Converting a List to a string

Question

I need to convert a few rows of data I am pulling from a DataTable from a List into a string separated by commas. Here is what I have now. It does not work at all (it shows System.Data.DataRow,System.Data.DataRow in the messagebox), however a breakpoint at list shows the correct number of rows, with the correct data.

cmd3.Fill(badnum);

List<DataRow> list = badnum.AsEnumerable().ToList();
string badnumbers = string.Join(",", list);
MessageBox.Show(badnumbers);

Or rather, define the input `List` and the expected resulting string. How should a single `DataRow` be represented as a string? — stakx - no longer contributing, Jul 30 '13 at 19:01

score 3 · Accepted Answer · answered Jul 30 '13 at 18:48

3

Your issue lies in how you're using DataRow.
DataRows contain multiple values.

The typical use is referencing a particular column within the row.

E.g. dataRow["MyColumnName"] or by index dataRow[0]

answered Jul 30 '13 at 18:48

Khan

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score 1 · Answer 2 · answered Jul 30 '13 at 18:49

1

string.Join() needs a string[] or an IEnumerable<string>

Try this:

List<DataRow> list = badnum.AsEnumerable().ToList();
string badnumbers = string.Join(",", list.Select(r=>r["MyColumn"].ToString()).ToArray());
MessageBox.Show(badnumbers);

answered Jul 30 '13 at 18:49

Agustin Meriles

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Really? http://msdn.microsoft.com/en-us/library/dd992421.aspx – Dennis Jul 30 '13 at 18:54
If you are using .Net 4.0 + you could use IEnumerable, but lower versions needs string[] – Agustin Meriles Jul 30 '13 at 19:29
Is there something about .NET version in the question? – Dennis Jul 30 '13 at 19:33

score 0 · Answer 3 · answered Jul 30 '13 at 18:47

0

You don't need to convert to list. You can convert each row to csv as follows

    foreach (DataRow dr in badnum.Rows)
        string csv = String.Join(",", row.ItemArray);

answered Jul 30 '13 at 18:47

Ehsan

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score 0 · Answer 4 · answered Jul 30 '13 at 19:15

Something like this ought to do you:

static void Main( string[] args )
{
  const string connectString = "Server=localhost;Database=sandbox;Trusted_Connection=True;";

  DataTable dt = new DataTable() ;
  using ( SqlConnection conn = new SqlConnection(connectString) )
  using ( SqlCommand cmd = conn.CreateCommand() )
  using ( SqlDataAdapter sda = new SqlDataAdapter(cmd) )
  {
    cmd.CommandText = @"select * from sys.objects" ;
    cmd.CommandType = CommandType.Text; 
    conn.Open();
    int rows = sda.Fill(dt) ;
  }

  Func<string,string> qt = x => "\"" + x.Replace("\"","\"\"") + "\"" ;

  DataRow dr = dt.Rows[0] ;
  string csv = dt.Columns
                 .Cast<DataColumn>()
                 .Select( c => qt(c.ColumnName) + "=" + qt(dr[c].ToString()) )
                 .Aggregate( (acc,s) => acc + "," + s )
                 ;
  Console.WriteLine(csv) ;

  return ;
}

Define your own semantics for what the row should look like.

Converting a List to a string

4 Answers4