/// <summary>
        /// Updates the customer attribute
        /// </summary>
        /// <param name="customerAttribute">Customer attribute</param>
        public void UpdateCustomerAttribute(CustomerAttribute customerAttribute)
        {
            if (customerAttribute == null)
                throw new ArgumentNullException("customerAttribute");

            if (customerAttribute.CustomerId == 0)
                throw new NopException("Cannot insert attribute for non existing customer");

            customerAttribute.Key = CommonHelper.EnsureNotNull(customerAttribute.Key);
            customerAttribute.Key = CommonHelper.EnsureMaximumLength(customerAttribute.Key, 100);
            customerAttribute.Value = CommonHelper.EnsureNotNull(customerAttribute.Value);
            customerAttribute.Value = CommonHelper.EnsureMaximumLength(customerAttribute.Value, 1000);

            if (!_context.IsAttached(customerAttribute))
                _context.CustomerAttributes.Attach(customerAttribute);

            _context.SaveChanges();
        }
        /// <summary>
        /// Inserts a customer attribute
        /// </summary>
        /// <param name="customerAttribute">Customer attribute</param>
        public void InsertCustomerAttribute(CustomerAttribute customerAttribute)
        {
            if (customerAttribute == null)
                throw new ArgumentNullException("customerAttribute");

            if (customerAttribute.CustomerId == 0)
                throw new NopException("Cannot insert attribute for non existing customer");

            if (customerAttribute.Value == null)
                customerAttribute.Value = string.Empty;

            customerAttribute.Key = CommonHelper.EnsureNotNull(customerAttribute.Key);
            customerAttribute.Key = CommonHelper.EnsureMaximumLength(customerAttribute.Key, 100);
            customerAttribute.Value = CommonHelper.EnsureNotNull(customerAttribute.Value);
            customerAttribute.Value = CommonHelper.EnsureMaximumLength(customerAttribute.Value, 1000);

            _context.CustomerAttributes.AddObject(customerAttribute);
            _context.SaveChanges();
        }