List<T>与DataTable相互转换

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public static class DataTableExtensions

{

/// <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>

/// 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>

/// 将集合类转换成DataTable

/// </summary>

/// <param name="list">集合</param>

/// <returns></returns>

public 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);

}

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

{

ArrayList tempList = new ArrayList();

foreach (PropertyInfo pi in propertys)

{

object obj = pi.GetValue(list[i], null);

tempList.Add(obj);

}

object[] array = tempList.ToArray();

result.LoadDataRow(array, true);

}

}

return result;

}

/**/

/// <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;

}

}