read from csv to object[] C#

Question

I am trying to read from a .csv file to an object array.

There are other solutions here that give solutions for lists but I cannot seem to make it work for me.

Object definition:

public class DTOClass
{
    //declare data members
    [DataMember]
    public DateTime Date { get; set; }
    [DataMember]
    public string stock_symbol { get; set; }
    [DataMember]
    public double stock_price_open { get; set; }
    [DataMember]
    public double stock_price_close { get; set; }
    [DataMember]
    public double stock_price_low { get; set; }
    [DataMember]
    public double stock_price_high { get; set; }
    [DataMember]
    public double stock_price_adj_close { get; set; }
    [DataMember]
    public long stock_volume { get; set; }
    [DataMember]
    public string stock_exchange { get; set; }
}

Instance declaration:

private DTOClass[] _dTOs;

Filter method:

private List<DTOClass> FromCsv(string csvLine, List<DTOClass> rest)
{
    DataTable _dt = new DataTable();

    string[] values = csvLine.Split(',');

    int j = _dt.Rows.Count;
    for (int i = 0; i < j; i++)
    {
        DTOClass dto = new DTOClass();

        dto.Date = Convert.ToDateTime(values[0]);
        dto.stock_symbol = Convert.ToString(values[1]);
        dto.stock_price_open = Convert.ToDouble(values[2]);
        dto.stock_price_close = Convert.ToDouble(values[3]);
        dto.stock_price_low = Convert.ToDouble(values[4]);
        dto.stock_price_high = Convert.ToDouble(values[5]);
        dto.stock_price_adj_close = Convert.ToDouble(values[6]);
        dto.stock_volume = Convert.ToInt64(values[7]);
        dto.stock_exchange = Convert.ToString(values[8]);

        rest.Add(dto);
    }

    return rest;
}

Calling filter:

DTO = File.OpenText(Filename).ReadLine().Select(v => FromCsv(v.ToString(), 
_restDto)).ToArray();

I need this to return to an object array because it then goes into a CollectionView on a datagrid.

But I keep getting this error:

"Cannot implicitly convert type 'System.Collections.Generic.List[]' to 'MBM.Services.DTOClass[]'"

I know that I'm obviously returning a list of a list, but I've tried other methods that are offered and I'm simply stumped.

I've also tried this:

private static DataTable GetDataTableFromCSVFile(string csv_file_path)
{
    DataTable csvData = new DataTable();

    try
    {
        using (TextFieldParser csvReader = new TextFieldParser(csv_file_path))
        {
            csvReader.SetDelimiters(new string[] { "," });
            //csvReader.HasFieldsEnclosedInQuotes = true;
            string[] colFields = csvReader.ReadFields();

            foreach (string column in colFields)
            {
                DataColumn datecolumn = new DataColumn(column);
                datecolumn.AllowDBNull = true;
                csvData.Columns.Add(datecolumn);
            }

            while (!csvReader.EndOfData)
            {
                string[] fieldData = csvReader.ReadFields();
                //Making empty value as null
                for (int i = 0; i < fieldData.Length; i++)
                {
                    if (fieldData[i] == "")
                    {
                        fieldData[i] = null;
                    }
                }

                csvData.Rows.Add(fieldData);
            }
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }

    return csvData;
}

Calling with:

DataTable csvData = GetDataTableFromCSVFile(Filename);

But this doesn't seem to return anything from the file.

Any help is appreciated, thanks.

Answer 1

There's no point in recreating the wheel, Id just use CsvHelper, it has support for what you're doing in addition to handling malformed CSV's you can additionally set up mapping like so:

public sealed class MyClassMap : ClassMap<MyClass>
{
    public MyClassMap()
    {
        AutoMap();
        Map( m => m.CreatedDate ).Ignore();
    }
}

Then you can get the object like so:

var csv = new CsvReader( textReader );
var records = csv.GetRecords<MyClass>();

Answer 2

One simple way will be to split the lines and select them into your new object.

var result = File.ReadAllLines("pathTo.csv")
                .Select(line => line.Split(','))
                .Select(x => new MyObject { 
                    prop1 = x[0],
                    prop2 = x[1],
                    //etc.. 
                })
                .ToArray();