private bool GetAndUpdateDocuments()
{
    // Create an instance of the Tree provider first
    TreeProvider tree = new TreeProvider(CMSContext.CurrentUser);

    // Fill dataset with documents
    DataSet documents = tree.SelectNodes(CMSContext.CurrentSiteName, "/API-Example/%", "en-us", false, "CMS.MenuItem");

    if (!DataHelper.DataSourceIsEmpty(documents))
    {
        // Loop through all documents
        foreach (DataRow documentRow in documents.Tables[0].Rows)
        {
            // Create a new Tree node from the data row
            TreeNode editDocument = TreeNode.New(documentRow, "CMS.MenuItem", tree);

            string newName = editDocument.DocumentName.ToLower();

            // Change coupled data
            editDocument.SetValue("MenuItemName", newName);
            // Change document data
            editDocument.DocumentName = newName;

            // Save to database
            editDocument.Update();               
        }

        return true;
    }

    return false;
}