c# reading csv file gives not a valid path

Question

I can't seem to read a .csv file using the following connection string:

var fileName = string.Format("{0}{1}", AppDomain.CurrentDomain.BaseDirectory, "Uploads\\countrylist.csv");
string connectionString = string.Format(@"Provider=Microsoft.Jet.OLEDB.4.0; Data Source={0}; Extended Properties=""text;HDR=YES;FMT=Delimited""", fileName);
OleDbConnection oledbConn = new OleDbConnection(connectionString);
oledbConn.Open();

It gives the following error:

'D:\arrgh\arrgh\Uploads\countrylist.csv' is not a valid path. Make sure that the path name is spelled correctly and that you are connected to the server on which the file resides.

I verified that the file is there. What is happening here?

Answer 1

Ok, I dug a little further and it seems that my connection string is wrong. With CSV files, you don't specify the actual file name but the directory where it belongs, eg.

var fileName = string.Format("{0}{1}", AppDomain.CurrentDomain.BaseDirectory, "Uploads\\");
string connectionString = string.Format(@"Provider=Microsoft.Jet.OLEDB.4.0; Data Source={0}; Extended Properties=""text;HDR=YES;FMT=Delimited""", fileName);
OleDbConnection oledbConn = new OleDbConnection(connectionString);
oledbConn.Open();
var cmd = new OleDbCommand("SELECT * FROM [countrylist.csv]", oledbConn);

And you specify the filename in the SelectCommand. What a strange way of doing it. It's working for me now.

Answer 2

I recommend you use a CSV parser rather than using the OLEDB data provider.

Search and you'll find many (free) candidates. Here are a few that worked for me:

A portable and efficient generic parser for flat files (easiest to use, IMO)
A Fast CSV Reader (easy to use, great for large data sets)
FileHelpers library (flexible, includes code generators, bit of a learning curve)

Typically these will allow you to specify properties of your CSV (delimiter, header, text qualifier, etc.) and with a method call your CSV is dumped to a data structure of some sort, such as a DataTable or List<>.

If you'll be working at all with CSV, it's worth checking out a CSV parser.

Answer 3

The way to combine paths and filenames is to use:

fullFilename = System.IO.Path.Combine(folderfilepath, Filename);

in your example:

var fileName = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, @"Uploads\countrylist.csv");

Answer 4

If you're just trying to read a CSV file with C#, the easiest thing is to use the Microsoft.VisualBasic.FileIO.TextFieldParser class. It's actually built into the .NET Framework, instead of being a third-party extension.

Yes, it is in Microsoft.VisualBasic.dll, but that doesn't mean you can't use it from C# (or any other CLR language).

Here's an example of usage, taken from the MSDN documentation:

Using MyReader As New _
Microsoft.VisualBasic.FileIO.TextFieldParser("C:\testfile.txt")
   MyReader.TextFieldType = FileIO.FieldType.Delimited
   MyReader.SetDelimiters(",")
   Dim currentRow As String()
   While Not MyReader.EndOfData
      Try
         currentRow = MyReader.ReadFields()
         Dim currentField As String
         For Each currentField In currentRow
            MsgBox(currentField)
         Next
      Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
      MsgBox("Line " & ex.Message & _
      "is not valid and will be skipped.")
      End Try
   End While
End Using

Again, this example is in VB.NET, but it would be trivial to translate it to C#.

Answer 5

I had the same problem a few weeks ago trying to do some Office 2007 automation and spent too much time trying to fix it.

string connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileName + ";Extended Properties=\"Excel 12.0;HDR=YES;IMEX=1;\"";

Answer 6

If the D drive is a mapped network drive then you may need to use the UNC path:

\\computerName\shareName\path\

Answer 7

try this, A Fast CSV Reader, efficient CSV parser

CsvReader