将IEnumerable转换为DataTable
有没有一种很好的方法将IEnumerable转换为DataTable？
我可以使用reflection来获得属性和值，但这似乎有点低效，是否有内置的东西？
（我知道这样的例子：ObtainDataTableFromIEnumerable）
编辑 ：
这个问题通知我一个处理空值的问题。
我在下面写的代码正确处理空值。
public static DataTable ToDataTable<T>(this IEnumerable<T> items) { // Create the result table, and gather all properties of a T DataTable table = new DataTable(typeof(T).Name); PropertyInfo[] props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance); // Add the properties as columns to the datatable foreach (var prop in props) { Type propType = prop.PropertyType; // Is it a nullable type? Get the underlying type if (propType.IsGenericType && propType.GetGenericTypeDefinition().Equals(typeof(Nullable<>))) propType = new NullableConverter(propType).UnderlyingType; table.Columns.Add(prop.Name, propType); } // Add the property values per T as rows to the datatable foreach (var item in items) { var values = new object[props.Length]; for (var i = 0; i < props.Length; i++) values[i] = props[i].GetValue(item, null); table.Rows.Add(values); } return table; } 看看这个： 将List / IEnumerable转换为DataTable / DataView
在我的代码中，我将其改为一个扩展方法：
public static DataTable ToDataTable<T>(this List<T> items) { var tb = new DataTable(typeof(T).Name); PropertyInfo[] props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance); foreach(var prop in props) { tb.Columns.Add(prop.Name, prop.PropertyType); } foreach (var item in items) { var values = new object[props.Length]; for (var i=0; i<props.Length; i++) { values[i] = props[i].GetValue(item, null); } tb.Rows.Add(values); } return tb; }
对所有人：
请注意，接受的答案有一个与可空types和DataTable相关的错误。 该修补程序在链接的站点（ http://www.chinhdo.com/20090402/convert-list-to-datatable/ ）或我修改后的代码中可用：
///############################################################### /// <summary> /// Convert a List to a DataTable. /// </summary> /// <remarks> /// Based on MIT-licensed code presented at http://www.chinhdo.com/20090402/convert-list-to-datatable/ as "ToDataTable" /// <para/>Code modifications made by Nick Campbell. /// <para/>Source code provided on this web site (chinhdo.com) is under the MIT license. /// <para/>Copyright © 2010 Chinh Do /// <para/>Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: /// <para/>The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. /// <para/>THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. /// <para/>(As per http://www.chinhdo.com/20080825/transactional-file-manager/) /// </remarks> /// <typeparam name="T">Type representing the type to convert.</typeparam> /// <param name="l_oItems">List of requested type representing the values to convert.</param> /// <returns></returns> ///############################################################### /// <LastUpdated>February 15, 2010</LastUpdated> public static DataTable ToDataTable<T>(List<T> l_oItems) { DataTable oReturn = new DataTable(typeof(T).Name); object[] a_oValues; int i; //#### Collect the a_oProperties for the passed T PropertyInfo[] a_oProperties = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance); //#### Traverse each oProperty, .Add'ing each .Name/.BaseType into our oReturn value //#### NOTE: The call to .BaseType is required as DataTables/DataSets do not support nullable types, so it's non-nullable counterpart Type is required in the .Column definition foreach(PropertyInfo oProperty in a_oProperties) { oReturn.Columns.Add(oProperty.Name, BaseType(oProperty.PropertyType)); } //#### Traverse the l_oItems foreach (T oItem in l_oItems) { //#### Collect the a_oValues for this loop a_oValues = new object[a_oProperties.Length]; //#### Traverse the a_oProperties, populating each a_oValues as we go for (i = 0; i < a_oProperties.Length; i++) { a_oValues[i] = a_oProperties[i].GetValue(oItem, null); } //#### .Add the .Row that represents the current a_oValues into our oReturn value oReturn.Rows.Add(a_oValues); } //#### Return the above determined oReturn value to the caller return oReturn; } ///############################################################### /// <summary> /// Returns the underlying/base type of nullable types. /// </summary> /// <remarks> /// Based on MIT-licensed code presented at http://www.chinhdo.com/20090402/convert-list-to-datatable/ as "GetCoreType" /// <para/>Code modifications made by Nick Campbell. /// <para/>Source code provided on this web site (chinhdo.com) is under the MIT license. /// <para/>Copyright © 2010 Chinh Do /// <para/>Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: /// <para/>The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. /// <para/>THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. /// <para/>(As per http://www.chinhdo.com/20080825/transactional-file-manager/) /// </remarks> /// <param name="oType">Type representing the type to query.</param> /// <returns>Type representing the underlying/base type.</returns> ///############################################################### /// <LastUpdated>February 15, 2010</LastUpdated> public static Type BaseType(Type oType) { //#### If the passed oType is valid, .IsValueType and is logicially nullable, .Get(its)UnderlyingType if (oType != null && oType.IsValueType && oType.IsGenericType && oType.GetGenericTypeDefinition() == typeof(Nullable<>) ) { return Nullable.GetUnderlyingType(oType); } //#### Else the passed oType was null or was not logicially nullable, so simply return the passed oType else { return oType; } }
请注意，这两个例子都不像上面的例子那样是扩展方法。
最后…我的广泛/过多的评论道歉（我有一个肛门/卑鄙的教授，把它打败了我;）
首先你需要添加一个where T:class约束 – 你不能在值types上调用GetValue ，除非它们被ref传递。
其次， GetValue非常缓慢，被调用了很多。
为了解决这个问题，我们可以创build一个委托并调用它：
MethodInfo method = property.GetGetMethod(true); Delegate.CreateDelegate(typeof(Func<TClass, TProperty>), method );
问题是我们不知道TProperty ，但像往常一样在这里Jon Skeet有答案 – 我们可以使用reflection来获取getter委托，但一旦我们有了它，我们不需要再反思：
public class ReflectionUtility { internal static Func<object, object> GetGetter(PropertyInfo property) { // get the get method for the property MethodInfo method = property.GetGetMethod(true); // get the generic get-method generator (ReflectionUtility.GetSetterHelper<TTarget, TValue>) MethodInfo genericHelper = typeof(ReflectionUtility).GetMethod( "GetGetterHelper", BindingFlags.Static | BindingFlags.NonPublic); // reflection call to the generic get-method generator to generate the type arguments MethodInfo constructedHelper = genericHelper.MakeGenericMethod( method.DeclaringType, method.ReturnType); // now call it. The null argument is because it's a static method. object ret = constructedHelper.Invoke(null, new object[] { method }); // cast the result to the action delegate and return it return (Func<object, object>) ret; } static Func<object, object> GetGetterHelper<TTarget, TResult>(MethodInfo method) where TTarget : class // target must be a class as property sets on structs need a ref param { // Convert the slow MethodInfo into a fast, strongly typed, open delegate Func<TTarget, TResult> func = (Func<TTarget, TResult>) Delegate.CreateDelegate(typeof(Func<TTarget, TResult>), method); // Now create a more weakly typed delegate which will call the strongly typed one Func<object, object> ret = (object target) => (TResult) func((TTarget) target); return ret; } }
所以现在你的方法变成：
public static DataTable ToDataTable<T>(this IEnumerable<T> items) where T: class { // ... create table the same way var propGetters = new List<Func<T, object>>(); foreach (var prop in props) { Func<T, object> func = (Func<T, object>) ReflectionUtility.GetGetter(prop); propGetters.Add(func); } // Add the property values per T as rows to the datatable foreach (var item in items) { var values = new object[props.Length]; for (var i = 0; i < props.Length; i++) { //values[i] = props[i].GetValue(item, null); values[i] = propGetters[i](item); } table.Rows.Add(values); } return table; }
您可以通过将每种types的getter存储在一个静态字典中进一步优化它，然后每个types只有一次reflection开销。
我写了一个图书馆来为我处理这个问题。 它被称为DataTableProxy，可作为NuGet包使用 。 代码和文档在Github上
afaik没有任何东西，但是自己build造应该很容易。 我会按照你的build议做，并使用reflection来获取属性，并使用它们来创build表的列。 然后，我将遍历IEnumerable中的每个项目，并为每个项目创build一行。 唯一需要注意的是，如果你的collections包含几种types的物品（比如人物和动物），那么他们可能没有相同的属性。 但如果你需要检查它取决于你的使用。
我通过向IEnumerable添加扩展方法来解决这个问题。
public static class DataTableEnumerate { public static void Fill<T> (this IEnumerable<T> Ts, ref DataTable dt) where T : class { //Get Enumerable Type Type tT = typeof(T); //Get Collection of NoVirtual properties var T_props = tT.GetProperties().Where(p => !p.GetGetMethod().IsVirtual).ToArray(); //Fill Schema foreach (PropertyInfo p in T_props) dt.Columns.Add(p.Name, p.GetMethod.ReturnParameter.ParameterType.BaseType); //Fill Data foreach (T t in Ts) { DataRow row = dt.NewRow(); foreach (PropertyInfo p in T_props) row[p.Name] = p.GetValue(t); dt.Rows.Add(row); } } }
