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IEnumerable을 DataTable로 변환
IEnumerable을 DataTable로 변환하는 좋은 방법이 있습니까?
리플렉션을 사용하여 속성과 값을 얻을 수 있지만 약간 비효율적으로 보입니다. 내장 된 것이 있습니까?
(예 : ObtainDataTableFromIEnumerable)
편집 :
이 질문 은 null 값을 처리하는 데 문제가 있음을 알 렸습니다.
아래에 작성한 코드는 null 값을 올바르게 처리합니다.
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;
}
이것 좀 봐 : List / IEnumerable을 DataTable / DataView로 변환
내 코드에서 확장 메서드로 변경했습니다.
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;
}
모든:
허용되는 답변에는 nullable 형식 및 DataTable과 관련된 버그가 있습니다. 수정 사항은 링크 된 사이트 ( http://www.chinhdo.com/20090402/convert-list-to-datatable/ ) 또는 아래 수정 된 코드에서 사용할 수 있습니다.
///###############################################################
/// <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;
}
}
이 두 예는 위의 예와 같은 확장 메서드 가 아닙니다 .
마지막으로 ... 내 광범위한 / 과도한 댓글에 대해 사과드립니다 (항문 / 평균 교수가 나를 때렸습니다!;)
나는 이것을 처리하기 위해 도서관을 작성했습니다. DataTableProxy라고하며 NuGet 패키지 로 제공됩니다 . 코드 및 문서는 Github에 있습니다.
먼저 where T:class제약 조건 을 추가해야합니다 . GetValue.NET에서 전달되지 않는 한 값 유형을 호출 할 수 없습니다 ref.
둘째, GetValue매우 느리고 많이 호출됩니다.
이 문제를 해결하기 위해 대리자를 만들고 대신 호출 할 수 있습니다.
MethodInfo method = property.GetGetMethod(true);
Delegate.CreateDelegate(typeof(Func<TClass, TProperty>), method );
문제는 우리가 알지 못한다 TProperty는 것입니다.하지만 평소와 같이 Jon Skeet가 답을 가지고 있습니다. 리플렉션을 사용하여 getter 델리게이트를 검색 할 수 있지만 일단 다시 반영 할 필요가 없습니다.
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;
}
}
이제 방법은 다음과 같습니다.
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;
}
정적 사전에 각 유형에 대한 게터를 저장하여 추가로 최적화 할 수 있으며, 그러면 각 유형에 대해 한 번만 리플렉션 오버 헤드가 발생합니다.
There is nothing built in afaik, but building it yourself should be easy. I would do as you suggest and use reflection to obtain the properties and use them to create the columns of the table. Then I would step through each item in the IEnumerable and create a row for each. The only caveat is if your collection contains items of several types (say Person and Animal) then they may not have the same properties. But if you need to check for it depends on your use.
I solve this problem by adding extension method to IEnumerable.
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);
}
}
}
I also came across this problem. In my case, I didn't know the type of the IEnumerable. So the answers given above wont work. However, I solved it like this:
public static DataTable CreateDataTable(IEnumerable source)
{
var table = new DataTable();
int index = 0;
var properties = new List<PropertyInfo>();
foreach (var obj in source)
{
if (index == 0)
{
foreach (var property in obj.GetType().GetProperties())
{
if (Nullable.GetUnderlyingType(property.PropertyType) != null)
{
continue;
}
properties.Add(property);
table.Columns.Add(new DataColumn(property.Name, property.PropertyType));
}
}
object[] values = new object[properties.Count];
for (int i = 0; i < properties.Count; i++)
{
values[i] = properties[i].GetValue(obj);
}
table.Rows.Add(values);
index++;
}
return table;
}
Keep in mind that using this method, requires at least one item in the IEnumerable. If that's not the case, the DataTable wont create any columns.
So, 10 years later this is still a thing :)
I've tried every answer on this page (ATOW)
and also some ILGenerator powered solutions (FastMember and Fast.Reflection).
But a compiled Lambda Expression seems to be the fastest.
At least for my use cases (on .Net Core 2.2).
This is what I am using for now:
public static class EnumerableExtensions {
internal static Func<TClass, object> CompileGetter<TClass>(string propertyName) {
var param = Expression.Parameter(typeof(TClass));
var body = Expression.Convert(Expression.Property(param, propertyName), typeof(object));
return Expression.Lambda<Func<TClass, object>>(body,param).Compile();
}
public static DataTable ToDataTable<T>(this IEnumerable<T> collection) {
var dataTable = new DataTable();
var properties = typeof(T)
.GetProperties(BindingFlags.Public | BindingFlags.Instance)
.Where(p => p.CanRead)
.ToArray();
if (properties.Length < 1) return null;
var getters = new Func<T, object>[properties.Length];
for (var i = 0; i < properties.Length; i++) {
var columnType = Nullable.GetUnderlyingType(properties[i].PropertyType) ?? properties[i].PropertyType;
dataTable.Columns.Add(properties[i].Name, columnType);
getters[i] = CompileGetter<T>(properties[i].Name);
}
foreach (var row in collection) {
var dtRow = new object[properties.Length];
for (var i = 0; i < properties.Length; i++) {
dtRow[i] = getters[i].Invoke(row) ?? DBNull.Value;
}
dataTable.Rows.Add(dtRow);
}
return dataTable;
}
}
Only works with properties (not fields) but it works on Anonymous Types.
A 2019 answer if you're using .NET Core - use the Nuget ToDataTable library. Advantages:
- Better performance than reflection or using DataTableProxy
- Also creates SqlParameters for use with SQL Server Table-Valued Parameters
Disclaimer - I'm the author of ToDataTable
Performance - I span up some Benchmark .Net tests and included them in the ToDataTable repo. The results were as follows:
Creating a 100,000 Row Datatable:
Reflection 818.5 ms
DataTableProxy 1,068.8 ms
ToDataTable 449.0 ms
참고URL : https://stackoverflow.com/questions/1253725/convert-ienumerable-to-datatable
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