Develop Reference

Microsoft Office Interop Outlook w/ C# - Why does Items.GetNext() return null?

I'm trying to fetch attachments from a particular folder in Outlook 2010 in a C# Windows Forms app. I have a class called MailInbox that contains the Outlook namespace, inbox, and message objects.
Here is the code for that class and its methods:
public class mailInbox
{
//declare needed variables for outlook office interop
public Outlook.Application oApp = new Outlook.Application();
//public Outlook.MAPIFolder oInbox;
public Outlook.MAPIFolder idFolder;
public Outlook.NameSpace oNS;
public Outlook.Items oItems;
public Outlook.MailItem oMsg;
public Outlook.MAPIFolder subFolder;
public string subFolderName;
public mailInbox()
{
//read the subfoldername from a text file
using (StreamReader subFolderNameRead = new StreamReader(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + #"\SuperVerify\config\subfoldername.txt"))
{
subFolderName = subFolderNameRead.ReadLine().Trim();
}
oNS = oApp.GetNamespace("mapi");
//oInbox = oNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox);
idFolder = oNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox).Folders[subFolderName]; // use the subFolderName string, read from the config text file, to get the folder from outlook
oItems = idFolder.Items;
//oMsg = (Outlook.MailItem)oItems.GetNext();
}
public void FetchEmail() // fetches the next email in the inbox and saves the attachments to the superverify folder
{
oNS.Logon(Missing.Value, Missing.Value, false, true); //login using default profile. This might need to be changed.
oMsg = (Outlook.MailItem) oItems.GetNext(); //fetch the next mail item in the inbox
if(oMsg.Attachments.Count > 0) // make sure message contains attachments **This is where the error occurs**
{
for (int i =0; i< oMsg.Attachments.Count; i++)
{
oMsg.Attachments[i].SaveAsFile(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + #"\SuperVerify\images\" + oMsg.Attachments[i].FileName); //save each attachment to the specified folder
}
} else //if no attachments, display error
{
MessageBox.Show("The inbox folder has no messages.", "TB ID Verification Tool", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
}
public void changeSubFolderName(string newSubFolderName)
{
subFolderName = newSubFolderName;
}
}
When I click the button that invokes the FetchEmail method, I get the error
System.NullReferenceException: 'Object reference not set to an instance of an object.'
oMsg was null. I thought that
public Outlook.MailItem oMsg;
instantiated the object and that
oMsg = (Outlook.MailItem) oItems.GetNext();
assigned it an Outlook MailItem, but it seems I don't understand what's going on here.

From the documentation which curiously references VB.NET's Nothing instead of null,
It returns Nothing if no next object exists, for example, if already positioned at the end of the collection.To ensure correct operation of the GetFirst, GetLast, GetNext, and GetPrevious methods in a large collection, call GetFirst before calling GetNext on that collection, and call GetLast before calling GetPrevious. To ensure that you are always making the calls on the same collection, create an explicit variable that refers to that collection before entering the loop.
So GetNext will return null if you're at the end of the folder. You'd have to check it for null before attempting to use it.
You can also use oItems.Count to determine that there are no items when you initially access the folder's items. But if Count is one or more you'd still have to check for null, because you're dealing with a collection that can change. Hypothetically someone could remove items from the folder while you're reading it, so you can't get the count up front and then rely on it.

Error when opening some Outlook MailItems with GetItemFromID using EntryID from Outlook Spy

When I Use OutlookSpy to get the EntryIDs from MailItems in a particular folder and supply them to the following code:
Outlook.Application myApp = new Outlook.ApplicationClass();
Outlook.NameSpace mapiNameSpace = myApp.GetNamespace("MAPI");
try
{
object obj = mapiNameSpace.GetItemFromID(sEntryID);
if (obj is Outlook.MailItem)
{
var getItem = (Outlook.MailItem)mapiNameSpace.GetItemFromID(sEntryID);
getItem.Display();
}
}
catch (Exception Ex)
{
Global.Common.LogError("Error accessing MailItem", Ex, "EntryID " + sEntryID + " not found in " + sFolder, "Warning");
}
I get unknown messaging errors for some EntryID values and successful display of the messages in Outlook with others. Can anyone suggest what attributes the MailItems might have which will affect whether I can display them successfully using GetItemFromID or any other method of displaying all messages by EntryID reliably?

Was the message store where the message resides touched in the active Outlook session? The way MAPI providers work, when a provider is loaded by MAPI, it registers the set of entry id guids (bytes 5-20 in the entry id) that it will handle. If the particular PST store has not been touched in the current session, MAPI does not know anything about its entry ids.
You can either access all the stores in the current session first (to make sure MAPI knows about their entry ids) or use the store entry id (second parameter, optional) when calling GetItemFromId - this way Outlook will open the store first, then ask the store to open the item. You can also call Namespace.AddStore / AddStoreEx to load the given PST file if it is not already in the current profile.
You might also want to log the exception details (Ex.Message) in your exception handler.

Thanks to all the respondents - this explains why sometimes particular messages would open and sometimes they would not. By getting the StoreId using the following code:
Outlook.Application myApp = new Outlook.ApplicationClass();
Outlook.NameSpace mapiNameSpace = myApp.GetNamespace("MAPI");
Object oStoreID = Common.GetFolder(myApp, sFolder).StoreID;
try
{
object obj = mapiNameSpace.GetItemFromID(sEntryID,oStoreID);
if (obj is Outlook.MailItem)
{
Outlook.MailItem getItem = (Outlook.MailItem)mapiNameSpace.GetItemFromID(sEntryID,oStoreID);
getItem.Display();
}
}
Where
public static Outlook.Folder GetFolder(Outlook.Application App, string folderPath)
{
Outlook.Folder folder;
string backslash = #"\";
try
{
if (folderPath.StartsWith(#"\\"))
{
folderPath = folderPath.Remove(0, 2);
}
String[] folders =
folderPath.Split(backslash.ToCharArray());
folder =
App.Session.Folders[folders[0]]
as Outlook.Folder;
if (folder != null)
{
for (int i = 1; i <= folders.GetUpperBound(0); i++)
{
Outlook.Folders subFolders = folder.Folders;
folder = subFolders[folders[i]]
as Outlook.Folder;
if (folder == null)
{
return null;
}
}
}
return folder;
}
catch { return null; }
}
All MailItems now display in Outlook.

I'll just throw this in here for posterity-- Outlook 2002 requires that the entry ID supplied to GetItemFromID use upper-case hex characters.

Empty out file on different PCs C#.NET Add-in Outlook

I have the next problem. I've written the solution for MS Outlook 2010 that creates email summary and write it down to an Excel file(.xls) The problem is that on my PC and several others it works correctly but when I sent it to customers, they said that it creates summary only for inbox folder on some PCs and on others it doesn't work at all.
I've also created the possibility to choose the folder to get the emails but the problem left. I'll provide a code snippet of the function choosing folder and getting the list of emails. I save emails in List in private field of my class.
Take a look on this func and please help to get out what is wrong. Thanks.
public void GetTheArrayOfEmails(DateTime startDate, DateTime finishDate)
{
try
{
Outlook.Application oApp = new Outlook.Application();
Outlook.NameSpace oNs = oApp.GetNamespace("mapi");
oNs.Logon(Missing.Value, Missing.Value, false, false);
//Outlook.MAPIFolder folder = oApp.Session.PickFolder();
foreach (Outlook.MailItem oMsg in oApp.Session.PickFolder().Items)
{
if (oMsg.ReceivedTime.ToUniversalTime() > startDate.ToUniversalTime() &&
oMsg.ReceivedTime.ToUniversalTime() < finishDate.ToUniversalTime())
{
MailList.Add(oMsg);
}
}
oNs.Logoff();
releaseObject(oNs);
releaseObject(oApp);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
UPD: Fixed the problem. I missed cast. And tried to cast items which are not of MailItem interface.

How to retrieve the Outlook folder of a mail item (Outlook.MailItem)?

I am getting my default inbox folder via inboxFolder = Globals.ThisAddIn.Application.Session.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox
Elsewhere in my code, I begin doing a foreach loop to extract specific information I want from these MailItems
foreach (var item in this.inboxFolder.Items)
{
Outlook.MailItem mailItem = (Outlook.MailItem)item;
//.... doing stuff here
string SenderEmail = mailItem.SenderEmailAddress;
string SenderName = mailItem.SenderName;
string FolderLocation = mailItem.???; //how to retrieve folder location?
//.... more stuff here
}
For example: A user may have created a subfolder called 'Test' shown below.

Thank you for the pointer guys. However I was having some trouble implementing the same initially. Here is how I solved it, just in case if some one faces the same issue.
Outlook.MAPIFolder parentFolder = mailItemToDelete.Parent as Outlook.MAPIFolder;
string FolderLocation = parentFolder.FolderPath;
The Parent object is dynamic and hence was causing issue.

Do you mean folder path? Use MAPIFolder.FullFolderPath. Or MAPIFoldert.Name if you only need the name.
Also keep in mind that the value will be the same for all items in the folder, so there is no reason to evaluate it on each step of the loop.

Adding a folder to a pst file from outlook in c#

I have been trying to find a way to add a folder to a pst file from c#
I have tried a whole bunch of code to try and get this to work and this is the one that seems to be most likly to be correct (as it is whats on the MSDN) but still does not work
Main {
Outlook._Application OutlookObject = new Outlook.Application();
Outlook.Store NewPst = null;
// create the pst file
string pstlocation = "C:\\Users\\Test\\Desktop\\PST\\Test.pst";
try
{
OutlookObject.Session.AddStore(pstlocation);
foreach (Outlook.Store store in OutlookObject.Session.Stores)
{
if (store.FilePath == pstlocation)
{
// now have a referance to the new pst file
NewPst = store;
Console.WriteLine("The Pst has been created");
}
}
}
catch
{ }
// create a folder or subfoler in pst
Outlook.MAPIFolder NewFolder;
NewFolder = NewPst.Session.Folders.Add("New Test Folder", Type.Missing);
}
This code creates a new PST File and then trys to add a folder to it however the last line of code:
New NewFolder = NewPst.Session.Folders.Add("New Test Folder", Type.Missing);
Gets the error "The operation failed." and "Invalid Cast Exception" can some one point out what i am doing wrong
Thanks in advance

You need to use Store.GetRootFolder() to get a handle to the root folder of that store (not Store.Session). So you would use:
// create a folder or subfolder in pst
Outlook.MAPIFolder pstRootFolder = NewPst.GetRootFolder();
Outlook.MAPIFolder NewFolder = pstRootFolder.Folders.Add("New Test Folder");
I recommend bookmarking both of the following: The PIA documentation isn't always complete, so it's worth checking out the COM documentation as well for complete class and member info.
(.NET): Outlook 2007 Primary Interop Assembly Reference
(COM): Outlook Object Model Reference