我有几个返回不同泛型列表的方法。
在 .net 中是否存在将任何列表转换为数据表的类静态方法或其他方法?我唯一能想象的就是使用反射来实现这一点。
如果我有以下内容:
List<Whatever> whatever = new List<Whatever>();
(当然,以下代码不能正常工作,但我希望有这个可能性:
DataTable dt = (DataTable) whatever;
我有几个返回不同泛型列表的方法。
在 .net 中是否存在将任何列表转换为数据表的类静态方法或其他方法?我唯一能想象的就是使用反射来实现这一点。
如果我有以下内容:
List<Whatever> whatever = new List<Whatever>();
(当然,以下代码不能正常工作,但我希望有这个可能性:
DataTable dt = (DataTable) whatever;
Imports System.Reflection
''' <summary>
''' Convert any List(Of T) to a DataTable with correct column types and converts Nullable Type values to DBNull
''' </summary>
Public Class ConvertListToDataset
Public Function ListToDataset(Of T)(ByVal list As IList(Of T)) As DataTable
Dim dt As New DataTable()
'/* Create the DataTable columns */
For Each pi As PropertyInfo In GetType(T).GetProperties()
If pi.PropertyType.IsValueType Then
Debug.Print(pi.Name)
End If
If IsNothing(Nullable.GetUnderlyingType(pi.PropertyType)) Then
dt.Columns.Add(pi.Name, pi.PropertyType)
Else
dt.Columns.Add(pi.Name, Nullable.GetUnderlyingType(pi.PropertyType))
End If
Next
'/* Populate the DataTable with the values in the Items in List */
For Each item As T In list
Dim dr As DataRow = dt.NewRow()
For Each pi As PropertyInfo In GetType(T).GetProperties()
dr(pi.Name) = IIf(IsNothing(pi.GetValue(item)), DBNull.Value, pi.GetValue(item))
Next
dt.Rows.Add(dr)
Next
Return dt
End Function
End Class
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;
}
这里又有一个加入列表:Cinchoo ETL - 一个将可枚举对象转换为数据表格的开源库。
List<Whatever> whatever = new List<Whatever>();
var dt = whatever.AsDataTable();
声明:本库的作者是我。
我认为它更方便易用。
List<Whatever> _lobj= new List<Whatever>();
var json = JsonConvert.SerializeObject(_lobj);
DataTable dt = (DataTable)JsonConvert.DeserializeObject(json, (typeof(DataTable)));
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
private static DataTable ConvertToDataTable<T>(IList<T> data, string[] fieldsToInclude = null,
string[] fieldsToExclude = null)
{
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(typeof(T));
DataTable table = new DataTable();
foreach (PropertyDescriptor prop in properties)
{
if ((fieldsToInclude != null && !fieldsToInclude.Contains(prop.Name)) ||
(fieldsToExclude != null && fieldsToExclude.Contains(prop.Name)))
continue;
table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
}
foreach (T item in data)
{
var atLeastOnePropertyExists = false;
DataRow row = table.NewRow();
foreach (PropertyDescriptor prop in properties)
{
if ((fieldsToInclude != null && !fieldsToInclude.Contains(prop.Name)) ||
(fieldsToExclude != null && fieldsToExclude.Contains(prop.Name)))
continue;
row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
atLeastOnePropertyExists = true;
}
if(atLeastOnePropertyExists) table.Rows.Add(row);
}
if (fieldsToInclude != null)
SetColumnsOrder(table, fieldsToInclude);
return table;
}
private static void SetColumnsOrder(DataTable table, params String[] columnNames)
{
int columnIndex = 0;
foreach (var columnName in columnNames)
{
table.Columns[columnName].SetOrdinal(columnIndex);
columnIndex++;
}
}