再不用担心DataRow类型转换和空值了（使用扩展方…
2018-06-22 07:08:32来源：未知 阅读 ()
在使用DataRow读取数据时，通常会遇到数据可能为Null, 但是又需要转换为如int等其它类型的数据，因此就通常会写这样的代码：
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!int.TryParse(dr[name].ToString(), out result))
throw new Exception("整形转换失败");
}
而且这样的代码通常会大段大段出现在很多地方。
对于比较懒惰的程序员来说，这样的RY(repeat yourself)是一件很痛苦的事情，因此是时候来想个更好的方法了。这里首先想到的就是Extension Method。
很简单的几句代码，有了这个方法之后，在使用DataRow时，就可以通过扩展方法读取数据了
model.Id = dr.SafeRead<Int32>("Id",0);
model.codeNum = dr.GetString("codeNum");
简单但是实用的代码，希望对大家在项目中有所帮助。
这里参考了,一下两篇文章，并进行了代码重新组织，最后是整理后类源码
使用 Extension Methods 来使 IDataReader 更加方便
C#底层SqlDataReader类常用扩展
public static class SystemDataExtension
{
#region DataReader 扩展
public static T SafeRead<T>(this IDataReader reader, string fieldName, T defaultValue)
{
try
{
object obj = reader[fieldName];
if (obj == null || obj == System.DBNull.Value)
return defaultValue;
return (T)Convert.ChangeType(obj, defaultValue.GetType());
}
catch
{
return defaultValue;
}
}
/// <summary>
/// 获取字符串类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static string GetString(this IDataReader dr, string name)
{
if (dr[name] != DBNull.Value && dr[name] != null)
return dr[name].ToString();
return String.Empty;
}
/// <summary>
/// 获取非空类型数据
/// </summary>
/// <param name="con"></param>
/// <param name="name"></param>
/// <returns></returns>
public static DateTime GetDateTime(this IDataReader dr, string name)
{
DateTime result = DateTime.Now;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!DateTime.TryParse(dr[name].ToString(), out result))
throw new Exception("日期格式数据转换失败");
}
return result;
}
/// <summary>
/// 获取可空类型日期数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static DateTime? GetNullDateTime(this IDataReader dr, string name)
{
DateTime? result = null;
DateTime time = DateTime.Now;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!DateTime.TryParse(dr[name].ToString(), out time))
throw new Exception("日期格式数据转换失败");
result = time;
}
return result;
}
/// <summary>
/// 获取guid类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static Guid GetGuid(this IDataReader dr, string name)
{
Guid guid = Guid.Empty;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (Guid.TryParse(dr[name].ToString(), out guid))
throw new Exception("guid类型数据转换失败");
}
return guid;
}
/// <summary>
/// 获取整形数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static int GetInt32(this IDataReader dr, string name)
{
int result = 0;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!int.TryParse(dr[name].ToString(), out result))
throw new Exception("整形转换失败");
}
return result;
}
/// <summary>
/// 获取双精度类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static double GetDouble(this IDataReader dr, string name)
{
double result = 0.00;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!double.TryParse(dr[name].ToString(), out result))
throw new Exception("双精度类型转换失败");
}
return result;
}
/// <summary>
/// 获取单精度类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static float GetSingle(this IDataReader dr, string name)
{
float result = 0.00f;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!float.TryParse(dr[name].ToString(), out result))
throw new Exception("单精度类型转换失败");
}
return result;
}
/// <summary>
/// 获取decimal类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static decimal GetDecimal(this IDataReader dr, string name)
{
decimal result = 0.00m;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!decimal.TryParse(dr[name].ToString(), out result))
throw new Exception("Decimal类型转换失败");
}
return result;
}
/// <summary>
/// 获取int16类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static Int16 GetInt16(this IDataReader dr, string name)
{
short result = 0;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!short.TryParse(dr[name].ToString(), out result))
throw new Exception("短整形转换失败");
}
return result;
}
/// <summary>
/// 获取Byte类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static byte GetByte(this IDataReader dr, string name)
{
byte result = 0;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!byte.TryParse(dr[name].ToString(), out result))
throw new Exception("Byte类型转换失败");
}
return result;
}
/// <summary>
/// 获取bool类型数据如果传值是1或者是返回true;
/// </summary>
/// <param name="con"></param>
/// <param name="name"></param>
/// <returns></returns>
public static bool GetBool(this IDataReader dr, string name)
{
if (dr[name] != DBNull.Value && dr[name] != null)
{
return dr[name].ToString() == "1" || dr[name].ToString() == "是" || dr[name].ToString().ToLower() == "true";
}
return false;
}
#endregion
#region DataRow 扩展
public static T SafeRead<T>(this DataRow dr, string fieldName, T defaultValue)
{
try
{
object obj = dr[fieldName];
if (obj == null || obj == System.DBNull.Value)
return defaultValue;
return (T)Convert.ChangeType(obj, defaultValue.GetType());
}
catch
{
return defaultValue;
}
}
/// <summary>
/// 获取字符串类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static string GetString(this DataRow dr, string name)
{
if (dr[name] != DBNull.Value && dr[name] != null)
return dr[name].ToString();
return String.Empty;
}
/// <summary>
/// 获取非空类型数据
/// </summary>
/// <param name="con"></param>
/// <param name="name"></param>
/// <returns></returns>
public static DateTime GetDateTime(this DataRow dr, string name)
{
DateTime result = DateTime.Now;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!DateTime.TryParse(dr[name].ToString(), out result))
throw new Exception("日期格式数据转换失败");
}
return result;
}
/// <summary>
/// 获取可空类型日期数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static DateTime? GetNullDateTime(this DataRow dr, string name)
{
DateTime? result = null;
DateTime time = DateTime.Now;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!DateTime.TryParse(dr[name].ToString(), out time))
throw new Exception("日期格式数据转换失败");
result = time;
}
return result;
}
/// <summary>
/// 获取guid类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static Guid GetGuid(this DataRow dr, string name)
{
Guid guid = Guid.Empty;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (Guid.TryParse(dr[name].ToString(), out guid))
throw new Exception("guid类型数据转换失败");
}
return guid;
}
/// <summary>
/// 获取整形数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static int GetInt32(this DataRow dr, string name)
{
int result = 0;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!int.TryParse(dr[name].ToString(), out result))
throw new Exception("整形转换失败");
}
return result;
}
/// <summary>
/// 获取双精度类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static double GetDouble(this DataRow dr, string name)
{
double result = 0.00;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!double.TryParse(dr[name].ToString(), out result))
throw new Exception("双精度类型转换失败");
}
return result;
}
/// <summary>
/// 获取单精度类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static float GetSingle(this DataRow dr, string name)
{
float result = 0.00f;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!float.TryParse(dr[name].ToString(), out result))
throw new Exception("单精度类型转换失败");
}
return result;
}
/// <summary>
/// 获取decimal类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static decimal GetDecimal(this DataRow dr, string name)
{
decimal result = 0.00m;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!decimal.TryParse(dr[name].ToString(), out result))
throw new Exception("Decimal类型转换失败");
}
return result;
}
/// <summary>
/// 获取int16类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static Int16 GetInt16(this DataRow dr, string name)
{
short result = 0;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!short.TryParse(dr[name].ToString(), out result))
throw new Exception("短整形转换失败");
}
return result;
}
/// <summary>
/// 获取Byte类型数据
/// </summary>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
public static byte GetByte(this DataRow dr, string name)
{
byte result = 0;
if (dr[name] != DBNull.Value && dr[name] != null)
{
if (!byte.TryParse(dr[name].ToString(), out result))
throw new Exception("Byte类型转换失败");
}
return result;
}
/// <summary>
/// 获取bool类型数据如果传值是1或者是返回true;
/// </summary>
/// <param name="con"></param>
/// <param name="name"></param>
/// <returns></returns>
public static bool GetBool(this DataRow dr, string name)
{
if (dr[name] != DBNull.Value && dr[name] != null)
{
return dr[name].ToString() == "1" || dr[name].ToString() == "是" || dr[name].ToString().ToLower() == "true";
}
return false;
}
#endregion
}
标签：
版权申明：本站文章部分自网络，如有侵权，请联系：west999com@outlook.com
特别注意：本站所有转载文章言论不代表本站观点，本站所提供的摄影照片，插画，设计作品，如需使用，请与原作者联系，版权归原作者所有
相关文章
- 【推荐】ImageProcessor.Web，再也不用自己生成缩略图了 2018-06-22
- DataSet & DataTable &DataRow 深入浅出 2018-06-22
- DataRow获取数值类型为空或NULL时异常处理 2018-06-22
- DataTable的AcceptChanges()方法和DataRow的RowState属性 2018-06-22
- DataTable转实体Model，DataRow转实体Model，DataTable转泛 2018-06-22
IDC资讯： 主机资讯 注册资讯 托管资讯 vps资讯 网站建设
网站运营： 建站经验 策划盈利 搜索优化 网站推广 免费资源
网络编程： Asp.Net编程 Asp编程 Php编程 Xml编程 Access Mssql Mysql 其它
服务器技术： Web服务器 Ftp服务器 Mail服务器 Dns服务器 安全防护
软件技巧： 其它软件 Word Excel Powerpoint Ghost Vista QQ空间 QQ FlashGet 迅雷
网页制作： FrontPages Dreamweaver Javascript css photoshop fireworks Flash
热门词条
最新资讯
热门关注
热门标签