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

  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;
    }
}

其他回答

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

这是一个简单的控制台应用程序,用于将列表转换为数据表。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.ComponentModel;

namespace ConvertListToDataTable
{
    public static class Program
    {
        public static void Main(string[] args)
        {
            List<MyObject> list = new List<MyObject>();
            for (int i = 0; i < 5; i++)
            {
                list.Add(new MyObject { Sno = i, Name = i.ToString() + "-KarthiK", Dat = DateTime.Now.AddSeconds(i) });
            }

            DataTable dt = ConvertListToDataTable(list);
            foreach (DataRow row in dt.Rows)
            {
                Console.WriteLine();
                for (int x = 0; x < dt.Columns.Count; x++)
                {
                    Console.Write(row[x].ToString() + " ");
                }
            }
            Console.ReadLine();
        }

        public class MyObject
        {
            public int Sno { get; set; }
            public string Name { get; set; }
            public DateTime Dat { get; set; }
        }

        public static DataTable ConvertListToDataTable<T>(this List<T> iList)
        {
            DataTable dataTable = new DataTable();
            PropertyDescriptorCollection props = TypeDescriptor.GetProperties(typeof(T));
            for (int i = 0; i < props.Count; i++)
            {
                PropertyDescriptor propertyDescriptor = props[i];
                Type type = propertyDescriptor.PropertyType;

                if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
                    type = Nullable.GetUnderlyingType(type);

                dataTable.Columns.Add(propertyDescriptor.Name, type);
            }
            object[] values = new object[props.Count];
            foreach (T iListItem in iList)
            {
                for (int i = 0; i < values.Length; i++)
                {
                    values[i] = props[i].GetValue(iListItem);
                }
                dataTable.Rows.Add(values);
            }
            return dataTable;
        }
    }
}
List<object> Basket;

string json = JsonConvert.SerializeObject(Basket, Formatting.Indented);
DataTable dtUsingMethod = Business.GetJSONToDataTableUsingNewtonSoftDll(json);



public static DataTable GetJSONToDataTableUsingNewtonSoftDll(string JSONData)
{
    DataTable dt = (DataTable)JsonConvert.DeserializeObject(JSONData, (typeof(DataTable)));
    return dt;
}

您可以尝试以下内容

public static DataTable GetDataTableFromObjects(object[] objects)
{
    if (objects != null && objects.Length > 0)
    {
        Type t = objects[0].GetType();
        DataTable dt = new DataTable(t.Name);
        foreach (PropertyInfo pi in t.GetProperties())
        {
            dt.Columns.Add(new DataColumn(pi.Name));
        }
        foreach (var o in objects)
        {
            DataRow dr = dt.NewRow();
            foreach (DataColumn dc in dt.Columns)
            {
                dr[dc.ColumnName] = o.GetType().GetProperty(dc.ColumnName).GetValue(o, null);
            }
            dt.Rows.Add(dr);
        }
        return dt;
    }
    return null;
}
 Dim counties As New List(Of County)
 Dim dtCounties As DataTable
 dtCounties = _combinedRefRepository.Get_Counties()
 If dtCounties.Rows.Count <> 0 Then
    For Each row As DataRow In dtCounties.Rows
      Dim county As New County
      county.CountyId = row.Item(0).ToString()
      county.CountyName = row.Item(1).ToString().ToUpper()
      counties.Add(county)
    Next
    dtCounties.Dispose()
 End If