csharp 查询选项V6

Posted 2021-05-12

public class QueryOption<T> : IQueryOption<T> where T:class
    {
        private readonly IQueryable<T> _queryable;

        public QueryOption(IQueryable<T> queryable)
        {
            _queryable = queryable;
        }
        internal List<Expression<Func<T, object>>> EagerLoads { get; set; }
        internal Expression<Func<T, bool>> Filter { get; set; }

        public IQueryOption<T> FilterBy(Expression<Func<T, bool>> filter)
        {
            Filter = filter;
            return this;
        }

        public IQueryOption<T> AddEagerLoad(Expression<Func<T, object>> eagerLoad)
        {
            if (EagerLoads == null)
                EagerLoads = new List<Expression<Func<T, object>>>();

            EagerLoads.Add(eagerLoad);
            return this;
        }

        public IQueryable<T> Process()
        {
            foreach (var eagerload in EagerLoads ?? new List<Expression<Func<T, object>>>())
            _queryable.Include(eagerload);

            return _queryable.Where(Filter ?? (x => true));
        }
    }