将DataTable转换为List [英] Convert DataTable to List
本文介绍了将DataTable转换为List的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
您好，
任务：将数据表转换为列表
到目前为止，我有使用EnumerableRowCollection< trow>完成此操作。代码如下：
Hello,
Task: To convert an DataTable To List
So far, I have done this using EnumerableRowCollection<trow>. and the code goes as below:
private void LoadAppointments()
{
var conn = new SqlConnection(ConnectionString);
var adapter = new SqlDataAdapter("LoadAppointment", conn);
var ds = new DataSet();
adapter.Fill(ds);
var myData = ds.Tables[0].AsEnumerable().Select(r => new
{
column1 = r.Field<int>("AppointmentId"),
column2 = r.Field<string>("Subject"),
column3 = r.Field<DateTime>("StartDate"),
column4 = r.Field<DateTime>("EndDate"),
column5 = r.Field<bool>("AllDay"),
column6 = r.Field<int>("Status"),
column7= r.Field<int>("Label"),
column8 = r.Field<string>("CustomName"),
column9 = r.Field<string>("CustomName")
});
var list = myData.ToList();
schedulerStorage1.Appointments.DataSource = list;
}
但是，我有一个带有一些属性的Custom类。我想创建该类的列表，而不是使用EnumerableRowCollection< trow>。
更具体一点：我想选择EnumerableRowCollection< trow>以外的替代方式。
任何关于此的帮助都将受到很多赞赏!!
But, I have a Custom class with some properties. I would like to Create a list out of that class instead of using EnumerableRowCollection<trow>.
To be more specific: I would like to go for an alternative way other than EnumerableRowCollection<trow>.
Any help regarding this will be appreciated a lot!!
推荐答案
阅读本文：使用实体而不是DataTable对象...... [ ^ ]
选择时可以提供您想要结果的类型并相应地填充属性。如果您没有提供，则默认情况下会创建AnonymousType。请在此处的示例代码中查看，我将获得员工列表作为输出：
While selecting you can provide the type you want the result in and fill the properties accordingly. If you don't provide then by default it creates AnonymousType. See it in the sample code here where i am getting a list of employees as output:
public void datatest() {
DataTable dt = new DataTable("table1");
dt.Columns.Add("name");
dt.Columns.Add("Role");
dt.Rows.Add("rama", "god");
dt.Rows.Add("krishna", "god");
dt.Rows.Add("ravana", "devil");
List<emp> output = dt.AsEnumerable().Select(r => new Emp() { Name = r.Field<string>("name"), Role = r.Field<string>("Role") }).ToList();
}
}
class Emp
{
public string Name = string.Empty;
public string Role = string.Empty;
}
将数据表转换为列表的常用类
A common class for convert datatable to list
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
namespace BL
{
public class clsCommonFunctions
{
}
public static class Helper
{
public static List<T> DataTableToList<T>(this DataTable dataTable) where T : new()
{
var dataList = new List<T>();
//Define what attributes to be read from the class
const System.Reflection.BindingFlags flags = System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance;
//Read Attribute Names and Types
var objFieldNames = typeof(T).GetProperties(flags).Cast<System.Reflection.PropertyInfo>().
Select(item => new
{
Name = item.Name,
Type = Nullable.GetUnderlyingType(item.PropertyType) ?? item.PropertyType
}).ToList();
//Read Datatable column names and types
var dtlFieldNames = dataTable.Columns.Cast<DataColumn>().
Select(item => new
{
Name = item.ColumnName,
Type = item.DataType
}).ToList();
foreach (DataRow dataRow in dataTable.AsEnumerable().ToList())
{
var classObj = new T();
foreach (var dtField in dtlFieldNames)
{
System.Reflection.PropertyInfo propertyInfos = classObj.GetType().GetProperty(dtField.Name);
var field = objFieldNames.Find(x => x.Name == dtField.Name);
if (field != null)
{
if (propertyInfos.PropertyType == typeof(DateTime))
{
propertyInfos.SetValue
(classObj, convertToDateTime(dataRow[dtField.Name]), null);
}
else if (propertyInfos.PropertyType == typeof(Nullable<DateTime>))
{
propertyInfos.SetValue
(classObj, convertToDateTime(dataRow[dtField.Name]), null);
}
else if (propertyInfos.PropertyType == typeof(int))
{
propertyInfos.SetValue
(classObj, ConvertToInt(dataRow[dtField.Name]), null);
}
else if (propertyInfos.PropertyType == typeof(long))
{
propertyInfos.SetValue
(classObj, ConvertToLong(dataRow[dtField.Name]), null);
}
else if (propertyInfos.PropertyType == typeof(decimal))
{
propertyInfos.SetValue
(classObj, ConvertToDecimal(dataRow[dtField.Name]), null);
}
else if (propertyInfos.PropertyType == typeof(String))
{
if (dataRow[dtField.Name].GetType() == typeof(DateTime))
{
propertyInfos.SetValue
(classObj, ConvertToDateString(dataRow[dtField.Name]), null);
}
else
{
propertyInfos.SetValue
(classObj, ConvertToString(dataRow[dtField.Name]), null);
}
}
}
}
dataList.Add(classObj);
}
return dataList;
}
private static string ConvertToDateString(object date)
{
if (date == null)
return string.Empty;
return date == null ? string.Empty : Convert.ToDateTime(date).ConvertDate();
}
private static string ConvertToString(object value)
{
return Convert.ToString(ReturnEmptyIfNull(value));
}
private static int ConvertToInt(object value)
{
return Convert.ToInt32(ReturnZeroIfNull(value));
}
private static long ConvertToLong(object value)
{
return Convert.ToInt64(ReturnZeroIfNull(value));
}
private static decimal ConvertToDecimal(object value)
{
return Convert.ToDecimal(ReturnZeroIfNull(value));
}
private static DateTime convertToDateTime(object date)
{
return Convert.ToDateTime(ReturnDateTimeMinIfNull(date));
}
public static string ConvertDate(this DateTime datetTime, bool excludeHoursAndMinutes = false)
{
if (datetTime != DateTime.MinValue)
{
if (excludeHoursAndMinutes)
return datetTime.ToString("yyyy-MM-dd");
return datetTime.ToString("yyyy-MM-dd HH:mm:ss.fff");
}
return null;
}
public static object ReturnEmptyIfNull(this object value)
{
if (value == DBNull.Value)
return string.Empty;
if (value == null)
return string.Empty;
return value;
}
public static object ReturnZeroIfNull(this object value)
{
if (value == DBNull.Value)
return 0;
if (value == null)
return 0;
return value;
}
public static object ReturnDateTimeMinIfNull(this object value)
{
if (value == DBNull.Value)
return DateTime.MinValue;
if (value == null)
return DateTime.MinValue;
return value;
}
}
}
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