Posts Tagged ‘C#’

An Outlook Conversation

Gordon  24 Feb, 2009  1 Comment

One of the things that I had to do in Outlook this week was to determine if an outlook MailItem is part of a conversation. 

After much googlework, I discovered  two properties on the Outlook MailItem – ConversationIndex and ConversationTopic.

To determine if an Outlook Item is part of a Conversation, you need to look at the first 22 bytes of the hex string reported for ConversationIndex. If they are the same, then the message is part of the same conversation. 
 

using Microsoft.Office.Interop.Outlook;      
  1.  
  2. public static bool SameConversation(MailItem item1, MailItem item2)
  3.  
  4.       {
  5.        return item1.ConversationIndex.Substring(0, 22) ==
  6.        item2.ConversationIndex.Substring(0, 22);
  7.       }

That’s all well and good, but note that this property is somewhat unreliable. For starters, in versions of outlook prior to 2003, it returned binary data, instead of a hex string (but if you’re working with versions of Outlook prior to 2003, you probably have other problems…) The other reason this property is unreliable is because it is set by the client – Outlook appends a 5 byte timestamp to the ConversationIndex when you reply. Which is cool, as long as you reply through Outlook.

But – our Infovark mail server is hosted by Google, and I occasionally use the gmail web client to reply to mail,  instead of Outlook. For these conversations, when the replies were eventually retrieved into Outlook via IMAP, they ended up with unique conversationindexes, and so I couldn’t identfy them as being part of the same conversation.

In these cases, that’s where the ConversationTopic Property can help give you a clue. The ConversationTopic is the normalized subject of the message, that is, the subject without all the prefix strings (“Re:Re:” etc.) By comparing ConversationTopics, you can usually piece together the conversation, even if the ConversationIndex is not correct.

Converting IEnumerable to a Comma-Delimited String

Dean  2 Sep, 2008  1 Comment

I’m not sure whether it’s the fastest way to convert an enumerable collection of longs or ints to a comma-delimited list in C#, but it might be the shortest.

  1. IEnumerable<long> ids = new long[]{1,3,4,5};
  2. string delimitedIds = string.Join(",", ids.Select(x => x.ToString()).ToArray());

If you need a LINQ-free version for backward compatibility, check out Missing Functions on IEnumerable on Steve Cooper’s blog.

Handling COM Error Codes

Gordon  20 Aug, 2008  No Comment

Sometimes COM Objects return a HRESULT that is outside of the bounds of a C#  integer.

Unfortunately, the only way to correctly handle a COM Exception in .NET is to use the ComException Class. But if the HRESULT isn’t an Int, and the ErrorCode Property on the ComException class is an Int, how are you supposed to ever be able to catch that specific HRESULT?

Fear not! Here’s how to handle a COM ErrorCode that can’t be converted to an Int (in this example, it’s unsigned)

try
  1.  {
  2.   _PropertyHandler.Open(filePath, false, dsoFileOpenOptions.dsoOptionDefault);
  3.  }
  4.  catch (COMException comEx)
  5.  {
  6.   if (comEx.ErrorCode == unchecked((int)0×800300FC))
  7.    {
  8.     throw new FileNotFoundException("Could not find file:");
  9.    }
  10.  }

The magic happens in the ‘unchecked’ statement – which tells the compiler not to perform the overflow-checking context for integral-type arithmetic operations and conversions.

More on the Unchecked Operator over on MSDN.