Revit API & VB.NET - IUpdater Implementation with VB.NET

The IUpdater interface of Revit API provides a means to monitor element status such as addition, deletion, and modification.

The IUpdater has a few methods, for example, Execute, GetAdditionalInformation, GetChangePriority, GetUpdaterId, and GetUpdaterName. The core method is the Execute(). It offers an UpdaterData parameter which provides information about elements just added, deleted, or modified in a document. An UpdaterId instance needs to be created and returned from the GetUpdaterId() method. The GetChangePriority() method indicates changes of what kind of elements should inform the updater first.

The following is a sample implementation in VB.NET:

#Region "Namespaces"

Imports System.Text
Imports System.Linq
Imports System.Xml
Imports System.Reflection
Imports System.ComponentModel
Imports System.Collections
Imports System.Collections.Generic
Imports System.Windows
Imports System.Windows.Media.Imaging
Imports System.Windows.Forms
Imports System.IO

Imports Autodesk.Revit.ApplicationServices
Imports Autodesk.Revit.Attributes

Imports Autodesk.Revit.DB
Imports Autodesk.Revit.DB.Events
Imports Autodesk.Revit.DB.Architecture
Imports Autodesk.Revit.DB.Structure
Imports Autodesk.Revit.DB.Mechanical
Imports Autodesk.Revit.DB.Electrical
Imports Autodesk.Revit.DB.Plumbing

Imports Autodesk.Revit.UI
Imports Autodesk.Revit.UI.Selection
Imports Autodesk.Revit.UI.Events

Imports Autodesk.Revit.Collections
Imports Autodesk.Revit.Exceptions
Imports Autodesk.Revit.Utility

Imports RvtApplication = Autodesk.Revit.ApplicationServices.Application
Imports RvtDocument = Autodesk.Revit.DB.Document

#End Region

Public Class ElementUpdater1
    Implements Autodesk.Revit.DB.IUpdater
    Private mAddinId As Autodesk.Revit.DB.AddInId
    Private mUpdaterId As Autodesk.Revit.DB.UpdaterId

    Public Sub New(ByVal id As Autodesk.Revit.DB.AddInId)
        mAddinId = id
        mUpdaterId = New Autodesk.Revit.DB.UpdaterId(mAddinId, New Guid("69c641d9-c838-42bb-983f-d30b8d01d4bb"))
    End Sub

#Region "IUpdater Members"

    Public Sub Execute(ByVal data As Autodesk.Revit.DB.UpdaterData) Implements Autodesk.Revit.DB.IUpdater.Execute
        Dim doc As Document = data.GetDocument()

        Dim addedIds As ICollection(Of Autodesk.Revit.DB.ElementId) = data.GetAddedElementIds()
        For Each id As Autodesk.Revit.DB.ElementId In addedIds
            Dim elem As Autodesk.Revit.DB.Element = doc.Element(id)
            MessageBox.Show(String.Format("{0}({1}) has been added.", elem.Name, id.IntegerValue))
        Next
        Dim deletedIds As ICollection(Of Autodesk.Revit.DB.ElementId) = data.GetDeletedElementIds()
        For Each id As Autodesk.Revit.DB.ElementId In deletedIds
            MessageBox.Show(String.Format("{0} has been deleted.", id.IntegerValue))
        Next
        Dim modifiedIds As ICollection(Of Autodesk.Revit.DB.ElementId) = data.GetModifiedElementIds()
        For Each id As Autodesk.Revit.DB.ElementId In modifiedIds
            MessageBox.Show(String.Format("{0} has been modified.", id.IntegerValue))
        Next
    End Sub

    Public Function GetAdditionalInformation() As String Implements Autodesk.Revit.DB.IUpdater.GetAdditionalInformation
        Return "ElementUpdater1"
    End Function

    Public Function GetChangePriority() As Autodesk.Revit.DB.ChangePriority Implements Autodesk.Revit.DB.IUpdater.GetChangePriority
        Return Autodesk.Revit.DB.ChangePriority.FloorsRoofsStructuralWalls
    End Function

    Public Function GetUpdaterId() As Autodesk.Revit.DB.UpdaterId Implements Autodesk.Revit.DB.IUpdater.GetUpdaterId
        Return mUpdaterId
    End Function

    Public Function GetUpdaterName() As String Implements Autodesk.Revit.DB.IUpdater.GetUpdaterName
        Return "ElementUpdater1"
    End Function

#End Region
End Class
 
The following code registers the updater against Walls and adds triggers of element addition, deletion and modification in the OnStartup event of an external application:               

 
' Register the ElementUpdater1
Dim updater1 As New ElementUpdater1(uiApp.ActiveAddInId)
Autodesk.Revit.DB.UpdaterRegistry.RegisterUpdater(updater1)
Dim catFilter As New Autodesk.Revit.DB.ElementCategoryFilter(Autodesk.Revit.DB.BuiltInCategory.OST_Walls)
Autodesk.Revit.DB.UpdaterRegistry.AddTrigger(updater1.GetUpdaterId(), catFilter, Autodesk.Revit.DB.Element.GetChangeTypeElementAddition())
Autodesk.Revit.DB.UpdaterRegistry.AddTrigger(updater1.GetUpdaterId(), catFilter, Autodesk.Revit.DB.Element.GetChangeTypeElementDeletion())
Autodesk.Revit.DB.UpdaterRegistry.AddTrigger(updater1.GetUpdaterId(), catFilter, Autodesk.Revit.DB.Element.GetChangeTypeGeometry())

The following code unregisters the updater in the OnShutdown event of the same external application:    

' Unregister the ElementUpdater1
Autodesk.Revit.DB.UpdaterRegistry.UnregisterUpdater(New ElementUpdater1(uiApp.ActiveAddInId).GetUpdaterId())

All the above VB.NET code can be created automatically by the Element Updater of the RevitAddinWizard through a few clicks.