Casting Element as a view (whose category is BuiltInCategory.OST_Viewers)

[EATREVITPOOPCAD]

My understanding is that BuiltInCategory.OST_Viewers is a category for Views. However, having an issue with casting the element as a View.

                    if (sourceElement.Category?.Id.IntegerValue == (int)BuiltInCategory.OST_Viewers)
                    {
                        TaskDialog.Show("News", "Its a view!");

                        View v = sourceElement as View;

                        if (v.ViewType == ViewType.Section)
                        {
                            TaskDialog.Show("News", "Its a section!");
                        }

                        if (v.ViewType == ViewType.Elevation)
                        {
                            TaskDialog.Show("News", "Its an Elevation!");
                        }
                    }

This code works by letting me know "It's a view!" but fails at letting me know if it is a section or an elevation. I get an exception saying can't cast Element as a View. (If I do the (View) cast at least, in the example above v is null)

[jeremy_tammik · Accepted solution]

Yes, indeed. Unfortunately, your assumption is wrong. Revit element categories mostly apply to both element instances and element types. For instance the Wall category includes Wall elements as well as WallType elements. So, for views, the Views category probably includes both different types of views as well as view types. Snooping your BIM database using RevitLookup and other API-based exploration tools provides the safest and most direct way to determine what elements you are dealing with, their category, properties and relationships with other elements.

To filter for a section view, for instance, you can also check the element .NET class in addition to its category, and restrict the filter to ViewSection objects.

[EATREVITPOOPCAD]

Thanks for explaining that. I started with a user-selected object so didn't do the filter. Found 'Family' parameter had what I needed.

if (sourceElement.Category?.Id.IntegerValue == (int)BuiltInCategory.OST_Viewers)
{
    TaskDialog.Show("News", "It's a view!");

    Parameter familyParam = sourceElement.LookupParameter("Family");
    if (familyParam != null)
    {
        string familyValue = familyParam.AsValueString();

        if (familyValue == "Section")
        {
            TaskDialog.Show("News", "It's a Section!");
        }

        if (familyValue == "Elevation")
        {
            TaskDialog.Show("News", "Its an Elevation!");
        }      
    }
}

[jeremy_tammik]

Cool. If your intention is to select a specific type of object, e.g., a specific view type, you can also add a selection filter argument to the PickObject call:

• https://www.revitapidocs.com/2024/3ac1a2c4-9afc-98cf-d5b8-c0c6a15fb4e8.htm
• https://www.revitapidocs.com/2024/d552f44b-221c-0ecd-d001-41a5099b2f9f.htm