FieldConverter ConverterKind.Date" DD / MM / YYYY"例外

问题描述

我尝试读取csv文件。
我的第五个记录contans日期：2008年3月11日

I try to read a csv file.my fifth record contans a date: 03/11/2008

这是一段我的代码：

    [FieldConverter(ConverterKind.Date, "dd/MM/yyyy")]
    public DateTime datum_5;

在此我的代码crashs：

My code crashs on this:

Result[] results= (Result[])engine.ReadFile(@"..\Data\expo.txt");

和与此异常：
线：1列：41现场：datum_5。错误转换'03 / 11/2008'的键入：日期时间。使用格式：'DD / MM / YYYY

And with this exception:Line: 1. Column: 41. Field: datum_5. Error Converting '03/11/2008' to type: 'DateTime'. Using the format: 'dd/MM/yyyy'

当我这样做：

[FieldConverter(typeof(ConvertDate))]

        public DateTime datum_5;

与此：

with this:

internal class ConvertDate : ConverterBase
   {

       /// <summary>
       /// different forms for date separator : . or / or space
       /// </summary>
       /// <param name="from">the string format of date - first the day</param>
       /// <returns></returns>

       public override object StringToField(string from)
       {
           DateTime dt;

           if (DateTime.TryParseExact(from, "dd.MM.yyyy", null, DateTimeStyles.None, out dt))
               return dt;

           if (DateTime.TryParseExact(from, "dd/MM/yyyy", null, DateTimeStyles.None, out dt))
               return dt;

           if (DateTime.TryParseExact(from, "dd MM yyyy", null, DateTimeStyles.None, out dt))
               return dt;

           throw new ArgumentException("can not make a date from " + from, "from");

       }
   }

我得到这个异常：不能从做2008年3月11日
Parameternaam日期：从

I got this exception: can not make a date from 03/11/2008Parameternaam: from

我究竟做错了

推荐答案

它的失败的原因是，/在一个自定义日期格式字符串的描述。

The reason it's failing is that / in a custom date format string is a culture-specific DateSeparator as described in MSDN.

您指定空为的IFormatProvider 参数，所以它使用目前的文化，这大概比/.

You are specifying null for the IFormatProvider argument, so it's using the current culture, which presumably has a date separator other than /.

最好的办法是明确指定CultureInfo.InvariantCulture（下图2版）。逃离'/'在您的自定义日期格式的字符串，使其作为文字斜杠，而不是DateSeparator也将工作（下一个版本）进行处理。

The best solution is to explicitly specify CultureInfo.InvariantCulture (second version below). Escaping the '/' in your custom date format string so that it is treated as a literal slash rather than a DateSeparator will also work (first version below).

// Set current culture to a culture that uses "." as DateSeparator
Thread.CurrentThread.CurrentCulture = new CultureInfo("de-DE");
// This will work - escaping means it uses a literal / as the separator
DateTime.TryParseExact(s, @"dd\/MM\/yyyy", null, DateTimeStyles.None, out result);

// This is better - Culture.InvariantCulture uses / for the DateTimeFormatInfo.DateSeparator
// and you clearly express the intent to use the invariant culture
DateTime.TryParseExact(s, "dd/MM/yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out result);

// This will fail - / means use DateTimeFormatInfo.DateSeparator which is "." in the de-DE culture
DateTime.TryParseExact(s, "dd/MM/yyyy", null, DateTimeStyles.None, out result);

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