CsvHelper Format Decimal using ClassMap

Question

I have column columns in the file that will have values like "000120000" that needs to be converted into "1200.00" using CsvHelper ClassMap. I am currently using Decimal type for those columns and have the NumberStyle in the ClassMap that is truncating the zero's at the beginning. So i am getting the value as "120000". I tried using the "TypeConverterOption.Format("0.00")" but no luck. So would like to know if there is a way i can convert the value "120000" to "1200.00" using ClassMap. I can even divide by 100 but don't want to do this everywhere i use the field so need to do this logic in the ClassMap. Thank you in advance for helping me out on this.

In the ClassMap I have the below code: csvConfig.TypeConverterOptionsCache.GetOptions<decimal?>().NumberStyle = NumberStyles.Number | NumberStyles.AllowDecimalPoint | NumberStyles.AllowExponent;

Ex: "000120000" -> "1200.00" (right now i am getting the value as "120000")

Answer 1

This is one way you could do it. With a custom converter.

public class Program
{
    static void Main(string[] args)
    {
        using (var stream = new MemoryStream())
        using (var writer = new StreamWriter(stream))
        using (var reader = new StreamReader(stream))
        using (var csv = new CsvReader(reader, CultureInfo.InvariantCulture))
        {
            writer.WriteLine("Id,MoveDecimalPoint,NoMoveDecimalPoint");
            writer.WriteLine("1,000120000,000120000");
            writer.Flush();
            stream.Position = 0;

            csv.Configuration.RegisterClassMap<FooClassMap>();

            var records = csv.GetRecords<Foo>().ToList();
        }
    }
}

public class Foo
{
    public int Id { get; set; }
    public decimal MoveDecimalPoint { get; set; }
    public decimal NoMoveDecimalPoint { get; set; }
}

public class FooClassMap : ClassMap<Foo>
{
    public FooClassMap()
    {
        AutoMap(CultureInfo.InvariantCulture);
        Map(m => m.MoveDecimalPoint).TypeConverter<MoveDecimalConverter>();
    }
}

public class MoveDecimalConverter : DecimalConverter
{
    public override object ConvertFromString(string text, IReaderRow row, MemberMapData memberMapData)
    {
        var numberStyle = memberMapData.TypeConverterOptions.NumberStyle ?? NumberStyles.Number;

        if (decimal.TryParse(text, numberStyle, memberMapData.TypeConverterOptions.CultureInfo, out var d))
        {
            return d / 100;
        }

        return base.ConvertFromString(text, row, memberMapData);
    }
}

If you wanted to have ALL decimal values move two decimal places, you could add the MoveDecimalConverter to the configuration.

public class Program
{
    static void Main(string[] args)
    {
        using (var stream = new MemoryStream())
        using (var writer = new StreamWriter(stream))
        using (var reader = new StreamReader(stream))
        using (var csv = new CsvReader(reader, CultureInfo.InvariantCulture))
        {
            writer.WriteLine("Id,MoveDecimalPoint,NoMoveDecimalPoint");
            writer.WriteLine("1,000120000,000120000");
            writer.Flush();
            stream.Position = 0;

            csv.Configuration.TypeConverterCache.AddConverter<decimal>(new MoveDecimalConverter());

            var records = csv.GetRecords<Foo>().ToList();
        }
    }
}

You could also use ConvertUsing()

public class Program
{
    static void Main(string[] args)
    {
        using (var stream = new MemoryStream())
        using (var writer = new StreamWriter(stream))
        using (var reader = new StreamReader(stream))
        using (var csv = new CsvReader(reader, CultureInfo.InvariantCulture))
        {
            writer.WriteLine("Id,MoveDecimalPoint,NoMoveDecimalPoint");
            writer.WriteLine("1,000120000,000120000");
            writer.Flush();
            stream.Position = 0;

            csv.Configuration.RegisterClassMap<FooClassMap>();

            var records = csv.GetRecords<Foo>().ToList();
        }
    }
}

public class Foo
{
    public int Id { get; set; }
    public decimal MoveDecimalPoint { get; set; }
    public decimal NoMoveDecimalPoint { get; set; }
}

public class FooClassMap : ClassMap<Foo>
{
    public FooClassMap()
    {
        AutoMap(CultureInfo.InvariantCulture);
        Map(m => m.MoveDecimalPoint).ConvertUsing(row =>
        {
            if (decimal.TryParse(row["MoveDecimalPoint"], NumberStyles.Number, row.Configuration.CultureInfo, out var d))
            {
                return d / 100;
            } 
            else
            {
                return 0;
            }
        });
    }
}