Freesql ORM 多条件枚举Sum

反射枚举 desc 建拉姆达查询 sum

        /// <summary>
        /// 创建lambda表达式：p=>p.propertyName 
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="propertyName"></param> 
        /// <returns></returns>
        public static Expression<Func<T, int>> CreatePropertyName<T>(string propertyName)
        {
            ParameterExpression parameter = Expression.Parameter(typeof(T), "p");//创建参数p
            MemberExpression member = Expression.PropertyOrField(parameter, propertyName);
            return Expression.Lambda<Func<T, int>>( member , parameter);
        } 

定义

    public enum sexID
    {
        [Description("Id")]
        Id_1 ,
        [Description("Id2")]
        Id_2,
        [Description("Id3")]
        Id_3

    }

    [Index("Idu001", "Idu", true)]
    public class Item
    {
        [Column(IsIdentity = true, IsPrimary = true)]
        [DisplayName("序号")]
        public int Id { get; set; }
        public int Id2 { get; set; }
        public int Id3 { get; set; }

        [DisplayName("名称")]
        public string Text { get; set; }

        [DisplayName("描述")]
        public string Description { get; set; }

        [Column(IsPrimary = true)]
        [DisplayName("序号U")]
        public Guid Idu { get; set; }
    }

代码

            Expression<Func<Item, int>> sum = null;
            sum = LambadaExpression.CreatePropertyName<Item>("Id");
            var sums=fsql.Select<Item>().Sum(sum);//SELECT sum(a."Id") as1 FROM "Item" a

            sum = LambadaExpression.CreatePropertyName<Item>(sexID.Id_2.ToDescriptionOrString());
            var sums2=fsql.Select<Item>().Sum(sum);//SELECT sum(a."Id2") as1 FROM "Item" a

            sum = LambadaExpression.CreatePropertyName<Item>(sexID.Id_3.ToDescriptionOrString());
            var sums3=fsql.Select<Item>().Sum(sum);//SELECT sum(a."Id3") as1 FROM "Item" a