Attach document in custom list item using Client Object Model?

Question

How to attach file in specific Custom list item in SharePoint online using Client Object model?

Any help is appreciated! Thanks!

Answer 1

using (ClientContext context = new ClientContext("http://SharepointURL/"))
{
    try
    {


        Web web = context.Web;

        FileCreationInformation newFile = new FileCreationInformation();
        newFile.Content = System.IO.File.ReadAllBytes(@"C:\test.txt");
        newFile.Url = "test.txt";

        List docs = web.Lists.GetByTitle("CustomList");
    ListItem item = docs.GetItemById(ID);

    var attInfo = new AttachmentCreationInformation();
    attInfo.FileName = mFile.Name;
    attInfo.ContentStream = new MemoryStream(System.IO.File.ReadAllBytes("streamFile"));

    Attachment att = item.AttachmentFiles.Add(attInfo); //Add to File

    context.Load(att);
    context.ExecuteQuery();
    Console.WriteLine("done");


    }
    catch (Exception ex)
    {
        throw ex;
    }
}

Hope this code helps you to attach file to list item.