Read only particular fields from CSV File in vb.net
I have this code to read a CVS file. It reads each line, devides each line by delimiter ',' and stored the field values in array 'strline()' .
How do I extract only required fields from the CSV file?
For example if I have a CSV File like
Type,Group,No,Sequence No,开发者_JS百科Row No,Date (newline) 0,Admin,3,345678,1,26052010 (newline) 1,Staff,5,78654,3,26052010
I Need only the value of columns Group,Sequence No and date.
Thanks in advance for any ideas.
Dim myStream As StreamReader = Nothing
' Hold the Parsed Data
Dim strlines() As String
Dim strline() As String
Try
myStream = File.OpenText(OpenFile.FileName)
If (myStream IsNot Nothing) Then
' Hold the amount of lines already read in a 'counter-variable'
Dim placeholder As Integer = 0
strlines = myStream.ReadToEnd().Split(Environment.NewLine)
Do While strlines.Length <> -1 ' Is -1 when no data exists on the next line of the CSV file
strline = strlines(placeholder).Split(",")
placeholder += 1
Loop
End If
Catch ex As Exception
LogErrorException(ex)
Finally
If (myStream IsNot Nothing) Then
myStream.Close()
End If
End Try
1) DO NOT USE String.Split
!!
CSV data can contain comma's, e.g.
id,name
1,foo
2,"hans, bar"
Also as above you would need to handle quoted fields etc... See CSV Info for more details.
2) Check out TextFieldParser - it hadles all this sort of thing.
It will handle the myriad of different escapes you can't do with string.split...
Sample from: http://msdn.microsoft.com/en-us/library/cakac7e6.aspx
Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser("C:\TestFolder\test.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
The MyReader.ReadFields()
part will get you an array of strings, from there you'll need to use the index etc...
PK :-)
Maybe instead of only importing selected fields, you should import everything, then only use the ones you need.
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