List和DataTable相互转换

来源：互联网发布：java 实现在线订票系统编辑：程序博客网时间：2024/06/05 20:07
转载：http://www.okbase.net/doc/details/3282
一、List<T>/IEnumerable转换到DataTable/DataView方法一：/// <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：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: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：  // 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  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：  // 获得查询结果  DataTable dt = DbHelper.ExecuteDataTable(...);  // 把DataTable转换为IList<UserInfo>  IList<UserInfo> users = ModelConvertHelper<UserInfo>.ConvertToModel(dt);
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