Sharepoint Online:使用客户端对象模型将列表项的附件复制到新项 [英] Sharepoint Online: Copy attachment of list item to a new item using Client object model

问题描述

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

I want to read the attachments from one list item (in ItemCreated event) to another, new ListItem. How can I do this with the Client Object Model? All I found is server-side code...

另一个问题:当我删除列表项时，附件也被删除了吗?还是服务器上仍然存在这些附件?

Another question: Are the attachments also deleted when I delete a list item or are they still existing on the server?

推荐答案

我明白了！以下代码对我有用:

I got it! The following code worked for me:

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！

It copies the attachments of one list item (fromItem) to the new item!

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