C# datatable to list

C# DataTable 和List之间相互转换的方法

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发布者：好饱 

发布日期：2013-1-27 22:17:49   更新日期：2013-1-27 22:18:55

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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：

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/// <summary> /// Convert a List{T} to a DataTable. /// </summary> private DataTable ToDataTable<T>(List<T> items) {     var tb = new DataTable(typeof (T).Name);       PropertyInfo[] props = typeof (T).GetProperties(BindingFlags.Public | BindingFlags.Instance);       foreach (PropertyInfo prop in props)     {         Type t = GetCoreType(prop.PropertyType);         tb.Columns.Add(prop.Name, t);     }       foreach (T item in items)     {         var values = new object[props.Length];           for (int i = 0; i < props.Length; i++)         {             values[i] = props[i].GetValue(item, null);         }           tb.Rows.Add(values);     }       return tb; }   /// <summary> /// Determine of specified type is nullable /// </summary> public static bool IsNullable(Type t) {     return !t.IsValueType || (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Nullable<>)); }   /// <summary> /// Return underlying type if type is Nullable otherwise return the type /// </summary> public static Type GetCoreType(Type t) {     if (t != null && IsNullable(t))     {         if (!t.IsValueType)         {             return t;         }         else         {             return Nullable.GetUnderlyingType(t);         }     }     else     {         return t;     } }

方法二：

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public static DataTable ToDataTable<T>(IEnumerable<T> collection)  {      var props = typeof(T).GetProperties();      var dt = new DataTable();      dt.Columns.AddRange(props.Select(p => new DataColumn(p.Name, p.PropertyType)).ToArray());      if (collection.Count() > 0)      {          for (int i = 0; i < collection.Count(); i++)          {              ArrayList tempList = new ArrayList();              foreach (PropertyInfo pi in props)              {                  object obj = pi.GetValue(collection.ElementAt(i), null);                  tempList.Add(obj);              }              object[] array = tempList.ToArray();              dt.LoadDataRow(array, true);          }      }      return dt;  }

二、DataTable转换到List

方法一:

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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;    }

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：

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// 获得查询结果  DataTable dt = DbHelper.ExecuteDataTable(...);  // 把DataTable转换为IList<UserInfo>  IList<UserInfo> users = ConvertToUserInfo(dt);

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

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using System;      using System.Collections.Generic;  using System.Text;    using System.Data;    using System.Reflection;  namespace NCL.Data    {        /// <summary>        /// 实体转换辅助类        /// </summary>        public class ModelConvertHelper<T> where   T : new()         {            public static IList<T> ConvertToModel(DataTable dt)             {                // 定义集合                 IList<T> ts = new List<T>();                   // 获得此模型的类型                Type type = typeof(T);                  string tempName = "";                         foreach (DataRow dr in dt.Rows)                   {                     T t = new T();                     // 获得此模型的公共属性                       PropertyInfo[] propertys = t.GetType().GetProperties();                 foreach (PropertyInfo pi in propertys)                       {                           tempName = pi.Name;  // 检查DataTable是否包含此列                            if (dt.Columns.Contains(tempName))                           {                              // 判断此属性是否有Setter                              if (!pi.CanWrite) continue;                                     object value = dr[tempName];                              if (value != DBNull.Value)                                   pi.SetValue(t, value, null);                       }                      }                       ts.Add(t);                   }                 return ts;              }          }    }

使用方式：

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// 获得查询结果  DataTable dt = DbHelper.ExecuteDataTable(...);  // 把DataTable转换为IList<UserInfo>  IList<UserInfo> users = ModelConvertHelper<UserInfo>.ConvertToModel(dt);