List<T> 和DataTable的相互转换

/// <summary>
/// 将集合类转换成DataTable
/// </summary>
/// <param name="list">集合</param>
/// <returns></returns>
private static DataTable ToDataTableTow(IList list)
{
DataTable result = new DataTable();
if (list.Count > 0)
{
PropertyInfo[] propertys = list[0].GetType().GetProperties();

foreach (PropertyInfo pi in propertys)
{
result.Columns.Add(pi.Name, pi.PropertyType);
}
foreach (object t in list)
{
ArrayList tempList = new ArrayList();
foreach (PropertyInfo pi in propertys)
{
object obj = pi.GetValue(t, null);
tempList.Add(obj);
}
object[] array = tempList.ToArray();
result.LoadDataRow(array, true);
}
}
return result;
}

/// <summary>
/// DataTable 转换为List 集合
/// </summary>
/// <typeparam name="TResult">类型</typeparam>
/// <param name="dt">DataTable</param>
/// <returns></returns>
public static List<T> ToList<T>(this DataTable dt) where T : class, new()
{
//创建一个属性的列表
List<PropertyInfo> prlist = new List<PropertyInfo>();
//获取TResult的类型实例  反射的入口

Type t = typeof(T);

//获得TResult 的所有的Public 属性 并找出TResult属性和DataTable的列名称相同的属性(PropertyInfo) 并加入到属性列表
Array.ForEach<PropertyInfo>(t.GetProperties(), p => { if (dt.Columns.IndexOf(p.Name) != -1) prlist.Add(p); });

//创建返回的集合

List<T> oblist = new List<T>();

foreach (DataRow row in dt.Rows)
{
//创建TResult的实例
T ob = new T();
//找到对应的数据  并赋值
prlist.ForEach(p => { if (row[p.Name] != DBNull.Value) p.SetValue(ob, row[p.Name], null); });
//放入到返回的集合中.
oblist.Add(ob);
}
return oblist;
}

/// <summary>
/// 转化一个DataTable
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="list"></param>
/// <returns></returns>
public static DataTable ToDataTable<T>(this IEnumerable<T> list)
{
//创建属性的集合
List<PropertyInfo> pList = new List<PropertyInfo>();
//获得反射的入口
Type type = typeof(T);
DataTable dt = new DataTable();
//把所有的public属性加入到集合 并添加DataTable的列
Array.ForEach<PropertyInfo>(type.GetProperties(), p => { pList.Add(p); dt.Columns.Add(p.Name, p.PropertyType); });
foreach (var item in list)
{
//创建一个DataRow实例
DataRow row = dt.NewRow();
//给row 赋值
pList.ForEach(p => row[p.Name] = p.GetValue(item, null));
//加入到DataTable
dt.Rows.Add(row);
}
return dt;
}

/// <summary>
/// 将泛型集合类转换成DataTable

/// </summary>
/// <typeparam name="T">集合项类型</typeparam>

/// <param name="list">集合</param>
/// <returns>数据集(表)</returns>
public static DataTable ToDataTable<T>(IList<T> list)
{
return ToDataTable<T>(list, null);

}

/**/

/// <summary>
/// 将泛型集合类转换成DataTable
/// </summary>
/// <typeparam name="T">集合项类型</typeparam>
/// <param name="list">集合</param>
/// <param name="propertyName">需要返回的列的列名</param>
/// <returns>数据集(表)</returns>
public static DataTable ToDataTable<T>(IList<T> list, params string[] propertyName)
{
List<string> propertyNameList = new List<string>();
if (propertyName != null)
propertyNameList.AddRange(propertyName);
DataTable result = new DataTable();
if (list.Count > 0)
{
PropertyInfo[] propertys = list[0].GetType().GetProperties();
foreach (PropertyInfo pi in propertys)
{
if (propertyNameList.Count == 0)
{
result.Columns.Add(pi.Name, pi.PropertyType);
}
else
{
if (propertyNameList.Contains(pi.Name))
result.Columns.Add(pi.Name, pi.PropertyType);
}
}

for (int i = 0; i < list.Count; i++)
{
ArrayList tempList = new ArrayList();
foreach (PropertyInfo pi in propertys)
{
if (propertyNameList.Count == 0)
{
object obj = pi.GetValue(list[i], null);
tempList.Add(obj);
}
else
{
if (propertyNameList.Contains(pi.Name))
{
object obj = pi.GetValue(list[i], null);
tempList.Add(obj);
}
}
}
object[] array = tempList.ToArray();
result.LoadDataRow(array, true);
}
}
return result;
}
}