Question

I need to develop an Outlook 2010 add-in and I am new to Visual Studio and C#, as I mostly use PHP and JavaScript. I am using Visual Studio 2010 and I’ve created a project using built-in Outlook 2010 add-in template. Consider the folowing code:

// file ThisAddIn.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Xml.Linq;
using Outlook = Microsoft.Office.Interop.Outlook;
using Office = Microsoft.Office.Core;


namespace OutlookAddIn1
{
    public partial class ThisAddIn
    {
        private void ThisAddIn_Startup(object sender, System.EventArgs e)
        {
        }

        private void ThisAddIn_Shutdown(object sender, System.EventArgs e)
        {
        }

        public string displayCount()
        {
            Outlook.MAPIFolder inbox = this.Application.ActiveExplorer().Session.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox);

            Outlook.Items unreadItems = inbox.Items.Restrict("[Unread]=true");

            return string.Format("Unread items in Inbox = {0}", unreadItems.Count);
        }

        #region VSTO generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InternalStartup()
        {
            this.Startup += new System.EventHandler(ThisAddIn_Startup);
            this.Shutdown += new System.EventHandler(ThisAddIn_Shutdown);
        }

        #endregion
    }
}

// file Ribbon1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Office.Tools.Ribbon;

namespace OutlookAddIn1
{
    public partial class Ribbon1
    {
        private void Ribbon1_Load(object sender, RibbonUIEventArgs e)
        {

        }

        private void button1_Click(object sender, RibbonControlEventArgs e)
        {
            // call ThisAddIn.displayCount() here
        }
    }
}

The question is, how do I call public methods from ThisAddIn class in Ribbon1 class or anywhere else? I know that I need an object reference, but how can I find out the name of an instance? I can’t see an instance of ThisAddIn being created anywhere in existing files. Or do I misunderstand the concept and it should be done in other ways? I would appreciate any advice or links to information on creating Office add-ins too.

Answer 1

I use a static member variable (with an associated static getter) that is set upon initialization of the add-in: then I can access it as Core (choose name as appropriate) from anywhere in the code-base. Of course, I try to pass around the add-in object if it is available in context, but sometimes it’s hard to do.

The class is instantiated automatically by the add-in container/loader (it is really exposed as a COM component, at least this is how it works in ADX :).

Happy coding.

---

The code might look something like this:

// inside ThisAddIn class
public static ThisAddIn Active {
  get;
  private set;
}

// inside ThisAddIn_Startup
Active = this;

// later on, after add-in initialization, say in Ribbon1.button1_Click
ThisAddIn.Active.displayCount();