我有几个方法返回不同的泛型列表。
在。net中存在任何类静态方法或将任何列表转换为数据表?我唯一能想到的是使用反射来做到这一点。
如果我有这个:
List<Whatever> whatever = new List<Whatever>();
(这下代码当然不工作,但我想有这样的可能性:
DataTable dt = (DataTable) whatever;
我有几个方法返回不同的泛型列表。
在。net中存在任何类静态方法或将任何列表转换为数据表?我唯一能想到的是使用反射来做到这一点。
如果我有这个:
List<Whatever> whatever = new List<Whatever>();
(这下代码当然不工作,但我想有这样的可能性:
DataTable dt = (DataTable) whatever;
当前回答
要将泛型列表转换为数据表,可以使用DataTableGenerator
这个库允许您将列表转换为具有多种功能的数据表,如
翻译数据表头 指定要显示的列
其他回答
It's also possible through XmlSerialization.
The idea is - serialize to `XML` and then `readXml` method of `DataSet`.
I use this code (from an answer in SO, forgot where)
public static string SerializeXml<T>(T value) where T : class
{
if (value == null)
{
return null;
}
XmlSerializer serializer = new XmlSerializer(typeof(T));
XmlWriterSettings settings = new XmlWriterSettings();
settings.Encoding = new UnicodeEncoding(false, false);
settings.Indent = false;
settings.OmitXmlDeclaration = false;
// no BOM in a .NET string
using (StringWriter textWriter = new StringWriter())
{
using (XmlWriter xmlWriter = XmlWriter.Create(textWriter, settings))
{
serializer.Serialize(xmlWriter, value);
}
return textWriter.ToString();
}
}
so then it's as simple as:
string xmlString = Utility.SerializeXml(trans.InnerList);
DataSet ds = new DataSet("New_DataSet");
using (XmlReader reader = XmlReader.Create(new StringReader(xmlString)))
{
ds.Locale = System.Threading.Thread.CurrentThread.CurrentCulture;
ds.ReadXml(reader);
}
Not sure how it stands against all the other answers to this post, but it's also a possibility.
我认为它更方便和容易使用。
List<Whatever> _lobj= new List<Whatever>();
var json = JsonConvert.SerializeObject(_lobj);
DataTable dt = (DataTable)JsonConvert.DeserializeObject(json, (typeof(DataTable)));
我意识到这里已经关门有一段时间了;然而,我有一个解决这个特定问题的解决方案,但需要稍微扭转:列和数据表需要预先定义/已经实例化。然后我只需将类型插入到数据表中。
下面是我所做的一个例子:
public static class Test
{
public static void Main()
{
var dataTable = new System.Data.DataTable(Guid.NewGuid().ToString());
var columnCode = new DataColumn("Code");
var columnLength = new DataColumn("Length");
var columnProduct = new DataColumn("Product");
dataTable.Columns.AddRange(new DataColumn[]
{
columnCode,
columnLength,
columnProduct
});
var item = new List<SomeClass>();
item.Select(data => new
{
data.Id,
data.Name,
data.SomeValue
}).AddToDataTable(dataTable);
}
}
static class Extensions
{
public static void AddToDataTable<T>(this IEnumerable<T> enumerable, System.Data.DataTable table)
{
if (enumerable.FirstOrDefault() == null)
{
table.Rows.Add(new[] {string.Empty});
return;
}
var properties = enumerable.FirstOrDefault().GetType().GetProperties();
foreach (var item in enumerable)
{
var row = table.NewRow();
foreach (var property in properties)
{
row[property.Name] = item.GetType().InvokeMember(property.Name, BindingFlags.GetProperty, null, item, null);
}
table.Rows.Add(row);
}
}
}
我自己编写了一个小型库来完成这个任务。它只在将对象类型转换为数据表时第一次使用反射。它发出一个方法,该方法将完成转换对象类型的所有工作。
它燃烧得很快。你可以在这里找到它:
ToDataTable()在MoreLinq上的GitHub 原:ModelShredder在GoogleCode,被合并到MoreLinq,从GoogleCode移动到GitHub
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.ComponentModel;
public partial class Default3 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
DataTable dt = new DataTable();
dt = lstEmployee.ConvertToDataTable();
}
public static DataTable ConvertToDataTable<T>(IList<T> list) where T : class
{
try
{
DataTable table = CreateDataTable<T>();
Type objType = typeof(T);
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(objType);
foreach (T item in list)
{
DataRow row = table.NewRow();
foreach (PropertyDescriptor property in properties)
{
if (!CanUseType(property.PropertyType)) continue;
row[property.Name] = property.GetValue(item) ?? DBNull.Value;
}
table.Rows.Add(row);
}
return table;
}
catch (DataException ex)
{
return null;
}
catch (Exception ex)
{
return null;
}
}
private static DataTable CreateDataTable<T>() where T : class
{
Type objType = typeof(T);
DataTable table = new DataTable(objType.Name);
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(objType);
foreach (PropertyDescriptor property in properties)
{
Type propertyType = property.PropertyType;
if (!CanUseType(propertyType)) continue;
//nullables must use underlying types
if (propertyType.IsGenericType && propertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
propertyType = Nullable.GetUnderlyingType(propertyType);
//enums also need special treatment
if (propertyType.IsEnum)
propertyType = Enum.GetUnderlyingType(propertyType);
table.Columns.Add(property.Name, propertyType);
}
return table;
}
private static bool CanUseType(Type propertyType)
{
//only strings and value types
if (propertyType.IsArray) return false;
if (!propertyType.IsValueType && propertyType != typeof(string)) return false;
return true;
}
}