/// <summary>
        /// Determines of any entities exist matching the specified filter.
        /// </summary>
        /// <param name="filter">The filter.</param>
        /// <param name="applyDefaultFilters">if set to <c>true</c> [apply default filters].</param>
        /// <returns>Task&lt;System.Boolean&gt;.</returns>
        public virtual async Task <bool> Exists(Expression <Func <TEntity, bool> > filter, bool applyDefaultFilters = true)
        {
            if (applyDefaultFilters)
            {
                filter = ApplyDefaultFilters(filter);
            }

            return(await _repository.Exists(filter));
        }