Sharepoint Online：使用客户端对象模型将列表项的附件复制到新项目

Question

我想从一个列表项（在 ItemCreated 事件中）读取附件到另一个新的 ListItem。如何使用 客户端对象模型 做到这一点？我发现的只是服务器端代码...

另一个问题：当我删除列表项时附件是否也被删除了，还是它们仍然存在于服务器上？

Answer 1

我明白了！以下代码对我有用：

private static void NewTryToAttachFiles(ClientContext ctx, Web web, List fromList, ListItem fromItem, List toList, ListItem toItem)
    {
        string src = string.Format("{0}/lists/{1}/Attachments/{2}", web.Url, fromList.Title, fromItem.Id);

        Folder attachmentsFolder = web.GetFolderByServerRelativeUrl(src);
        web.Context.Load(attachmentsFolder);
        FileCollection attachments = attachmentsFolder.Files;

        web.Context.Load(attachments);
        web.Context.ExecuteQuery();

        if(attachments.Count > 0)
        {
            foreach (File attachment in attachments)
            {
                // FileInformation fileInfo = File.OpenBinaryDirect(ctx, attachment.ServerRelativeUrl);

                ctx.Load(toItem);
                var clientResultStream = attachment.OpenBinaryStream();
                ctx.ExecuteQuery();
                var stream = clientResultStream.Value;



                AttachmentCreationInformation attachFileInfo = new AttachmentCreationInformation();
                Byte[] buffer = new Byte[attachment.Length];
                int bytesRead = stream.Read(buffer, 0, buffer.Length);
                System.IO.MemoryStream stream2 = new System.IO.MemoryStream(buffer);
                attachFileInfo.ContentStream = stream2;
                attachFileInfo.FileName = attachment.Name;

                Attachment a = toItem.AttachmentFiles.Add(attachFileInfo);
                ctx.Load(a);
                web.Context.ExecuteQuery();
                stream2.Close();
            }
        }
        ctx.Load(toItem);
        ctx.ExecuteQuery();
    }

它将一个列表项（fromItem）的附件复制到新项！