C# DataTable 和List之间相互转换的方法
发布者:好饱 ![](http://www.okbase.net/images/site/2010/rk_h0.gif)
![](http://www.okbase.net/images/site/2010/rk_h0.gif)
发布日期:2013-1-27 22:17:49 更新日期:2013-1-27 22:18:55
阅读次数:9554
评分:4.80
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); |