如果不存在，则创建一个SharePoint文件夹。

Question

如果在SharePoint文档库中不存在某个文件夹，则我需要创建该文件夹，然后将文件上传至其中。 以下是我正在使用的代码：

public static bool FolderExists(Web web, string listTitle, string folderUrl)
{
    var list = web.Lists.GetByTitle(listTitle);
    var folders = list.GetItems(CamlQuery.CreateAllFoldersQuery());
    web.Context.Load(list.RootFolder);
    web.Context.Load(folders);
    web.Context.ExecuteQuery();
    var folderRelativeUrl = string.Format("/{0}/{1}", list.RootFolder.ServerRelativeUrl, folderUrl);
    return Enumerable.Any(folders, folderItem => (string)folderItem["FileRef"] == folderRelativeUrl);
}

private static void CreateFolder(Web web, string listTitle, string folderName)
{
    var list = web.Lists.GetByTitle(listTitle);
    var folderCreateInfo = new ListItemCreationInformation
    {
        UnderlyingObjectType = FileSystemObjectType.Folder,
        LeafName = folderName
    };
    var folderItem = list.AddItem(folderCreateInfo);
    folderItem.Update();
    web.Context.ExecuteQuery();
}

public void UploadFile(string CourseId, string path)
{
    string libraryName = "Documents";
    using (ClientContext clientContext = GetContextObject())
    {
        // if a folder doesn't exists, create it
        if (!FolderExists(clientContext.Web, libraryName, CourseId))
        {
            CreateFolder(clientContext.Web, libraryName, CourseId);

        }

        // if exists, upload input file in Documents/FolderName given by CourseId
        Web web = clientContext.Web;
        List list3 = clientContext.Web.Lists.GetByTitle("Documents");
        clientContext.Load(list3.RootFolder);
        clientContext.ExecuteQuery();
        using (FileStream fileStream = new FileStream(path, FileMode.Open))
        {
            string ext = Path.GetExtension(fileStream.Name);
            Microsoft.SharePoint.Client.File.SaveBinaryDirect(clientContext, list3.RootFolder.ServerRelativeUrl.ToString() + "/" + CourseId + "/" + path.Split('\\').Last(), fileStream, true);
        }

    }

}

问题如下：这些函数很好用，但如果文件夹已经存在，则尝试再次创建它会导致异常，而应该只上传文件到“CourseId”文件夹并跳过其创建。我该如何解决？

- Dan

Answer 1

尝试以下代码，它可以帮助您检查SharePoint文件夹是否存在。

 using Microsoft.SharePoint.Client;

 namespace SharePoint.Client.Extensions
 {
 public static class WebExtensions
 {
    public static bool TryGetFileByServerRelativeUrl(this Web web, string serverRelativeUrl, out File file)
    {
        var ctx = web.Context;
        try
        {
            file = web.GetFileByServerRelativeUrl(serverRelativeUrl);
            ctx.Load(file);
            ctx.ExecuteQuery();
            return true;
        }
        catch (ServerException ex)
        {
            if (ex.ServerErrorTypeName == "System.IO.FileNotFoundException")
            {
                file = null;
                return false;
            }
            throw;
        }
     }
  }
}

- Ethiraj

---

谢谢！虽然它不能帮助我，但这是一个有用的答案。 - Dan

Answer 2

在FolderExists方法中更改以下代码行

var folderRelativeUrl = string.Format("/{0}/{1}", list.RootFolder.ServerRelativeUrl, folderUrl);

to

var folderRelativeUrl = string.Format("{0}/{1}", list.RootFolder.ServerRelativeUrl, folderUrl);

注意：将“/{0}/{1}”修改为“{0}/{1}”。

- LZ_MSFT