/// <summary>
        /// Creates a banner add.
        /// </summary>
        /// <param name="add">The banner add.</param>
        /// <returns></returns>
        /// <exception cref="System.ArgumentException">Banner add is invalid.</exception>
        public int CreateBannerAdd(BannerAdd add)
        {
            //Validate banner add.
            if(add == null)
            {
                throw new ArgumentException("Banner add is invalid.");
            }

            //Add and save to the database.
            _context.BannerAdds.Add(add);
            _context.SaveChanges();

            //Return the new id.
            return add.Id;
        }
        /// <summary>
        /// Updates a banner add.
        /// </summary>
        /// <param name="add">The banner add.</param>
        public void UpdateBannerAdd(BannerAdd add)
        {
            BannerAdd addToUpdate = (from a
                                     in _context.BannerAdds
                                     where a.Id.Equals(add.Id)
                                     select a).FirstOrDefault();
            if (!string.IsNullOrEmpty(add.FileName))
            {
                addToUpdate.FileName = add.FileName;
            }
            addToUpdate.Name = add.Name;
            addToUpdate.RotationEnd = add.RotationEnd;
            addToUpdate.RotationStart = add.RotationStart;

            _context.SaveChanges();
        }