DataTable與List相互轉換

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 Common
{
    public class ModelHelper
    {
        public static List<T> TableToEntity<T>(DataTable dt) where T : new()
        {
            List<T> lists = new List<T>();
            if (dt.Rows.Count > 0)
            {
                foreach (DataRow row in dt.Rows)
                {
                    lists.Add(SetVal(new T(), row));
                }
            }
            return lists;
        }

        public static T SetVal<T>(T entity, DataRow row) where T : new()
        {
            Type type = typeof(T);
            PropertyInfo[] pi = type.GetProperties();
            foreach (PropertyInfo item in pi)
            {
                if (row[item.Name] != null && row[item.Name] != DBNull.Value)
                {
                    if (item.PropertyType.IsGenericType && item.PropertyType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
                    {
                        Type conversionType = item.PropertyType;
                        NullableConverter nullableConverter = new NullableConverter(conversionType);
                        conversionType = nullableConverter.UnderlyingType;
                        item.SetValue(entity, Convert.ChangeType(row[item.Name], conversionType), null);
                    }
                    else
                    {
                        item.SetValue(entity, Convert.ChangeType(row[item.Name], item.PropertyType), null);
                    }
                }
            }
            return entity;
        }

        public static DataTable EntityToDataTable<T>(List<T> list) where T : new()
        {
            if (list == null || list.Count == 0)
            {
                return null;
            }

            DataTable dataTable = new DataTable(typeof(T).Name);
            foreach (PropertyInfo propertyInfo in typeof(T).GetProperties())
            {
                if (propertyInfo.PropertyType.IsGenericType && propertyInfo.PropertyType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
                {
                    Type conversionType = propertyInfo.PropertyType;
                    NullableConverter nullableConverter = new NullableConverter(conversionType);
                    conversionType = nullableConverter.UnderlyingType;
                    dataTable.Columns.Add(new DataColumn(propertyInfo.Name, conversionType));
                }
                else
                {
                    dataTable.Columns.Add(new DataColumn(propertyInfo.Name, propertyInfo.PropertyType));
                }
            }

            foreach (T model in list)
            {
                DataRow dataRow = dataTable.NewRow();
                foreach (PropertyInfo propertyInfo in typeof(T).GetProperties())
                {
                    object value = propertyInfo.GetValue(model, null);
                    if (value != null)
                    {
                        dataRow[propertyInfo.Name] = propertyInfo.GetValue(model, null);
                    }
                    else
                    {
                        dataRow[propertyInfo.Name] = DBNull.Value;
                    }
                }
                dataTable.Rows.Add(dataRow);
            }
            return dataTable;
        }
    }
}