CODE-將LINQ查詢結果轉成ADO.NET DataTable

using System;

using System.Collections.Generic;

using System.Linq;

using System.Data;

using System.Reflection;

namespace ConsoleApplication1

{

    class Program

    {

        //REF: http://3.ly/y8rA

        //註: .NET 3.5有個IEnumerable.CopyToDataTable<T>()，但T只接受DataRow(感覺有點莊孝維)

        static DataTable LinqQueryToDataTable<T>(IEnumerable<T> query)

        {

            DataTable tbl = new DataTable();

            PropertyInfo[] props = null;

            foreach (T item in query)

            {

                if (props == null) //尚未初始化

                {

                    Type t = item.GetType();

                    props = t.GetProperties();

                    foreach (PropertyInfo pi in props)

                    {

                        Type colType = pi.PropertyType;

                        //針對Nullable<>特別處理

                        if (colType.IsGenericType

                            && colType.GetGenericTypeDefinition() == typeof(Nullable<>))

                            colType = colType.GetGenericArguments()[0];

                        //建立欄位

                        tbl.Columns.Add(pi.Name, colType);

                    }

                }

                DataRow row = tbl.NewRow();

                foreach (PropertyInfo pi in props)

                    row[pi.Name] = pi.GetValue(item, null) ?? DBNull.Value;

                tbl.Rows.Add(row);

            }

            return tbl;

        }

        class Person

        {

            public string Name { get; set; }

            public int Score { get; set; }

            public DateTime RegDate { get; set; }

        }

        static void Main(string[] args)

        {

            List<Person> people = new List<Person>() {

                new Person { Name="Jeffrey", Score=32767, RegDate = DateTime.Today },

                new Person { Name="Darkthread", Score=65535, RegDate = DateTime.Now }

            };

            var q = from p in people

                    where p.Score > 255

                    select p;

            DataTable t = LinqQueryToDataTable(q);

            Console.WriteLine("Row Count={0}", t.Rows.Count);

            DataRow r = t.Rows[0];

            Console.WriteLine("1st Person Name={0} Score={1} RegDate={2}",

                r["Name"], r["Score"], r["RegDate"]);

            Console.Read();

        }

    }

}