CSV Helper Multiple Same column Names

Question

I have CSV file that has multiples columns with the same header name. I am using CsvHelper library. I want to collect their row values into one List but I am collecting first row value as many times I have header specified and not collecting from another index position. ex. COLUMN COLUMN Test1 Test2 Test3 Test4 I expect that my list has two elements first with value Test1,Test2 and second one with values Test3,Test4 but I first row has values Test1,Test1 and second Test3,Test3.

This is the mapping for this column

Map(m => m.COLUMN).ConvertUsing(row =>
                (row as CsvReader)?.FieldHeaders
                     .Where(header => header.StartsWith("COLUMN"))
                     .Select(header => row.GetField<string>(header))
                     .Where(value => !string.IsNullOrWhiteSpace(value))
                     .ToList()
            );

Can this be done with mapping? If I change Column names to COLUMN1 and COLUMN2 this works but that is not the solution for my problem.

Test1 and Test2 values are in the first row and Test3 and Test4 are in the second — user3690217

Josh Close Josh Close · Accepted Answer · 2017-10-04T21:06:07

There are many ways to do this. Here is one example.

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,List,List,List");
        writer.WriteLine("1,one,a,b,c");
        writer.WriteLine("1,two,d,e,f");
        writer.Flush();
        stream.Position = 0;

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

public class Test
{
    public int Id { get; set; }
    public string Name { get; set; }
    public List<string> List { get; set; }
}

public sealed class TestMap : CsvClassMap<Test>
{
    public TestMap()
    {
        Map(m => m.Id);
        Map(m => m.Name);
        Map(m => m.List).ConvertUsing(row =>
        {
            var list = new List<string>();
            list.Add(row.GetField("List", 0));
            list.Add(row.GetField("List", 1));
            list.Add(row.GetField("List", 2));
            return list;
        });
    }
}

Also, version 3 has mapping to enumerables built in.

Map(m => m.List).Name("List");

CSV Helper Multiple Same column Names

1 Answers