C# DataTable 和List之间相互转换的方法

介绍：List/IEnumerable转换到DataTable/DataView，以及DataTable转换到List

正文：

一、List<T>/IEnumerable转换到DataTable/DataView

方法一：

 1 /// <summary>

 2 /// Convert a List{T} to a DataTable.

 3 /// </summary>

 4 private DataTable ToDataTable<T>(List<T> items)

 5 {

 6     var tb = new DataTable(typeof (T).Name);

 7  

 8     PropertyInfo[] props = typeof (T).GetProperties(BindingFlags.Public | BindingFlags.Instance);

 9  

10     foreach (PropertyInfo prop in props)

11     {

12         Type t = GetCoreType(prop.PropertyType);

13         tb.Columns.Add(prop.Name, t);

14     }

15  

16     foreach (T item in items)

17     {

18         var values = new object[props.Length];

19  

20         for (int i = 0; i < props.Length; i++)

21         {

22             values[i] = props[i].GetValue(item, null);

23         }

24  

25         tb.Rows.Add(values);

26     }

27  

28     return tb;

29 }

30  

31 /// <summary>

32 /// Determine of specified type is nullable

33 /// </summary>

34 public static bool IsNullable(Type t)

35 {

36     return !t.IsValueType || (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Nullable<>));

37 }

38  

39 /// <summary>

40 /// Return underlying type if type is Nullable otherwise return the type

41 /// </summary>

42 public static Type GetCoreType(Type t)

43 {

44     if (t != null && IsNullable(t))

45     {

46         if (!t.IsValueType)

47         {

48             return t;

49         }

50         else

51         {

52             return Nullable.GetUnderlyingType(t);

53         }

54     }

55     else

56     {

57         return t;

58     }

59 }

View Code

方法二：

 1 public static DataTable ToDataTable<T>(IEnumerable<T> collection)

 2  {

 3      var props = typeof(T).GetProperties();

 4      var dt = new DataTable();

 5      dt.Columns.AddRange(props.Select(p => new DataColumn(p.Name, p.PropertyType)).ToArray());

 6      if (collection.Count() > 0)

 7      {

 8          for (int i = 0; i < collection.Count(); i++)

 9          {

10              ArrayList tempList = new ArrayList();

11              foreach (PropertyInfo pi in props)

12              {

13                  object obj = pi.GetValue(collection.ElementAt(i), null);

14                  tempList.Add(obj);

15              }

16              object[] array = tempList.ToArray();

17              dt.LoadDataRow(array, true);

18          }

19      }

20      return dt;

21  }

View Code

二、DataTable转换到List

方法一:

public static IList<T> ConvertTo<T>(DataTable table)  

{  

   if (table == null)  

   {  

       return null;  

   }  

 

   List<DataRow> rows = new List<DataRow>();  

 

   foreach (DataRow row in table.Rows)  

   {  

       rows.Add(row);  

   }  

 

   return ConvertTo<T>(rows);  

}  

 

public static IList<T> ConvertTo<T>(IList<DataRow> rows)  

{  

   IList<T> list = null;  

 

   if (rows != null)  

   {  

       list = new List<T>();  

 

       foreach (DataRow row in rows)  

       {  

           T item = CreateItem<T>(row);  

           list.Add(item);  

       }  

   }  

 

   return list;

}    

 

public static T CreateItem<T>(DataRow row)    

{

    T obj = default(T);    

    if (row != null)    

    {    

       obj = Activator.CreateInstance<T>();    

 

       foreach (DataColumn column in row.Table.Columns)    

       {    

           PropertyInfo prop = obj.GetType().GetProperty(column.ColumnName);    

           try   

           {    

               object value = row[column.ColumnName];    

               prop.SetValue(obj, value, null);    

           }    

           catch   

           {  //You can log something here     

               //throw;    

           }    

       }    

    }    

 

return obj;    

}

View Code

方法二:

把查询结果以DataTable返回很方便，但是在检索数据时又很麻烦，没有模型类型检索方便。   

所以很多人都是按照以下方式做的：  

1 // 获得查询结果  

2 DataTable dt = DbHelper.ExecuteDataTable(...);  

3 // 把DataTable转换为IList<UserInfo>  

4 IList<UserInfo> users = ConvertToUserInfo(dt);

View Code

问题：如果此系统有几十上百个模型，那不是每个模型中都要写个把DataTable转换为此模型的方法吗？  

解决：能不能写个通用类，可以把DataTable转换为任何模型，呵呵，这就需要利用反射和泛型了  

 1 using System;      

 2 using System.Collections.Generic;  

 3 using System.Text;    

 4 using System.Data;    

 5 using System.Reflection;  

 6 namespace NCL.Data    

 7 {    

 8     /// <summary>    

 9     /// 实体转换辅助类    

10     /// </summary>    

11     public class ModelConvertHelper<T> where   T : new()    

12      {    

13         public static IList<T> ConvertToModel(DataTable dt)    

14          {    

15             // 定义集合    

16              IList<T> ts = new List<T>(); 

17      

18             // 获得此模型的类型   

19              Type type = typeof(T);      

20             string tempName = "";      

21       

22             foreach (DataRow dr in dt.Rows)      

23              {    

24                  T t = new T();     

25                 // 获得此模型的公共属性      

26                  PropertyInfo[] propertys = t.GetType().GetProperties(); 

27                 foreach (PropertyInfo pi in propertys)      

28                  {      

29                      tempName = pi.Name;  // 检查DataTable是否包含此列    

30    

31                     if (dt.Columns.Contains(tempName))      

32                      {      

33                         // 判断此属性是否有Setter      

34                         if (!pi.CanWrite) continue;         

35    

36                         object value = dr[tempName];      

37                         if (value != DBNull.Value)      

38                              pi.SetValue(t, value, null);  

39                      }     

40                  }      

41                  ts.Add(t);      

42              }     

43             return ts;     

44          }     

45      }    

46 }

View Code

使用方式：  

1 // 获得查询结果  

2 DataTable dt = DbHelper.ExecuteDataTable(...);  

3 // 把DataTable转换为IList<UserInfo>  

4 IList<UserInfo> users = ModelConvertHelper<UserInfo>.ConvertToModel(dt);

View Code

refer to: http://www.okbase.net/doc/details/3282