CsvHelper Parsing boolean from String

Question

I'm currently trying to parse a value from a csv file that is a boolean. We've noticed that the value will successfully parse Yes and Y (in any case) but will not parse No and N

I'm mapping the value in the classmap like this:

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

Is there a reason why this would read Yes but not No and is there a way to add the ability to parse no?

So you say `false` should be converted from the empty string, right? Do you have any more configuration going on? — grek40, Oct 27 '17 at 09:02
https://stackoverflow.com/questions/2872710/can-net-convert-yes-no-to-boolean-without-if — Ansil F, Oct 27 '17 at 09:18

score 8 · Answer 1 · answered Oct 27 '17 at 20:21

In version 4.0.3, this works.

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");
    }
}

In version 2.16.3 this works.

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");
    }
}

In version 4.0.3 , I am wondering why we have to add two "true" instead of one. — Khant Htet Naing, Nov 19 '20 at 03:05

score 3 · Answer 2 · answered Nov 23 '21 at 15:05

As an extension method to make the usage a little easier.

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

Tested on v15, but I'm sure it works well before then.

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;
        }
    }
}

This is the ONLY working solution I've found anywhere. – unruledboy Apr 21 '22 at 23:32 — unruledboy, Apr 21 '22 at 23:32

Jon Edwards · Answer 3 · 2018-10-26T11:02:34.657

We use the following in version 7

Usage for an individual mapping:

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

Usage for applying to the CSV reader

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

Code:

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;
    }
}

CsvHelper Parsing boolean from String

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