SharePoint 2010 - Client Object Model - Add attachment to ListItem

Question

I have a SharePoint List to which I\'m adding new ListItems using the Client Object Model. Adding ListItems is not a problem and works great.

Now I want to add att

Answer 1

With Sharepoint 2010 there was no way to upload a first attachment to a list item using the COM. The recommendation was to use the Lists web service inmstead.

With Sharepoint 2013 it works.

AttachmentCreationInformation newAtt = new AttachmentCreationInformation();
newAtt.FileName = "myAttachment.txt";
// create a file stream
string fileContent = "This file is was ubloaded by client object meodel ";
System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
byte[] buffer = enc.GetBytes(fileContent);
newAtt.ContentStream = new MemoryStream(buffer);

// att new item or get existing one
ListItem itm = list.GetItemById(itemId);
ctx.Load(itm);   
// do not execute query, otherwise a "version conflict" exception is rised, but the file         is uploaded
// add file to attachment collection
newAtt.ContentStream = new MemoryStream(buffer);
itm.AttachmentFiles.Add(newAtt); 
AttachmentCollection attachments = itm.AttachmentFiles;
ctx.Load(attachments);
ctx.ExecuteQuery(); 
// see all attachments for list item
// this snippet works if the list item has no attachments

This method is used in http://www.mailtosharepoint.net/