Returns all applicable values for a FamilyType parameter of this family. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 17.0.0.0 (17.0.1090.0) 
  Since:  2016 
Syntax
| C# | 
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| Visual Basic | 
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| Visual C++ | 
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Parameters
- parameterId
-  Type:  Autodesk.Revit.DB ElementId  
 A valid Id of a FamilyType parameter defined for this family.
Return Value
Ids of all applicable ElementType and NestedFamilyTypeReference elements.Remarks
The values are Element Ids of all family types that match the category specified by the definition of the given parameter. The elements are either of class ElementType or NestedFamilyTypeReference . The second variant is for the types that are nested in families and thus are not accessible otherwise.
If there are no applicable types of such category the returned collection will be empty.
Examples
 Copy  C#
 Copy  C# public void GetNestedFamilyTypes(FamilyInstance instance)
{
    // find one FamilyType parameter and all values applicable to it
    Parameter aTypeParam = null;
    ISet<ElementId> values = null;
    Family family = instance.Symbol.Family;
    foreach (Parameter param in instance.Symbol.Parameters)
    {
        if (param.Definition.ParameterType == ParameterType.FamilyType)
        {
            aTypeParam = param;
            values = family.GetFamilyTypeParameterValues(param.Id);
            break;
        }
    }
    if (aTypeParam == null)
    {
        TaskDialog.Show("Warning", "The selected family has no FamilyType parameter defined.");
    }
    else if (values == null)
    {
        TaskDialog.Show("Error", "A FamilyType parameter does not have any applicable values!?");
    }
    else
    {
        ElementId newValue = values.Last<ElementId>();
        if (newValue != aTypeParam.AsElementId())
        {
            using (Transaction trans = new Transaction(instance.Document, "Setting parameter value"))
            {
                trans.Start();
                aTypeParam.Set(newValue);
                trans.Commit();
            }
        }
    }
} Copy  VB.NET
 Copy  VB.NET Public Sub GetNestedFamilyTypes(instance As FamilyInstance)
    ' find one FamilyType parameter and all values applicable to it
    Dim aTypeParam As Parameter = Nothing
    Dim values As ISet(Of ElementId) = Nothing
    Dim family As Family = instance.Symbol.Family
    For Each param As Parameter In instance.Symbol.Parameters
        If param.Definition.ParameterType = ParameterType.FamilyType Then
            aTypeParam = param
            values = family.GetFamilyTypeParameterValues(param.Id)
            Exit For
        End If
    Next
    If aTypeParam Is Nothing Then
        TaskDialog.Show("Warning", "The selected family has no FamilyType parameter defined.")
    ElseIf values Is Nothing Then
        TaskDialog.Show("Error", "A FamilyType parameter does not have any applicable values!?")
    Else
        Dim newValue As ElementId = values.Last()
        If newValue <> aTypeParam.AsElementId() Then
            Using trans As New Transaction(instance.Document, "Setting parameter value")
                trans.Start()
                aTypeParam.[Set](newValue)
                trans.Commit()
            End Using
        End If
    End If
End SubExceptions
| Exception | Condition | 
|---|---|
| Autodesk.Revit.Exceptions ArgumentException | The given parameterId does not represent a valid FamilyType parameter of this family. | 
| Autodesk.Revit.Exceptions ArgumentNullException | A non-optional argument was NULL |