Too many automatic redirections were attempted

Question

I am having some trouble when trying to us the SharePoint Client Object Model against a SharePoint 2013 installation. I am attempting to write some code which will allow both the upload and download of a file into a Document Library.

I have got the Upload part to work perfectly, using:

using (var context = new ClientContext(this.appSettingsProvider.SharePointServerUrl))
{
    try
    {
        using (var fs = new FileStream(filePath, FileMode.Open))
        {
            Microsoft.SharePoint.Client.File.SaveBinaryDirect(
                        context,
                        string.Format("/{0}/{1}", documentFolder, fileInfo.Name),
                        fs,
                        false);
        }

        return true;
    }
    catch (Exception ex)
    {
        this.logger.Error(ex);
    }

    return false;
    }
}

Where filePath and documentFolder are passed into my function.

However, when it comes to deleting the document, I am using the following code which I found here:

Delete Item in Document Library using Client Object Model?

var returnValue = false;

try
{
    using (var clientContext = new ClientContext(this.appSettingsProvider.SharePointServerUrl))
    {
        var sharePointList = clientContext.Web.Lists.GetByTitle(documentFolder);
        var query = new CamlQuery();
        query.ViewXml = "<View>" + "<Query>"
                                + "<Where><Eq><FieldRef Name='FileLeafRef'/><Value Type='File'>" + filePath
                                + "</Value></Eq></Where>" + "</Query>" + "</View>";

        // execute the query
        var listItems = sharePointList.GetItems(query);
        clientContext.Load(listItems);
        clientContext.ExecuteQuery();

        foreach (var listitem in listItems)
        {
            listitem.DeleteObject();
            clientContext.ExecuteQuery();
            returnValue = true;
        }
    }
}
catch (Exception ex)
{
    this.logger.Error(ex);
}

return returnValue;

When I try to run this code, I keep getting back the exception:

Too many automatic redirections were attempted.

Has anyone run into this before? Any ideas on how to correct this? I have found references to a requirement to capture the cookies that are being used in the request, but I couldn't find any clear way on how to implement this.

I ran into a similar issue when I tried to use this code:

https://stackoverflow.com/a/8011028/671491

For checking whether a item already exists in the document library. The thing they have in common is the use of ExecuteQuery.

Any help would be greatly appreciated!

Answer 1

You are committing one Cardinal Sin of .NET programming; you are deleting items of a collection in a foreach loop. When you delete an item in a loop like this, you are changing the collection that's being iterated, but the foreach loop still attempts to iterate as if the collection was still in its original state, and eventually the enumerator get out of whack and an exception is thrown.

The by-the-book way to delete items in a collection is to use a backwards for-loop, like this:

for (int i = listItems.Count -1; i  <= 0; i--)
{
   listitems[i].DeleteObject();
}
clientContext.ExecuteQuery();
returnValue = true;

I would also move the ExecuteQuery() line outside the loop. You only need to call it and set the return value once.