CsvHelper 从字符串中解析布尔值

Question

我目前正在尝试从 csv 文件中解析一个布尔值。我们注意到该值将成功解析

Yes

和

Y

（在任何情况下），但不会解析

No

和

N

我正在像这样映射类映射中的值：

Map(m => m.Enabled).Name("Enabled").TypeConverterOption(false, string.Empty);

是否有原因导致它会读为

Yes

而不是

No

？有没有办法添加解析

no

的能力？

Answer 1

在 4.0.3 版本中，此功能有效。

void Main()
{
    using (var stream = new MemoryStream())
    using (var writer = new StreamWriter(stream))
    using (var reader = new StreamReader(stream))
    using (var csv = new CsvReader(reader))
    {
        writer.WriteLine("Id,Name,IsSomething");
        writer.WriteLine("1,one,Yes");
        writer.WriteLine("2,two,Y");
        writer.WriteLine("3,three,No");
        writer.WriteLine("4,four,N");
        writer.Flush();
        stream.Position = 0;

        csv.Configuration.RegisterClassMap<TestMap>();
        csv.GetRecords<Test>().ToList().Dump();
    }
}

public class Test
{
    public int Id { get; set; }
    public string Name { get; set; }
    public bool IsSomething { get; set; }
}

public sealed class TestMap : ClassMap<Test>
{
    public TestMap()
    {
        Map(m => m.Id);
        Map(m => m.Name);
        Map(m => m.IsSomething)
            .TypeConverterOption.BooleanValues(true, true, "Yes", "Y")
            .TypeConverterOption.BooleanValues(false, true, "No", "N");
    }
}

在 2.16.3 版本中，此功能有效。

void Main()
{
    using (var stream = new MemoryStream())
    using (var writer = new StreamWriter(stream))
    using (var reader = new StreamReader(stream))
    using (var csv = new CsvReader(reader))
    {
        writer.WriteLine("Id,Name,IsSomething");
        writer.WriteLine("1,one,Yes");
        writer.WriteLine("2,two,Y");
        writer.WriteLine("3,three,No");
        writer.WriteLine("4,four,N");
        writer.Flush();
        stream.Position = 0;

        csv.Configuration.RegisterClassMap<TestMap>();
        csv.GetRecords<Test>().ToList().Dump();
    }
}

public class Test
{
    public int Id { get; set; }
    public string Name { get; set; }
    public bool IsSomething { get; set; }
}

public sealed class TestMap : CsvClassMap<Test>
{
    public TestMap()
    {
        Map(m => m.Id);
        Map(m => m.Name);
        Map(m => m.IsSomething)
            .TypeConverterOption(true, "Yes", "Y")
            .TypeConverterOption(false, "No", "N");
    }
}

Answer 2

作为扩展方法，让使用更简单。

Map(x => x.IsActive).Name("Active").WithExtendedBooleanValues();

在 v15 上进行了测试，但我确信在此之前它可以正常工作。

namespace CsvHelper.Configuration
{
    public static class MemberMapExtensions
    {
        /// <summary>
        /// Adds "y", "yes" and "set to yes" and the "no" equivalents to the list of accepted boolean values
        /// for this member map.
        /// </summary>
        public static MemberMap<TClass, TMember> WithExtendedBooleanValues<TClass, TMember>(
            this MemberMap<TClass, TMember> memberMap)
        {
            memberMap
                // Note: It's case insensitive
                // https://github.com/JoshClose/CsvHelper/blob/master/src/CsvHelper/TypeConversion/BooleanConverter.cs
                .TypeConverterOption.BooleanValues(true, clearValues: false, "y", "yes", "set to yes")
                .TypeConverterOption.BooleanValues(false, clearValues: false, "n", "no", "set to no");

            return memberMap;
        }
    }
}

Answer 3

我们在版本 7 中使用以下内容

单个映射的用法：

Map(m => m.IsSomething).Name("IsSomething").TypeConverter<MyBooleanConverter>();

申请CSV阅读器的用途

csv.Configuration.TypeConverterCache.AddConverter<bool>(new MyBooleanConverter());

代码：

public sealed class MyBooleanConverter : DefaultTypeConverter
{
    public override object ConvertFromString(string text, IReaderRow row, MemberMapData memberMapData)
    {
        if(TryParseConvertBoolean(text, out bool result))
        {
            return result;
        }

        return null;
    }

    public static bool TryParseConvertBoolean(string value, out bool result)
    {
        result = false;
        try
        {
            if (string.IsNullOrWhiteSpace(value))
                return false;
            else
            {
                var lower = value.ToLower();

                if (lower == "no" || lower == "n")
                {
                    result = false;
                    return true;
                }
                else if (lower == "yes" || lower == "y")
                {
                    result = true;
                    return true;
                }
            }
        }
        catch { }

        return false;
    }
}

Answer 4

上面的答案有一个错误，这是我正在使用的简化版本，效果很好：

public sealed class MyBooleanConverter : DefaultTypeConverter
{
    public override object ConvertFromString(string text, IReaderRow row, MemberMapData memberMapData)
    {
        if (string.IsNullOrWhiteSpace(text)) return false;
        var lower = text.ToLower();
        if (lower == "yes" || lower == "y" || lower == "1") return true;
        return false;
    }
}