C#:DataTable映射成Model

这是数据库开发中经常遇到的问题,当然,这可以用现成的ORM框架来解决,但有些时候,如果DataSet/DataTable是第三方接口返回的,ORM就不方便了,还得自己处理。

反射自然必不可少的,另外考虑到DataTable中的ColumnName通常与Model的PropertyName并不严格对应,可以用Attribute来记录这种映射关系。

步骤1:先创建一个DataFieldAttribute类 

using System;
 2 
 3 namespace Jimmy.ORM
 4 {
 5     [AttributeUsage(AttributeTargets.Property)]
 6     public sealed class DataFieldAttribute:Attribute
 7     {
 8         /// <summary>
 9         /// 表对应的字段名
10         /// </summary>
11         public string ColumnName { set; get; }
12 
13         public DataFieldAttribute(string columnName)
14         {
15             ColumnName = columnName;
16         }
17     }
18 }

 

步骤2:在Model/Entity的Class成员上,应用DataField特性,参见下面的代码:

 

using System;

namespace Jimmy.ORM.Entity
{
    [Serializable]
    public class ProductEntity : DataEntityBase
    {

        [DataField("PRODUCT_NO")]
        public string ProductNo { set; get; }

        [DataField("PRODUCT_ID")]
        public int ProductId { set; get; }

        [DataField("PRODUCT_NAME")]
        public string ProductName { set; get; }

        public override string ToString()
        {
            return string.Format("ProductNo:{1}{0}ProductId:{2}{0}ProductName:{3}", Environment.NewLine, ProductNo,
                                 ProductId, ProductName);
        }
    }
}

 

步骤3:该反射出场了,为了方便起见,封装了一个DataConvert类

 

using System;
using System.Collections.Generic;
using System.Data;
using System.Reflection;

namespace Jimmy.ORM
{
    /// <summary>
    /// 将DataRow/DataTable转换成Entity/Entity列表
    /// </summary>
    public static class DataConvert<T> where T : DataEntityBase, new()
    {
        /// <summary>
        /// 将DataRow行转换成Entity
        /// </summary>
        /// <param name="dr"></param>
        /// <returns></returns>
        public static T ToEntity(DataRow dr)
        {
            T entity = new T();
            Type info = typeof(T);
            var members = info.GetMembers();
            foreach (var mi in members)
            {
                if (mi.MemberType == MemberTypes.Property)
                {
                    //读取属性上的DataField特性
                    object[] attributes = mi.GetCustomAttributes(typeof(DataFieldAttribute), true);
                    foreach (var attr in attributes)
                    {
                        var dataFieldAttr = attr as DataFieldAttribute;
                        if (dataFieldAttr != null)
                        {
                            var propInfo = info.GetProperty(mi.Name);
                            if (dr.Table.Columns.Contains(dataFieldAttr.ColumnName))
                            {
                                //根据ColumnName,将dr中的相对字段赋值给Entity属性
                                propInfo.SetValue(entity,
                                                  Convert.ChangeType(dr[dataFieldAttr.ColumnName], propInfo.PropertyType),
                                                  null);
                            }

                        }
                    }
                }
            }
            return entity;
        }

        /// <summary>
        /// 将DataTable转换成Entity列表
        /// </summary>
        /// <param name="dt"></param>
        /// <returns></returns>
        public static List<T> ToList(DataTable dt)
        {
            List<T> list = new List<T>(dt.Rows.Count);
            foreach (DataRow dr in dt.Rows)
            {
                list.Add(ToEntity(dr));
            }
            return list;
        }
    }
}

 

步骤4:测试

using System;
using System.Data;
using Jimmy.ORM.Entity;

namespace Jimmy.ORM.Test
{
    class Program
    {
        static void Main()
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("PRODUCT_NO");
            dt.Columns.Add("PRODUCT_ID");
            dt.Columns.Add("PRODUCT_NAME");

            dt.Rows.Add("00001", 1, "手机");
            dt.Rows.Add("00002", 2, "服装");

            var products = DataConvert<ProductEntity>.ToList(dt);

            foreach (var entity in products)
            {
                Console.WriteLine(entity);
            }

            Console.Read();
        }
    }
}

 

posted @ 2016-05-18 13:21  Franson  阅读(4725)  评论(0编辑  收藏  举报