CODEWITHSUNDEEP
c#sharepointsharepoint-2010attachmentcaml
Toon Casteele
Toon Casteele

Reputation: 2579

Lists.AddAttachment throws object reference error

I'm trying to add an attachment to a list item I just created on a sharepoint server using CAML. The code below is simplified (for example the path is normally a variable and the 2nd field (the item id, here 16847) is normally the id I get back from my insert statement in CAML).

This is my code:

String desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
String savePath = desktopPath + @"\" + "tutorials.txt";
byte[] data = GetData(savePath);
lists.AddAttachment("Tasks", "16847", "tutorials.txt", data);

I'm getting this error:

Unable to update the security according your changes. The following exception occurred during ItemUpdating: Object reference not set to an instance of an object. See Event Viewer for more information.0x81020089

getdata is a method which converts the file on my desktop to a byte[]. data is not empty and it looks okay.

Other than that Tasks is the List needed and 16847 is the task id in which to add the attachment.

Most of the info I can find is about a different error: the index out of range exception (like on the msdn page: http://msdn.microsoft.com/en-us/library/lists.lists.addattachment(v=office.12).aspx).

I've also tried a http put (unauthorized access, obviously) and the copy service (I can post this code if we can't find the solution to the simpler way above).

Can anyone tell me what is wrong?

EDIT 1:

private dcp.Lists lists = new dcp.Lists(); 
lists.Credentials = System.Net.CredentialCache.DefaultCredentials; 
lists.Url = Values.SERVERADDRESS + "/_vti_bin/lists.asmx";

This initializes the connection to our web service. It works perfectly fine for updates, inserts...

GetData code:

private byte[] GetData(String savePath)
    {
        byte[] contents;
        using (FileStream fStream = File.OpenRead(savePath))
        {
            contents = new byte[fStream.Length];
            sFileName = fStream.Name;
            fStream.Read(contents, 0, Convert.ToInt32(fStream.Length));
        }
        return contents;
    }

EDIT 2:

Note that the following does work (I get a correct list of existing attachments from the task):

XmlNode ndAttach = lists.GetAttachmentCollection("Tasks", "16847");

MessageBox.Show(ndAttach.OuterXml);

And the following doesn't (same error as for the AddAttachment method):

lists.DeleteAttachment("Tasks", "16847", ndAttach.ChildNodes[0].InnerText);

Whereas I'm quite certain this should work since it does exactly the same as the example code on msdn: http://msdn.microsoft.com/en-us/library/lists.lists.deleteattachment(v=office.12).aspx

Upvotes: 4

Views: 781

Answers (1)

Toon Casteele
Toon Casteele

Reputation: 2579

The code above is fine, the error occured on our server. When adding an attachment, no contenttype is given in the xml. This was programmed to throw an error because we've always used this method to update and add new items. So we removed the contenttype out of the underlying code and it works like a charm.

Upvotes: 2

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