將DataTable數據轉化為Model對象列表

最近做項目實現了自動將DataTable對象中的數據轉化為制定Model類型對象列表的功能，這里做記錄：

因為開發過程中往往是要分層的，所以經常要將從數據庫中查詢出來的數據轉變成為對象形式，所以在這里定義了一個ModelConvertor類，用於將從數據庫查詢出來的表形式數據轉化為模型層對象，為了增加通用性，這里使用了泛型，當需要將數據轉化為制定Model列表時，只需要加上泛型參數即可。

首先是定義轉化類 ：

 

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace ClassView
{
    /// <summary>
    ///     進行從 DataTable 或者實現 IDataReader 接口的對象讀取記錄
    ///     並將結果集轉換為給定類型列表的方法。
    /// </summary>
    public class ModelConvetor
    {
        /// <summary>
        ///     從 reader 對象中逐行讀取記錄並將記錄轉化為 T 類型的集合
        /// </summary>
        /// <typeparam name="T">目標類型參數</typeparam>
        /// <param name="reader">實現 IDataReader 接口的對象。</param>
        /// <returns>指定類型的對象集合。</returns>
        public static List<T> ConvertToObject<T>(IDataReader reader)
            where T : class
        {
            List<T> list = new List<T>();
            T obj = default(T);
            Type t = typeof(T);
            Assembly ass = t.Assembly;

            Dictionary<string, PropertyInfo> propertys = ModelConvetor.GetFields<T>(reader);
            PropertyInfo p = null;
            if (reader != null)
            {
                while (reader.Read())
                {
                    obj = ass.CreateInstance(t.FullName) as T;
                    foreach (string key in propertys.Keys)
                    {
                        p = propertys[key];
                        p.SetValue(obj, ModelConvetor.ChangeType(reader[key], p.PropertyType));
                    }
                    list.Add(obj);
                }
            }

            return list;
        }

        /// <summary>
        ///     從 DataTale 對象中逐行讀取記錄並將記錄轉化為 T 類型的集合
        /// </summary>
        /// <typeparam name="T">目標類型參數</typeparam>
        /// <param name="reader">DataTale 對象。</param>
        /// <returns>指定類型的對象集合。</returns>
        public static List<T> ConvertToObject<T>(DataTable table)
            where T : class
        {
            return table == null
                ? new List<T>()
                : ModelConvetor.ConvertToObject<T>(table.CreateDataReader() as IDataReader);
        }

        /// <summary>
        ///     將數據轉化為 type 類型
        /// </summary>
        /// <param name="value">要轉化的值</param>
        /// <param name="type">目標類型</param>
        /// <returns>轉化為目標類型的 Object 對象</returns>
        private static object ChangeType(object value, Type type)
        {
            if (type.FullName == typeof(string).FullName)
            {
                return Convert.ChangeType(Convert.IsDBNull(value) ? null : value, type);
            }
            if (type.IsGenericType && type.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
            {
                NullableConverter convertor = new NullableConverter(type);
                return Convert.IsDBNull(value) ? null : convertor.ConvertFrom(value);
            }
            return value;
        }

        /// <summary>
        ///     獲取reader存在並且在 T 類中包含同名可寫屬性的集合
        /// </summary>
        /// <param name="reader">
        ///     可寫域的集合
        /// </param>
        /// <returns>
        ///     以屬性名為鍵，PropertyInfo 為值得字典對象
        /// </returns>
        private static Dictionary<string, PropertyInfo> GetFields<T>(IDataReader reader)
        {
            Dictionary<string, PropertyInfo> result = new Dictionary<string, PropertyInfo>();
            int columnCount = reader.FieldCount;
            Type t = typeof(T);

            PropertyInfo[] properties = t.GetProperties();
            if (properties != null)
            {
                List<string> readerFields = new List<string>();
                for (int i = 0; i < columnCount; i++)
                {
                    readerFields.Add(reader.GetName(i));
                }
                IEnumerable<PropertyInfo> resList =
                    (from PropertyInfo prop in properties
                     where prop.CanWrite && readerFields.Contains(prop.Name)
                     select prop);

                foreach (PropertyInfo p in resList)
                {
                    result.Add(p.Name, p);
                }
            }
            return result;
        }
    }
}

接下來是測試類型：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ClassView
{
    public class TestObj
    {
        public int? UserID { get; set; }
        public string UserName { get; set; }
        public decimal? Height { get; set; }
        public DateTime? Birthday { get; set; }
    }
}

最后是測試代碼：

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ClassView
{
    class Program
    {
        static void Main(string[] args)
        {
            DataTable table = new DataTable();
            table.Columns.AddRange(new DataColumn[]
                {
                    new DataColumn("UserID"),
                    new DataColumn("UserName"),
                    new DataColumn("Height"),
                    new DataColumn("Birthday")
                });
            for (int i = 0; i < 10; i++)
            {
                DataRow row = table.NewRow();
                row["UserID"] = i % 2 == 0 ? DBNull.Value : i as object;
                row["UserName"] = "User" + i;
                row["Height"] = i % 5 == 0 ? DBNull.Value : (i + 5) as object;
                row["Birthday"] = i % 3 == 0 ? DBNull.Value : (DateTime.Now) as object;
                table.Rows.Add(row);
            }
            List<TestObj> res = ModelConvetor.ConvertToObject<TestObj>(table);
            foreach (TestObj o in res)
            {
                Console.WriteLine(string.Format("UserID:{0}",o.UserID));
                Console.WriteLine(string.Format("UserName:{0}", o.UserName));
                Console.WriteLine(string.Format("Height:{0}", o.Height));
                Console.WriteLine(string.Format("Birthday:{0}", o.Birthday));
                Console.WriteLine("-------------------------------------------------------------------------");
            }
            Console.ReadLine();
        }
    }
}

執行結果如下：

 

 

下次是配置數據庫代碼，to be continue ...