ProjectItemsEvents

by Les Smith

How can I use the ProjectItemsEvents to get notification when an item is added to a VB or C# project, in an add-in?  This is a problem that I struggled with in my early add-in days, and because I could not figure how to get the ProjectItemsEvents to work properly, I went around the world to figure out how to know when a Form or Class was added to the project.  

Like many areas of extensibility in Visual Studio .NET, MSDN documentation is not very helpful on this particular topic.  In this article, I will show you that it is very simple to do, once you see how it is done.  I will illustrate through the description of some code taken directly from an add-in.

First, I will declare two events; one for trapping the addition of a VB Project Item and the other for a C# project.

Public Shared oVS As EnvDTE.DTE     Public WithEvents eventsPIVB As EnvDTE.ProjectItemsEvents     Public WithEvents eventsPICSharp As EnvDTE.ProjectItemsEvents     Dim events As EnvDTE.Events

Next, I will place code in the OnConnection event to sink the event handlers for the two events as follows:

' sink the event handlers for events     events = oVS.Events     eventsPIVB = oVS.Events.GetObject("VBProjectItemsEvents")     eventsPICSharp = oVS.Events.GetObject("CSharpProjectItemsEvents")

The object oVS is my shortened "applicationObject" name supplied to the OnConnection event by the IDE.  Next, I will click on the object drop down list in the Code Window for and choose the WithEvents objects listed above.  Obviously, I will choose one of them and then click on the right hand drop down list, which will have a list of three events.  I will select the ItemAdded event because that is the one in which I am interested.  When I clck on that event, the IDE will create an event handler for me.  Next, I will select the other WithEvents object and repeat these steps to create the second event handler.

Finally, I will place a simple Debug.Writline call in each of the events as follows:

Private Sub eventsPIVB_ItemAdded(ByVal ProjectItem As EnvDTE.ProjectItem) _        Handles eventsPIVB.ItemAdded         Debug.Write("ProjectItemAdded: " & ProjectItem.Name)     End Sub     Private Sub eventsPICSharp_ItemAdded(ByVal ProjectItem As EnvDTE.ProjectItem) _        Handles eventsPICSharp.ItemAdded         Debug.Write("ProjectItemAdded: " & ProjectItem.Name)     End Sub

When I run the add-in the ItemAdded event will fire when I add a new Form or Class to the project.  The event that will fire will be based on the language of the project, either VB or C#.