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我们在项目中经常会使用到　List 转为　DataTable

方法一．　通过 扩展方法的方式，写一个IList接口的扩展方法

using System;using System.Collections.Generic;using System.Data;using System.ComponentModel;namespace DocumentSearch{
       public static class DataTableExtensions    {
           public static DataTable ToDataTable
   
    (this IList
    
      data)        {
               PropertyDescriptorCollection properties =                TypeDescriptor.GetProperties(typeof(T));            DataTable table = new DataTable();            foreach (PropertyDescriptor prop in properties)                table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);            foreach (T item in data)            {
                   DataRow row = table.NewRow();                foreach (PropertyDescriptor prop in properties)                    row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;                table.Rows.Add(row);            }            return table;        }    }}调用时：var users = dbContext.Users.ToList().ToDataTable();或var users = dbContext.Users.ToListAsync().Result.ToDataTable();注意：用异步转为list,则要等 有result后再转为 datatable.
    
   

方法二．写一个自定义的类

using System;using System.Collections;using System.Collections.Generic;using System.Linq;using System.Text;using System.Data;using System.Reflection;using System.ComponentModel;namespace DotNet.Utilities{
       /// 
    /// IList 公共帮助类    /// 
    public class IListHelper    {
           /// 
        /// IList如何转成List
    
             /// 
    
        /// 
           ///         /// 
           public static List
   
     IListToList
    
     (IList list)        {
               T[] array = new T[list.Count];            list.CopyTo(array, 0);            return new List
     
      (array);        }        /// 
      
        /// Convert a List{T} to a DataTable.        /// 
        public static DataTable ToDataTable
      
       (List
       
         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;        }        /// 
        
 /// Determine of specified type is nullable /// 
        public static bool IsNullable(Type t)        {
               return !t.IsValueType || (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Nullable<>));        }        /// 
        
 /// Return underlying type if type is Nullable otherwise return the type /// 
        public static Type GetCoreType(Type t)        {
               if (t != null && IsNullable(t))            {
                   if (!t.IsValueType)                {
                       return t;                }                else                {
                       return Nullable.GetUnderlyingType(t);                }            }            else            {
                   return t;            }        }        public static DataTable ToDataTable
        
         (IList
         
           data) { PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(typeof(T)); DataTable table = new DataTable(); foreach (PropertyDescriptor prop in properties) table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType); foreach (T item in data) { DataRow row = table.NewRow(); foreach (PropertyDescriptor prop in properties) row[prop.Name] = prop.GetValue(item) ?? DBNull.Value; table.Rows.Add(row); } return table; } }}
         
        
       
      
     
    
   

ＶＢ：

Imports System.DataImports System.CollectionsImports System.Reflection' 
' IList 公共帮助类' 
Public Class IListHelper    ''' 
    ''' Convert a DataGridView to DataTable    ''' 
    '''     ''' 
       Public Function ToDataTable(ByVal dgv As DataGridView) As DataTable        Dim tb = New DataTable(dgv.Name)        'Add table column        For Each col In dgv.Columns.OfType(Of DataGridViewColumn)            tb.Columns.Add(col.HeaderText)        Next        'Content        For Each dgvrow In dgv.Rows.OfType(Of DataGridViewRow)            Dim datarow = tb.NewRow()            For Each col In dgv.Columns.OfType(Of DataGridViewColumn)                datarow(col.Name) = Convert.ToString(dgvrow.Cells(col.Name).Value)            Next            tb.Rows.Add(datarow)        Next        Return tb    End Function    ' 
    ' Convert a List{T} to a DataTable.    ' 
    Public Function ToDataTable(Of T)(ByVal items As List(Of T)) As DataTable        Dim tb = New DataTable(GetType(T).Name)        Dim props As PropertyInfo() = GetType(T).GetProperties(BindingFlags.Public OrElse BindingFlags.Instance)        For Each prop As PropertyInfo In props            'Type T = GetCoreType(prop.PropertyType)            tb.Columns.Add(prop.Name, GetCoreType(prop.PropertyType))        Next        For Each item In items            Dim values(props.Length - 1) As Object            For i = 0 To props.Length - 1                values(i) = props(i).GetValue(item)            Next            tb.Rows.Add(values)        Next        Return tb    End Function    ' 
    ' Determine of specified type Is nullable    ' 
    Public Function IsNullable(ByVal t As Type) As Boolean        Return Not t.IsValueType 'Or (t.IsGenericType And t.GetGenericTypeDefinition() = GetType(Nullable()))    End Function    ' 
    ' Return underlying type if type Is Nullable otherwise return the type    ' 
    Public Function GetCoreType(ByVal t As Type) As Type        If t <> Nothing And IsNullable(t) Then            If (Not t.IsValueType) Then                Return t            Else                Return Nullable.GetUnderlyingType(t)            End If        Else            Return t        End If    End FunctionEnd Class

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