在Revit API中按族进行过滤

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

Welcome to Revit programming!

The most effective way to get started learning and programming with the Revit API, including installation and use of the SDK, is to work through the getting started material, especially the step-by-step instructions provided by the DevTV and My First Revit Plugin video tutorials:

http://thebuildingcoder.typepad.com/blog/about-the-author.html#2

To answer your question: you use filtered element collectors to retrieve elements from the Revit database:

http://www.revitapidocs.com/2017/263cf06b-98be-6f91-c4da-fb47d01688f3.htm

You can apply many filters to them. In your case, you can directly filter for FamilySymbol instances.

There are two ways to limit the search further to retrieve only those you are interested in, named "Junction Boxes - Load" :

• Efficient: use a parameter filter
• Simple: use .NET post-processing or LINQ

More details are provided abundantly by The Building Coder in the topic group on Retrieving Elements Using FilteredElementCollector .

Answer 2

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");