ReadFields() in TextFieldParser throwing exception

Question

I have a bunch of csv files in a folder. Here is a sample:

Item    Value
Row1    Val1
Row2    Val2
Row3    Val3
Row4    Val4"
Row5    Val5

I had written a code to plot a chart based on the information available in all the csv file in that folder. Here is my button click event:

Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles generatePlot.Click

        Dim dirs As FileInfo() = GetFilesInDirectory("*.csv", True) 'Get all the csv file from result folder in descending order (creation date)
        Dim diNext As FileInfo

        Try
            For Each diNext In dirs.Reverse
                Using MyReader As New FileIO.TextFieldParser(diNext.FullName)
                    MyReader.TextFieldType = FileIO.FieldType.Delimited
                    MyReader.SetDelimiters(",")
                    Dim currentRow As String()
                    While Not MyReader.EndOfData
                        currentRow = MyReader.ReadFields()
                        processRow(diNext, currentRow)
                    End While
                End Using
            Next
        Catch ex As Exception
            MessageBox.Show(ErrorToString)
        End Try

        'Save chart as an image
        Chart1.SaveImage(imageSave, System.Drawing.Imaging.ImageFormat.Bmp)

    End Sub

If you look at my sample csv, Row4 has a value of Val4". Note the double quote in it. And, I am getting an exception in my code at currentRow = MyReader.ReadFields() which says Line 5 cannot be parsed using the current delimiter. I know that the reason is because of the presence of double quote. Since this is a string array, I thought that I need to create a function to process each item in the array and trim out the double quote. But, I can't do it as the exception is thrown even before I can process the string array.

Any idea on how to solve this?

Hari

Answer 1

A StreamReader can be used to read text files, just look at the example below to achieve your needs:

Note that the MemoryStream and the Writer are not needed for you, just the Reader.

Public Sub ReadTest()
    Using MemoryStream As New IO.MemoryStream()
        Dim Writer As New IO.StreamWriter(MemoryStream) 'Writing on a memory stream to emulate a File
        Writer.WriteLine("Item,Value")
        Writer.WriteLine("Row1,Val1")
        Writer.WriteLine("Row2,Val2")
        Writer.WriteLine("Row3,Val3")
        Writer.WriteLine("Row4,Val4""")
        Writer.WriteLine("Row5,Val5")

        Writer.Flush()
        MemoryStream.Position = 0 'Reseting the MemoryStream to Begin Reading

        Dim Reader As New IO.StreamReader(MemoryStream) 'Reading from the Memory but can be changed into the File Path
        While Not Reader.EndOfStream
            Dim Line As String = Reader.ReadLine
            Dim Values() = Line.Split(",")
            'Values(0) will contain the First Item
            'Values(1) will contain the second Item

            Values(1).Replace("""", "") 'Remove the quote from the value string

        End While

    End Using
End Sub