C# DataTable，DataSet，IList，IEnumerable 互转扩展属性
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Reflection;
using System.Collections;
namespace XHSoft.LicenseManagerUI
{
/// <summary>
/// 扩展属性
/// </summary>
public static class Extensions
{
#region 数据集转换泛型集合扩展
/// <summary>
/// DataSet转换为泛型集合
/// </summary>
/// <typeparam name="T">泛型类型</typeparam>
/// <param name="ds">DataSet数据集</param>
/// <param name="tableIndex">待转换数据表索引,默认第0张表</param>
/// <returns>返回泛型集合</returns>
public static IList<T> ToList<T>(this DataSet ds, int tableIndex = 0)
{
if (ds == null || ds.Tables.Count < 0) return null;
if (tableIndex > ds.Tables.Count - 1)
return null;
if (tableIndex < 0)
tableIndex = 0;
DataTable dt = ds.Tables[tableIndex];
// 返回值初始化
IList<T> result = new List<T>();
for (int j = 0; j < dt.Rows.Count; j++)
{
T _t = (T)Activator.CreateInstance(typeof(T));
PropertyInfo[] propertys = _t.GetType().GetProperties();
foreach (PropertyInfo pi in propertys)
{
for (int i = 0; i < dt.Columns.Count; i++)
{
// 属性与字段名称一致的进行赋值
if (pi.Name.Equals(dt.Columns[i].ColumnName))
{
// 数据库NULL值单独处理
if (dt.Rows[j][i] != DBNull.Value)
pi.SetValue(_t, dt.Rows[j][i], null);
else
pi.SetValue(_t, null, null);
break;
}
}
}
result.Add(_t);
}
return result;
}
/// <summary>
/// DataTable转换为泛型集合
/// </summary>
/// <typeparam name="T">泛型类型</typeparam>
/// <param name="dt">DataTable数据表</param>
/// <returns>返回泛型集合</returns>
public static IList<T> ToList<T>(this DataTable dt) where T:class,new()
{
if (dt == null || dt.Rows.Count <= 0) return null;
List<T> list =new List<T>();
#region 方法一：
//T model;
//Type infos = typeof(T);
////object tempValue;
//foreach (DataRow dr in dt.Rows)
//{
// model = new T();
// 1.
// infos.GetProperties().ToList().ForEach(p =>p.SetValue(model, dr[p.Name], null));
// 2.
// //infos.GetProperties().ToList().ForEach(p =>
// //{
// // tempValue = dr[p.Name];
// // if (!string.IsNullOrEmpty(tempValue.ToString()))
// // p.SetValue(model, tempValue, null);
// //});
// list.Add(model);
//}
#endregion
#region 方法二： 比方法一快
PropertyInfo[] propertys = typeof(T).GetProperties();
for (int j = 0; j < dt.Rows.Count; j++)
{
T _t = (T)Activator.CreateInstance(typeof(T));
foreach (PropertyInfo pi in propertys)
{
// 属性与字段名称一致的进行赋值
if (pi.Name.Equals(dt.Columns[pi.Name].ColumnName))
{
if (dt.Rows[j][pi.Name] != DBNull.Value)
pi.SetValue(_t, dt.Rows[j][pi.Name], null);
else
pi.SetValue(_t, null, null);
}
}
list.Add(_t);
}
#endregion
return list;
}
/// <summary>
/// DataSet转换为泛型集合
/// </summary>
/// <typeparam name="T">泛型类型</typeparam>
/// <param name="ds">DataSet数据集</param>
/// <param name="tableName">待转换数据表名称,名称为空时默认第0张表</param>
/// <returns>返回泛型集合</returns>
public static IList<T> ToList<T>(this DataSet ds, string tableName)
{
int _TableIndex = 0;
if (ds == null || ds.Tables.Count < 0)
return null;
if (string.IsNullOrEmpty(tableName))
return ToList<T>(ds, 0);
for (int i = 0; i < ds.Tables.Count; i++)
{
// 获取Table名称在Tables集合中的索引值
if (ds.Tables[i].TableName.Equals(tableName))
{
_TableIndex = i;
break;
}
}
return ToList<T>(ds, _TableIndex);
}
#endregion
#region 泛型集合转换为数据集扩展
/// <summary>
/// 将泛型集合转换成DataSet数据集
/// </summary>
/// <typeparam name="T">T类型</typeparam>
/// <param name="list">泛型集合</param>
/// <returns>DataSet数据集</returns>
public static DataSet ToDataSet<T>(this IList<T> list)
{
Type elementType = typeof(T);
var ds = new DataSet();
var t = new DataTable();
ds.Tables.Add(t);
elementType.GetProperties().ToList().ForEach(propInfo => t.Columns.Add(propInfo.Name, Nullable.GetUnderlyingType(propInfo.PropertyType) ?? propInfo.PropertyType));
foreach (T item in list)
{
var row = t.NewRow();
elementType.GetProperties().ToList().ForEach(propInfo => row[propInfo.Name] = propInfo.GetValue(item, null) ?? DBNull.Value);
t.Rows.Add(row);
}
return ds;
}
/// <summary>
/// 泛型集合转换成DataTable表
/// </summary>
/// <typeparam name="T">T类型</typeparam>
/// <param name="list">泛型集合</param>
/// <returns>DataTable表</returns>
public static DataTable ToDataTable<T>(this IList<T> list)
{
return ToDataTable(list, null);
}
/// <summary>
/// 泛型集合转换成DataTable表
/// </summary>
/// <typeparam name="T">T类型</typeparam>
/// <param name="list">泛型集合</param>
/// <param name="_tableName">Table名称</param>
/// <returns>DataTable表</returns>
public static DataTable ToDataTable<T>(this IList<T> list, string _tableName)
{
Type elementType = typeof(T);
var dt = new DataTable();
if (_tableName == "null")
dt.TableName = _tableName;
elementType.GetProperties().ToList().ForEach(propInfo => dt.Columns.Add(propInfo.Name, Nullable.GetUnderlyingType(propInfo.PropertyType) ?? propInfo.PropertyType));
foreach (T item in list)
{
var row = dt.NewRow();
elementType.GetProperties().ToList().ForEach(propInfo => row[propInfo.Name] = propInfo.GetValue(item, null) ?? DBNull.Value);
dt.Rows.Add(row);
}
return dt;
}
#endregion
#region 以下为IEnumerable扩展实现
/// <summary>
/// 给非强类型的IEnumerable返回头一个元素。
/// </summary>
public static object First(this IEnumerable col)
{
foreach (var item in col)
return item;
throw new IndexOutOfRangeException();
}
/// <summary>
/// 给非强类型的IEnumerable返回头一个强类型的元素
/// </summary>
public static object First<T>(this IEnumerable col)
{
return (T)col.First();
}
/// <summary>
/// 基本上和List<T>的ForEach方法一致。
/// </summary>
public static void Each<T>(this IEnumerable<T> col, Action<T> handler)
{
foreach (var item in col)
handler(item);
}
/// <summary>
/// 带索引的遍历方法。
/// </summary>
public static void Each<T>(this IEnumerable<T> col, Action<T, int> handler)
{
int index = 0;
foreach (var item in col)
handler(item, index++);
}
/// <summary>
/// 可以半途中断执行的遍历方法。
/// </summary>
public static void Each<T>(this IEnumerable<T> col, Func<T, bool> handler)
{
foreach (var item in col)
if (!handler(item)) break;
}
/// <summary>
/// 可以半途中段的带索引的遍历方法。
/// </summary>
public static void Each<T>(this IEnumerable<T> col, Func<T, int, bool> handler)
{
int index = 0;
foreach (var item in col)
if (!handler(item, index++)) break;
}
#endregion
#region 以下为IEnumerable<T>的非泛型实现
public static void Each<T>(this IEnumerable col, Action<object> handler)
{
foreach (var item in col)
handler(item);
}
public static void Each<T>(this IEnumerable col, Action<object, int> handler)
{
int index = 0;
foreach (var item in col)
handler(item, index++);
}
public static void Each<T>(this IEnumerable col, Func<object, bool> handler)
{
foreach (var item in col)
if (!handler(item)) break;
}
public static void Each<T>(this IEnumerable col, Func<object, int, bool> handler)
{
int index = 0;
foreach (var item in col)
if (!handler(item, index++)) break;
}
#endregion
}
}
