How can I retrieve a list item's attachments, or at least the paths to the attachments from SharePoint via the Silverlight Client Object Model?

Question

I've got a SharePoint site that I'm putting a Silverlight frontend on using the Silverlight Client Object Model. 我需要提取數據的列表之一有附件。 我需要找到一種方法來列出這些附件，但我似乎找不到這樣做的方法。

ListItem 上有一個“附件”字段，但它只是一個 boolean 說明附件是否存在。

I've seen plenty of examples of this using SPListItem, but how would I go about doing this using the Silverlight Client Object Model instead?

Answer 1

我也遇到了這個問題，在 ScottyG30 的回答和在這個線程上的回答的幫助下，我寫了一個 function 來從 ListItem 中檢索附件：

// this method needs to be executed in background thread
public String[] GetAttachments(ClientContext ctx, List list, ListItem item)
{
    // these properties can be loaded in advance, outside of this method
    ctx.Load(list, l => l.RootFolder.ServerRelativeUrl);
    ctx.Load(ctx.Site, s=>s.Url);
    ctx.ExecuteQuery();

    // get the item's attachments folder 
    Folder attFolder = ctx.Web.GetFolderByServerRelativeUrl( list.RootFolder.ServerRelativeUrl + "/Attachments/" + item.Id);
    FileCollection files = attFolder.Files;
    // I needed only urls, so I am loading just them
    ctx.Load(files, fs => fs.Include(f => f.ServerRelativeUrl));
    ctx.ExecuteQuery();

    // now you have collection of files
    return (from file in files select ctx.Site.Url + file.ServerRelativeUrl).ToArray();
}

雖然這對我有用，但當您需要大型列表中所有項目的附件（url）時（每個項目都在executing query ），它似乎不是最佳解決方案。

Answer 2

ClientContext spContext = ClientContext.Current;
File.OpenBinaryDirect(spContext, spContext.Web.ServerRelativeUrl + "/lists/[ListName]/Attachments/[ItemID]/[File Name]", (w, f) =>
        {
            var foo = f.Stream;

        }, (q, w) => { 
            handler(this, new Exception(w.Message)); 
        });