解决DataSet不支持System.nullable

转自:http://www.cnblogs.com/zoofooo/archive/2012/08/02/2619669.html

 1 using System;
 2 using System.Data;
 3 using System.Collections;
 4 using System.Collections.Generic;
 5 using System.Configuration;
 6 using System.Reflection;
 7 using System.Linq;
 8 using System.Xml.Linq;
 9 
10 namespace UserFunction
11 {
12     /// <summary>
13     /// Summary description for LinqToDataTable
14     /// </summary>
15     static public  class LinqToDataTable
16     {
17         static public  DataTable ToDataTable<T>(this IEnumerable<T> varlist, CreateRowDelegate<T> fn)
18         {
19 
20             DataTable dtReturn = new DataTable();
21 
22             // column names
23 
24             PropertyInfo[] oProps = null;
25 
26             // Could add a check to verify that there is an element 0
27 
28             foreach (T rec in varlist)
29             {
30 
31                 // Use reflection to get property names, to create table, Only first time, others will follow
32 
33                 if (oProps == null)
34                 {
35 
36                     oProps = ((Type)rec.GetType()).GetProperties();
37 
38                     foreach (PropertyInfo pi in oProps)
39                     {
40 　　　　　　　　　　　　　　// 当字段类型是Nullable<>时
41                         Type colType = pi.PropertyType; if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition() == typeof(Nullable<>)))
42                         {
43 
44                             colType = colType.GetGenericArguments()[0];
45 
46                         }
47 
48                         dtReturn.Columns.Add(new DataColumn(pi.Name, colType));
49 
50                     }
51 
52                 }
53 
54                 DataRow dr = dtReturn.NewRow(); foreach (PropertyInfo pi in oProps)
55                 {
56 
57                     dr[pi.Name] = pi.GetValue(rec, null) == null ? DBNull.Value : pi.GetValue(rec, null);
58 
59                 }
60 
61                 dtReturn.Rows.Add(dr);
62 
63             }
64 
65             return (dtReturn);
66 
67         }
68 
69         public delegate object[] CreateRowDelegate<T>(T t);
70     }
71 }
72 
73 /*
74  * 示例:
75  * var query = from ....;
76  * DataTable dt = query.ToDataTable(rec => new object[] { query });
77  *
78 */