SharePoint 2007, how to check if a folder exists in a document library

Question

I am accessing SharePoint via its web services... Which are a bit limited, as a result I have turned to WebDav to perform some create folder functionality...

I have a document library, and I am about to create a folder using webdav, but I can't find any documentation on the internet or anywhere else on how to check if a folder already exists using webdav, so is there a way to check if a folder exists in a document library in SharePoint, any hack and slash methods welcome!

Bodine

Answer 1

Somehow, I don't get your question. First sentence states you are using web service (I'd normally understand it as the SOAP web services provided by SharePoint). The next one says you are using WebDAV which is a completely different protocol.

So, WebDAV is the protocol "Windows Explorer" uses to access SharePoint, if you open it it "Explorer mode". Since all these requests are actually HTTP requests, you can spy on them, using the "Fiddler" tool.

I believe, before opening a folder, Windows Explorer tries to query sharepoint, if such folder exists. If I try to open an unexistant path \\mysrv\sites\myweb\mylib\notthere (but \\mysrv\sites\myweb\mylib is an existing document library!) thru windows explorer, the last HTTP call I see is:

PROPFIND /sites/myweb/mylib HTTP/1.1
User-Agent: Microsoft-WebDAV-MiniRedir/6.1.7600
Depth: 1
translate: f

Where SharePoint responds with: a list of subfolders and pages in this folder (very long XML, but it contains items like this):

<D:multistatus
    xmlns:D="DAV:"
    xmlns:Office="urn:schemas-microsoft-com:office:office"
    xmlns:Repl="http://schemas.microsoft.com/repl/"
    xmlns:Z="urn:schemas-microsoft-com:">
  <D:response>
    <D:href>http://sites/myweb/mylib</D:href>
    <D:propstat>
      <D:prop>
        <D:displayname>mylib</D:displayname>
        <D:lockdiscovery/>
        <D:supportedlock/>
        <D:isFolder>t</D:isFolder>
        <D:iscollection>1</D:iscollection>
        <D:ishidden>0</D:ishidden>
        <D:getcontenttype>application/octet-stream</D:getcontenttype>
        <D:getcontentlength>0</D:getcontentlength>
        <D:resourcetype>
          <D:collection/>
        </D:resourcetype>
        <Repl:authoritative-directory>t</Repl:authoritative-directory>
        <D:getlastmodified>2009-12-07T09:07:19Z</D:getlastmodified>
        <D:creationdate>2009-11-06T13:30:26Z</D:creationdate>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
  <!---List of other <D:response> elements -->
</D:multistatus>

If the contained element is a folder, it must have "D:isFolder" value "t". This way you can find, if the parent folder contains the folder you are going to create.

EDIT: created a small c# sample which first reads the result stream and then parses the result a bit. You need to make it better, to see if the list contains the folders you need or not.

System.Net.HttpWebRequest oReq;
string sUrl = "http://yoursite/sites/somesite/DocumentLibrary";
oReq = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(sUrl);

oReq.Method = "PROPFIND";
oReq.Credentials = System.Net.CredentialCache.DefaultCredentials;
oReq.AllowAutoRedirect = true;
oReq.UserAgent = "Microsoft-WebDAV-MiniRedir/6.1.7600";

//this causes all of the items to be enumerated, 
//if it is 0, only the folder itself is returned in the response
oReq.Headers["Depth"] = "1";
oReq.Headers["translate"] = "f";
System.IO.StreamWriter oRequest =
        new System.IO.StreamWriter(oReq.GetRequestStream());
oRequest.WriteLine();
oRequest.Close();
System.IO.StreamReader oResponse =
        new System.IO.StreamReader(oReq.GetResponse().GetResponseStream());
string sResponse = oResponse.ReadToEnd();
oResponse.Close();

//done with the webclient stuff, check the results

System.Xml.XmlDocument oMyDoc = new System.Xml.XmlDocument();
oMyDoc.LoadXml(sResponse);
System.Xml.XmlNamespaceManager oNsMgr =
        new System.Xml.XmlNamespaceManager(oMyDoc.NameTable);
oNsMgr.AddNamespace("D", "DAV:");

System.Xml.XmlNodeList oAllResponses =
        oMyDoc.SelectNodes(".//D:multistatus/D:response", oNsMgr);

foreach (System.Xml.XmlNode oNode in oAllResponses)
{
    Console.WriteLine("Name: " + 
                      oNode.SelectSingleNode("./D:propstat/D:prop/D:displayname",
                      oNsMgr).InnerText);

    if (oNode.SelectNodes("./D:propstat/D:prop/D:isFolder", oNsMgr).Count > 0)
    {
        Console.WriteLine("Is folder: " + 
                oNode.SelectSingleNode("./D:propstat/D:prop/D:isFolder", 
                oNsMgr).InnerText);
    }
    else
    {
        Console.WriteLine("Is folder: f");
    }
    Console.WriteLine();
}

Schaab

Can you provide a C# sample on how to use this information in a practical way? – Bodine

Thank you so much naivists, you got it just on the mark. awesome code, thanks again!!! – Bodine

Welcome :-) It was an interesting investigation for me too, since I had never used WebDAV to access SharePoint sites. – Schaab

One last question... if I am passing the URL to a folder, and set the depth to one... then surely if the response is successful then the folder exists... and I don't need to iterate through the XML node collection right? – Bodine

Yes, I thought about that just some minutes after I posted my code here. I think it must be the way you're describing it, but I did not check. It might as well be possible that SharePoint returns a 404 error in case the folder is not there (since the resource whose properties you're trying to read does not exist) – Schaab

I tested it - SharePoint does return the 404, but its not that simple... seems Propfind is the only reliable method that works. I tried GET and HEAD, and both gave strange results on differant MOSS resources. – Bodine

Also, I got good responses on how to improve the XPath query to find the isFolder match: #2012034 – Schaab

-1: You're missing using statements for your StreamReader/Writer. Also, for larger documents, you might get better performance using XmlDocument.Load instead of reading the whole string in first. – Gourde

Answer 2

YOu don;t need to, if it already exists, trying to create a new folder with that name will "silently" return the already existing folder.

Firebrat