Best way to find all Outlook calendars in all accounts - vba

Question

I have an application that uses the COM interface to communicate with Outlook.
I have a dropdown box, which has all the calendars from all the accounts.
There are some reported cases, where using exchange and Outlook 2010, the application hangs when loading the list of calendars. Could it be, that it has something to do with the code (shown below) or an anti-virus blocking the access for the address information?
It randomly fails for some Exchange accounts.
private void AppLoad(object sender, EventArgs e)
{
Outlook.Application msOutlook = new Outlook.Application();
Outlook.NameSpace session = msOutlook.Session;
Outlook.Stores stores = session.Stores;
foreach (Outlook.MAPIFolder folder in session.Folders)
{
GetFolders(folder, msOutlook);
}
if(calendarSelector.Items.Count==0)
{
StoreAndCalendar ci = new StoreAndCalendar();
ci.Text = "Default";
ci.Account = "Noaccount";
ci.Storename = "Noaccount";
ci.Value = "Noaccount";
calendarSelector.Items.Add(ci);
}
else
{
try
{
calendarSelector.SelectedIndex = 0;
}
catch { }
}
//preselect default calendar and account
GetDefaultCalendarAndAccount();
}
public void GetFolders(Outlook.MAPIFolder folder, Outlook.Application app)
{
if (folder.Folders.Count == 0)
{
if (folder.DefaultItemType == Outlook.OlItemType.olAppointmentItem)
{
StoreAndCalendar ci = new StoreAndCalendar();
Outlook.Account acc = GetAccountForFolder(folder, app);
if (acc != null)
{
if (!folder.FullFolderPath.Contains("Deleted"))
{
ci.Text = folder.Name + " - " + acc.DisplayName;
ci.Account = acc.DisplayName;
ci.Storename = acc.UserName;
ci.Value = folder.Name;
calendarSelector.Items.Add(ci);
}
}
}
}
else
{
if (folder.DefaultItemType == Outlook.OlItemType.olAppointmentItem)
{
StoreAndCalendar ci = new StoreAndCalendar();
Outlook.Account acc = GetAccountForFolder(folder, app);
if (acc != null)
{
if (!folder.FullFolderPath.Contains("Deleted"))
{
ci.Text = folder.Name + " - " + acc.DisplayName;
ci.Account = acc.DisplayName;
ci.Storename = acc.UserName;
ci.Value = folder.Name;
calendarSelector.Items.Add(ci);
}
}
}
foreach (Outlook.MAPIFolder subFolder in folder.Folders)
{
GetFolders(subFolder, app);
}
}
}
Outlook.Account GetAccountForFolder(Outlook.MAPIFolder folder, Outlook.Application app)
{
// Obtain the store on which the folder resides.
Outlook.Store store = folder.Store;
// Enumerate the accounts defined for the session.
foreach (Outlook.Account account in app.Session.Accounts)
{
// Match the DefaultStore.StoreID of the account
// with the Store.StoreID for the currect folder.
if (account.DeliveryStore.StoreID == store.StoreID)
{
// Return the account whose default delivery store
// matches the store of the given folder.
return account;
}
}
// No account matches, so return null.
return null;
}
public void GetDefaultCalendarAndAccount()
{
try
{
Outlook.Application OutlookApp = new Outlook.Application();
Outlook.NameSpace ns;
Outlook.MAPIFolder defaultfolder;
Outlook.Account defaultaccount;
ns = OutlookApp.Session;
ns.SendAndReceive(false);
defaultfolder = ns.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderCalendar);
defaultaccount = GetAccountForFolder(defaultfolder, OutlookApp);
String defaultaccandfold = defaultfolder.Name + " - " + defaultaccount.DisplayName;
int index = 0;
for (int i = 0; i < calendarSelector.Items.Count; i++)
{
string value = calendarSelector.GetItemText(calendarSelector.Items[i]);
if (value == defaultaccandfold)
{
calendarSelector.SelectedIndex = index;
}
index++;
}
}
catch { }
}
What is the best way of going through the accounts, and all of their subfolders, listing all the valid calendars?
Also, selecting the default calendar: is that the way it has to be done?
Thank you!

Answer 1

You're on target as to the best approach. But some suggestions:
There's no need to iterate through Accounts, just parse Stores
Don't process Stores for non-email Store objects, like SharePoint Lists and Internet Calendars (unless you want those kinds of Calendars)
Don't use foreach loops with the Outlook Object Model, use for loops so you can explicitly call Marshal.ReleaseComObject on every variable that references an Outlook object
Your call to NameSpace.SendAndReceive is probably unnecessary and could be causing some delays