Re: [2008] Editing CSV File
Re: [2008] Editing CSV File
Of course it's possible. A CSV file is just plain text. If you want more data then you simply open the file and write to it.
I believe that you already know how to use ADO.NET to read that file into a DataTable. You should start by doing that. You could then add a new DataColumn to the DataTable and set its Expression property to perfrom the calculation automatically for all rows. Given the nature of the calculation though, it might be easier to loop through the rows of the DataTable and calculate the value yourself, writing out the line to the file as you go.
vb.net Code:
Using writer As New StreamWriter("file path here")
For Each row As DataRow In table.Rows
'Perform the calculation and write out the row.
Next
End Using
Re: [2008] Editing CSV File
the code i am using to open the file is
Code:
Dim Filelocation As String
Dim Textfilestext As String
If OpenFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then
Filelocation = OpenFileDialog1.FileName
TextBox1.Text = Filelocation
Textfilestext = IO.File.ReadAllText(OpenFileDialog1.FileName)
Re: [2008] Editing CSV File
Weren't you using ADO.NET to read this CSV file in some other thread? Anyway, ReadAllText is the wrong way to read this file. It will just give you the whole file contents as a single string, which is useless. You need each individual field value so you'd have to break that string up into lines anyway, then each of those lines into fields. There's no point doing that when there's ways to read the file that will do that for you. As I said, ADO.NET can populate a DataTable for you. Alternatively you can use a TextFieldParser to read the file line by line, field by field.
Re: [2008] Editing CSV File
Quote:
Originally Posted by jmcilhinney
Weren't you using ADO.NET to read this CSV file in some other thread? Anyway, ReadAllText is the wrong way to read this file. It will just give you the whole file contents as a single string, which is useless. You need each individual field value so you'd have to break that string up into lines anyway, then each of those lines into fields. There's no point doing that when there's ways to read the file that will do that for you. As I said, ADO.NET can populate a DataTable for you. Alternatively you can use a TextFieldParser to read the file line by line, field by field.
Ok if i use this code ADO.Net
Code:
Private Function CsvToDataTable(ByVal filePath As String, ByVal hasHeaderLine As Boolean) As DataTable
Dim dt As DataTable = Nothing
Dim sourcePath As String = String.Empty
Dim csvFile As String = String.Empty
Dim conString As String = String.Empty
Dim conn As OleDb.OleDbConnection = Nothing
Dim adapter As OleDb.OleDbDataAdapter = Nothing
Dim selString As String = String.Empty
Dim header As String = "No"
Try
sourcePath = System.IO.Path.GetDirectoryName(filePath)
csvFile = System.IO.Path.GetFileName(filePath)
If hasHeaderLine Then header = "Yes"
conString = String.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=""text;HDR={1};FMT=Delimited"";", sourcePath, header)
conn = New OleDb.OleDbConnection(conString)
selString = "Select * From " & csvFile
adapter = New OleDb.OleDbDataAdapter(selString, conn)
dt = New DataTable(System.IO.Path.GetFileNameWithoutExtension(filePath))
conn.Open()
adapter.Fill(dt)
conn.Close()
Catch ex As Exception
MessageBox.Show(ex.Message)
Finally
adapter.Dispose()
conn.Dispose()
End Try
Return dt
End Function
how do i add a new column the code you gave me gives an error on streamwriter because i didnt dim in anywhere?
can u provide the exact code as i am new to this
Re: [2008] Editing CSV File
You don't "Dim" something. You "declare" it. "Dim" is one way to declare a variable. The Using statement is another, which I used in my code. The point of a Using block is to dispose the object you create at the end of the block. In this case that closes the file and releases the resource back to the OS.
If you create a DataTable, as you are with that ADO.NET code, then you can create a new DataColumn object and add it to the table's Columns collection. That said, there's no point doing so. You may as well just loop through the rows of the table, calculate the new value and then write out the line to the file. If you're not actually going to use the data in the DataTable for anything else then adding the new data to it doesn't server a purpose.
Re: [2008] Editing CSV File
Quote:
Originally Posted by jmcilhinney
If you create a DataTable, as you are with that ADO.NET code, then you can create a new DataColumn object and add it to the table's Columns collection. That said, there's no point doing so. You may as well just loop through the rows of the table, calculate the new value and then write out the line to the file. If you're not actually going to use the data in the DataTable for anything else then adding the new data to it doesn't server a purpose.
I want to use it for many purpses but the first thing i want to do is add a new column and do calculations in it
Quote:
You may as well just loop through the rows of the table, calculate the new value and then write out the line to the file.
If i knew how to do that i wouldnt be asking:(
Re: [2008] Editing CSV File
Quote:
Originally Posted by Orbit__
If i knew how to do that i wouldnt be asking:(
If I didn't know how to do it I would be reading the documentation for the DataColumn class and the DataTable.Columns property first. If I still couldn't work out how to do it, then I'd ask. I'd post what I had so far and ask if anyone could help me to change it to get it to work. Maybe it's just me but I always try first, then ask for help if I fail. Before you say it, I did the same when I was a beginner.
