I have a bunch of CSV files that I need to read that are similar except for the addition of a column. Essentially, the old CSV format has 7 columns, and the new will have 8. No headers. Once read, the new column will be defaulted/edited and then the file will have 8 columns when written out - so future reads will now have the new column.
So I'm trying to do something like this CvsHelper example: Reading Multiple Record Types
except the only difference is in the number of columns in the file - not an identifying field value.
I tried a CsvParser in its own using() with a single Read() of the first line of the file to ascertain the column count with the idea that a CsvReader in a subsequent using() could register a count specific ClassMap for the CsvReader.GetRecords. However there doesn't seem to be a property or method that answers the number of columns that the parser has encountered. Same with the CsvReader.Read() - the CsvReader.Context.ColumnCount is zero after the Read(). Any ideas / pointers appreciated.
Update
Here's my revised code (long names, I know) - thanks for the suggestion David:
namespace TopazDomain.Classes
{
public class FootprintComponentMap : Entity<int>
{
private const int footprintWidth = 40;
[StringLength(footprintWidth)]
public string Footprint { get; set; }
private const int valueWidth = 40;
[StringLength(valueWidth)]
public string Value { get; set; }
public int Component { get; set; }
public int Head { get; set; }
private const int rotationWidth = 9;
[StringLength(rotationWidth)]
public string CompR { get; set; }
private const int polarizedWidth = 2;
[StringLength(polarizedWidth)]
public string Polarized { get; set; }
private const int commentWidth = 40;
public string Comment { get; set; }
[StringLength(rotationWidth)]
public string LibR { get; set; }
// navigation
[Required]
public FootprintComponentMapFile FootprintComponentMapFile { get; set; }
public FootprintComponentMap()
{
Footprint = String.Empty;
Value = String.Empty;
Component = 0;
Head = 0;
CompR = "0.00";
Polarized = "N";
Comment = String.Empty;
LibR = "0.00";
}
public FootprintComponentMap(FootprintComponentMap footprintComponentMap) : this()
{
Footprint = footprintComponentMap.Footprint;
Value = footprintComponentMap.Value;
Component = footprintComponentMap.Component;
Head = footprintComponentMap.Head;
CompR = footprintComponentMap.CompR;
Polarized = footprintComponentMap.Polarized;
Comment = footprintComponentMap.Comment;
LibR = footprintComponentMap.LibR;
}
public FootprintComponentMap(string footprint, string value, int componentNumber, int headNumber, string componentR,
string polarized, string libraryR, string comment) : this()
{
Footprint = footprint;
Value = value;
Component = componentNumber;
Head = headNumber;
CompR = componentR;
Polarized = polarized;
Comment = comment;
LibR = libraryR;
}
}
}
namespace TopazDomain.Classes.Extensions
{
public static class FootprintComponentMapFileExtensions
{
public sealed class FootprintComponentReadMapper : ClassMap<FootprintComponentMap>
{
public FootprintComponentReadMapper()
{
Map(m => m.Footprint).Index(0);
Map(m => m.Value).Index(1);
Map(m => m.Component).Index(2);
Map(m => m.Head).Index(3);
Map(m => m.CompR).Index(4);
Map(m => m.Polarized).Index(5);
Map(m => m.Comment).Index(6);
Map(m => m.LibR).ConvertUsing(row =>
{
if (row.TryGetField(7, out string field))
{
return field;
}
else
{
return String.Empty;
}
});
}
}
public sealed class FootprintComponentWriteMapper : ClassMap<FootprintComponentMap>
{
public FootprintComponentWriteMapper()
{
Map(m => m.Footprint).Index(0);
Map(m => m.Value).Index(1);
Map(m => m.Component).Index(2);
Map(m => m.Head).Index(3);
Map(m => m.CompR).Index(4);
Map(m => m.Polarized).Index(5);
Map(m => m.Comment).Index(6);
Map(m => m.LibR).Index(7);
}
}
public static bool ImportFootprintComponentMaps(this FootprintComponentMapFile footprintComponentMapFile,
string filename)
{
bool done = false;
using (var lineReader = new LineReader(filename))
using (var csv = new CsvReader(lineReader, CultureInfo.InvariantCulture))
{
csv.Configuration.RegisterClassMap<FootprintComponentReadMapper>();
footprintComponentMapFile.FootprintComponentMaps = csv.GetRecords<FootprintComponentMap>().ToList();
done = true;
}
return done;
}
public static bool ExportFootprintComponentMaps(this FootprintComponentMapFile footprintComponentMapFile,
string filename)
{
bool done = false;
CsvConfiguration cvsConfiguration = new CsvConfiguration(CultureInfo.InvariantCulture);
cvsConfiguration.HasHeaderRecord = false;
using (var lineWriter = new StreamWriter(filename))
using (var csv = new CsvWriter(lineWriter, cvsConfiguration))
{
csv.Configuration.RegisterClassMap<FootprintComponentWriteMapper>();
csv.WriteRecords(footprintComponentMapFile.FootprintComponentMaps);
done = true;
}
return done;
}
}
}
You could have a new object with the 8 properties and map the 8th column conditionally with ConvertUsing.
public class OldFoo
{
public int Id { get; set; }
public string FirstName { get; set; }
}
public class NewFoo
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
public class NewFooClassMap : ClassMap<NewFoo>
{
public NewFooClassMap()
{
Map(m => m.Id).Index(0);
Map(m => m.FirstName).Index(1);
Map(m => m.LastName).ConvertUsing(row => {
if(row.TryGetField(2, out string field))
{
return field;
}
else
{
return null;
}
});
}
}
public class Program
{
public static void Main(string[] args)
{
using (MemoryStream stream = new MemoryStream())
using (StreamWriter writer = new StreamWriter(stream))
using (StreamReader reader = new StreamReader(stream))
using (CsvReader csv = new CsvReader(reader, CultureInfo.InvariantCulture))
{
writer.WriteLine("1,Bob");
writer.WriteLine("2,Davey");
writer.Flush();
stream.Position = 0;
csv.Configuration.RegisterClassMap<NewFooClassMap>();
csv.Configuration.HasHeaderRecord = false;
var records = csv.GetRecords<NewFoo>().ToList();
}
using (MemoryStream stream = new MemoryStream())
using (StreamWriter writer = new StreamWriter(stream))
using (StreamReader reader = new StreamReader(stream))
using (CsvReader csv = new CsvReader(reader, CultureInfo.InvariantCulture))
{
writer.WriteLine("1,Bob,Barker");
writer.WriteLine("2,Davey,Jones");
writer.Flush();
stream.Position = 0;
csv.Configuration.RegisterClassMap<NewFooClassMap>();
csv.Configuration.HasHeaderRecord = false;
var records = csv.GetRecords<NewFoo>().ToList();
}
}
}