使用CsvHelper写入CSV文件时的自定义转换 [英] Custom conversions when writing CSV files using CsvHelper

问题描述

最近我一直在做一些CSV读写操作，遇到了 CsvHelper 至今。我遇到了一个小问题；我在读取文件时使用自定义转换器，但是当我将它们写回时，该格式会丢失。我的CSV格式如下：

I've been doing some CSV reading and writing lately, and ran across CsvHelper which is fantastic so far. I've ran into one small problem; I use a custom converter when reading the files, but when I write them back out, that format is lost. My CSV format looks like this:

67,1234-1,20150115,750,20150115,1340,549,549,406,0,FRG

20150115,750 字段映射到称为开始的单个 DateTime 字段（因此，2015年1月15日上午7:50）。我的类映射如下所示：

The fields 20150115,750 map to a single DateTime field called Start (So, 01/15/2015 7:50 AM). My class map looks like this:

public sealed class DutyMap : CsvClassMap<Duty>
{
    static readonly CultureInfo enUS = new CultureInfo("en-US");

    public DutyMap()
    {
        Map(m => m.PersonId).Index(0);
        Map(m => m.DutyName).Index(1);
        Map(m => m.Start).ConvertUsing(row => ParseDate(row.GetField<String>(2), row.GetField<String>(3)));
        Map(m => m.End).ConvertUsing(row => ParseDate(row.GetField<String>(4), row.GetField<String>(5)));
        Map(m => m.DutyTime1).Index(6);
        Map(m => m.DutyTime2).Index(7);
        Map(m => m.FlightTime).Index(8);
        Map(m => m.CreditHours).Index(9);
        Map(m => m.DutyType).Index(10);
    }

    private static DateTime ParseDate(string date, string time)
    {
        DateTime ret;

        if (time.Length < 4)
            time = new String('0', 4 - time.Length) + time;

        if (!DateTime.TryParseExact(date + time, "yyyyMMddHHmm", enUS, DateTimeStyles.None, out ret))
            throw new FormatException(String.Format("Could not parse DateTime.  Date: {0} Time: {1}", date, time));

        return ret;
    }
}

这很好用，现在我可以调用par整个文件如下所示：

This works great, and I can now call parse an entire file like so:

var csv = new CsvReader(sr);
csv.Configuration.HasHeaderRecord = false;
csv.Configuration.RegisterClassMap<DutyMap>();

Data = csv.GetRecords<Duty>().ToList();

但是，当我写入文件时：

csv.WriteRecords(Data);

文件的写法如下：

67,7454-1,1/15/2015 7:50:00 AM,1/15/2015 1:40:00 PM,549,549,406,0,FPG

在文档中，我看不到在编写时指定对话功能的方法>，仅阅读。到目前为止，我发现的唯一解决方案是手动手动写入每条记录：

Looking through the documentation, I don't see a way to specify a conversation function upon writing, only reading. The only solution I've found so far is to manually write each record by hand:

var csv = new CsvWriter(sw);
foreach (var item in Data)
{
    csv.WriteField(item.PersonId);
    csv.WriteField(item.DutyName);
    csv.WriteField(item.Start.ToString("yyyyMMdd"));
    csv.WriteField(item.Start.ToString("Hmm"));
    csv.WriteField(item.End.ToString("yyyyMMdd"));
    csv.WriteField(item.End.ToString("Hmm"));
    csv.WriteField(item.DutyTime1);
    csv.WriteField(item.DutyTime2);
    csv.WriteField(item.FlightTime);
    csv.WriteField(item.CreditHours);
    csv.WriteField(item.DutyType);

    csv.NextRecord();
}

是否有更好的方法？谢谢！

Is there a better way to do this? Thanks!

推荐答案

您可以使用自定义类型转换器（ https://github.com/JoshClose/CsvHelper/wiki/Custom-TypeConverter ）。只需重写 ConvertToString 方法。

You can do it with a custom type converters (https://github.com/JoshClose/CsvHelper/wiki/Custom-TypeConverter). Just override ConvertToString method.

public class TestConverter : DefaultTypeConverter
{
    public override string ConvertToString(TypeConverterOptions options, object value)
    {
        return base.ConvertToString(options, value);
    }
}

并在映射时指定转换器：

and specify converter when mapping:

Map(m => m.PersonId).Index(0).TypeConverter<TestConverter>();

这篇关于使用CsvHelper写入CSV文件时的自定义转换的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！