FamilySymbol), family, type, BuiltInCategory.OST_Doors) as FamilySymbol;
        Transaction tr = new Transaction(uiDoc.Document, "test");
        tr.Start();
        foreach (Parameter para in fs.Parameters)
            if (para.Definition.Name == "Height")
                para.Set(mmToFeet(200));
        tr.Commit();

        return Result.Succeeded;
    }
    //毫米到英寸，单位换算
    public double mmToFeet(double val) { return val / 304.8; }
    //通过族名称，族类型，从过滤器中找到指定的类型。
    public Element FindElementType(Document doc, Type targetType, string familyName, string typeName, BuiltInCategory catagory)
    {
        IList<Element> elements = FindSpecialElements(doc, targetType, catagory);

        Element elem = null;
        foreach (Element e in elements)
        {
            if (e.Name.Equals(typeName) &&
                e.get_Parameter(BuiltInParameter.SYMBOL_FAMILY_NAME_PARAM).AsString().Equals(familyName))
            {
                elem = e;
                break;
            }
        }

        return elem;
    }
    //过滤
    //FindSpecialElements(doc, typeof(FamilySymbol), BuiltInCategory.OST_Doors);
    public IList<Element> FindSpecialElements(Document doc, Type targetType, BuiltInCategory catagory)
    {
        FilteredElementCollector collector = new FilteredElementCollector(doc);
        collector.OfClass(targetType);
        if (collector != null)
            collector.OfCategory(catagory);
        IList<Element> elements = collector.ToElements();

        return elements;
    }

}

from:http://revit.5d6d.com/thread-961-1-4.html