Question

我想知道如何在filehelpers中执行多个日期？看来你必须指定你要支持的每种格式（有点糟糕......希望它可以处理更多基本格式）。

   [FieldOrder(1), FieldConverter(ConverterKind.DateMultiFormat, "MM/dd/yyyy", "MM/d/yyyy", "M/d/yyyy","M/dd/yyyy")]

这给了我但是

Error   35  Argument 1: cannot convert from 'FileHelpers.ConverterKind' to 'System.Type'

所以看来我必须做一些自定义转换或什么？这是对的吗？

修改

我使用的是版本2.9.9.0

选项

// Summary:
//     Indicates the FileHelpers.ConverterKind used for read/write operations.
//
// Remarks:
//     See the Complete attributes list for more information and examples of each
//     one.
[AttributeUsage(AttributeTargets.Field)]
public sealed class FieldConverterAttribute : Attribute
{
    // Summary:
    //     Indicates the FileHelpers.ConverterKind used for read/write operations.
    //
    // Parameters:
    //   converter:
    //     The FileHelpers.ConverterKind used for the transformations.
    public FieldConverterAttribute(ConverterKind converter);
    //
    // Summary:
    //     Indicates a custom FileHelpers.ConverterBase implementation.
    //
    // Parameters:
    //   customConverter:
    //     The Type of your custom converter.
    public FieldConverterAttribute(Type customConverter);
    //
    // Summary:
    //     Indicates the FileHelpers.ConverterKind used for read/write operations.
    //
    // Parameters:
    //   converter:
    //     The FileHelpers.ConverterKind used for the transformations.
    //
    //   arg1:
    //     The first param passed directly to the Converter Constructor.
    public FieldConverterAttribute(ConverterKind converter, string arg1);
    //
    // Summary:
    //     Indicates a custom FileHelpers.ConverterBase implementation.
    //
    // Parameters:
    //   customConverter:
    //     The Type of your custom converter.
    //
    //   args:
    //     A list of params passed directly to your converter constructor.
    public FieldConverterAttribute(Type customConverter, params object[] args);
    //
    // Summary:
    //     Indicates a custom FileHelpers.ConverterBase implementation.
    //
    // Parameters:
    //   customConverter:
    //     The Type of your custom converter.
    //
    //   arg1:
    //     The first param passed directly to the Converter Constructor.
    public FieldConverterAttribute(Type customConverter, string arg1);
    //
    // Summary:
    //     Indicates the FileHelpers.ConverterKind used for read/write operations.
    //
    // Parameters:
    //   converter:
    //     The FileHelpers.ConverterKind used for the transformations.
    //
    //   arg1:
    //     The first param passed directly to the Converter Constructor.
    //
    //   arg2:
    //     The second param passed directly to the Converter Constructor.
    public FieldConverterAttribute(ConverterKind converter, string arg1, string arg2);
    //
    // Summary:
    //     Indicates a custom FileHelpers.ConverterBase implementation.
    //
    // Parameters:
    //   customConverter:
    //     The Type of your custom converter.
    //
    //   arg1:
    //     The first param passed directly to the Converter Constructor.
    //
    //   arg2:
    //     The second param passed directly to the Converter Constructor.
    public FieldConverterAttribute(Type customConverter, string arg1, string arg2);
    //
    // Summary:
    //     Indicates the FileHelpers.ConverterKind used for read/write operations.
    //
    // Parameters:
    //   converter:
    //     The FileHelpers.ConverterKind used for the transformations.
    //
    //   arg1:
    //     The first param passed directly to the Converter Constructor.
    //
    //   arg2:
    //     The second param passed directly to the Converter Constructor.
    //
    //   arg3:
    //     The third param passed directly to the Converter Constructor.
    public FieldConverterAttribute(ConverterKind converter, string arg1, string arg2, string arg3);
    //
    // Summary:
    //     Indicates a custom FileHelpers.ConverterBase implementation.
    //
    // Parameters:
    //   customConverter:
    //     The Type of your custom converter.
    //
    //   arg1:
    //     The first param passed directly to the Converter Constructor.
    //
    //   arg2:
    //     The second param passed directly to the Converter Constructor.
    //
    //   arg3:
    //     The third param passed directly to the Converter Constructor.
    public FieldConverterAttribute(Type customConverter, string arg1, string arg2, string arg3);
}

Answer 1

参数FieldConverterAttribute(ConverterKind, params string[])没有重载。

有一个 FieldConverterAttribute(ConverterKind, string, string, string)因此您最多可以提供3种格式。

如果您需要更多，那么您可以创建自己的转换器：

public class CustomDateTimeConverter : ConverterBase
{
    public CustomDateTimeConverter(string format1, string format2, string format3, string format4)
    {
        _FormatStrings = new string[] { format1, format2, format3, format4} ;
    }

    private string[] _FormatStrings;

    public override object StringToField(string from)
    {
        foreach (string formatString in _FormatStrings)
        {
            DateTime dt;
            if (DateTime.TryParseExact(from, formatString, CultureInfo.InvariantCulture, DateTimeStyles.None, out dt))
                return dt;
        }
        throw new ConvertException(from, typeof(DateTime));
    }
}

然后你的领域看起来像

[FieldConverter(typeof(CustomDateTimeConverter), "MM/dd/yyyy", "MM/d/yyyy", "M/d/yyyy", "M/dd/yyyy")]
public DateTime Field1;

Answer 2

关于你的第一条评论，我不知道Filehelpers，但我使用过的每个图书馆都要求你指定你想要识别/解析的格式。 .Net的DateTime工具也不例外。但是，.Net确实提供了一个有用的函数，可以返回所有内置格式，然后可以使用TryParse()（documentation）进行迭代。

例如，以下代码使用内置DateTimeFormatInfo.GetAllDateTimeFormats()（documentation here）来循环128个自定义日期时间格式。（此代码演示了“往返”：将日期转换为字符串然后解析字符串）：

using System;
using System.Globalization;
public class Example
{
      public static void Main()
   {
      DateTimeFormatInfo myDTFI = new CultureInfo("en-US", false).DateTimeFormat;

      char[] formats = { 'd', 'D', 'f', 'F', 'g', 'G', 'm', 'o', 
                           'r', 's', 't', 'T', 'u', 'U', 'y' };
      DateTime date1 = new DateTime(2011, 02, 01, 7, 30, 45, 0);
      DateTime date2;

      foreach (var fmt in formats) 
      {
         foreach (var pattern in myDTFI.GetAllDateTimePatterns(fmt))
         {
            // "round-trip" = convert the date to string, then parse it
            if (DateTime.TryParse(date1.ToString(pattern), out date2))
            {
                Console.WriteLine("{0:" + pattern + "} (format '{1}')",
                                  date1, pattern);
            }
         }
      }
   }
}

FileHelpers中的多个日期如何？

2 个答案: