有时候我们需要将sql查询返回的DataTable转换为类。最开始是使用循环一个个给类的属性赋值，但是这样效率低并且无法复用。
后来了解到利用DataTable添加扩展方法可以轻松的实现这一功能
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将DataTable转化为List,使用DataTable.ToList();
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将DataTable转化为,使用DataTable.ToData();
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填充已有内容,使用DataTable.FillData();
注：
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ConvertHelper类请参考 https://www.cnblogs.com/axiaoshuye/articles/15697734.html
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转换的前提条件是DataTable字段名要与对应类的属性名一致
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace DataTableEx
{
public static class DataTableEx
{
public static List<T> ToList<T>(this DataTable dt) where T : new()
{
List<T> ts = new List<T>();
foreach (DataRow dr in dt.Rows)
{
T t = new T();
foreach (var c in dt.Columns)
{
object value = dr[c.ToString()];
if (value != DBNull.Value)
{
var p = t.GetType().GetProperty(c.ToString());
if (p != null)
{
p.SetValue(t, ConvertHelper.ChangeType(value, p.PropertyType), null);
}
}
}
ts.Add(t);
}
return ts;
}
public static T ToData<T>(this DataTable dt) where T : new()
{
if (dt.Rows.Count>1)
{
throw new Exception("");
}
List<T> ts = new List<T>();
foreach (DataRow dr in dt.Rows)
{
T t = new T();
foreach (var c in dt.Columns)
{
object value = dr[c.ToString()];
if (value != DBNull.Value)
{
var p = t.GetType().GetProperty(c.ToString());
if (p != null)
{
p.SetValue(t, ConvertHelper.ChangeType(value, p.PropertyType), null);
}
}
}
return t;
}
return default(T);
}
public static void FillData<T>(this DataTable dt,ref T t) where T : new()
{
if (dt.Rows.Count > 1)
{
throw new Exception("");
}
foreach (DataRow dr in dt.Rows)
{
foreach (var c in dt.Columns)
{
object value = dr[c.ToString()];
if (value != DBNull.Value)
{
var p = t.GetType().GetProperty(c.ToString());
if (p != null)
{
p.SetValue(t, ConvertHelper.ChangeType(value, p.PropertyType), null);
}
}
}
}
}
}
public static class ConvertHelper
{
#region = ChangeType =
public static object ChangeType(object obj, Type conversionType)
{
return ChangeType(obj, conversionType, System.Threading.Thread.CurrentThread.CurrentCulture);
}
public static object ChangeType(object obj, Type conversionType, IFormatProvider provider)
{
#region Nullable
Type nullableType = Nullable.GetUnderlyingType(conversionType);
if (nullableType != null)
{
if (obj == null)
{
return null;
}
return Convert.ChangeType(obj, nullableType, provider);
}
#endregion
if (typeof(System.Enum).IsAssignableFrom(conversionType))
{
return Enum.Parse(conversionType, obj.ToString());
}
return Convert.ChangeType(obj, conversionType, provider);
}
#endregion
}
}