Avatar of mehmast
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vb.net reading CSV file - null exception

Hello Experts
I am trying to parse CSV file which has 2 rows of data, its reading the first line correctly, storing in the structure variable but when I loop it through the second time, it errors when I try to read the first column (fields(0))

"Object reference not set to an instance of an object."

please can someone advice what is wrong with this code?

  Private Function ParseCSVs() As Boolean

        Dim LocalFilePath As String = String.Empty

        For Each aCSV As xCSV In _CSVs
            LocalFilePath = My.Settings.Item("GRFiles") & "DailyOrders\" & aCSV.CSVFileName
            Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser(LocalFilePath)

                MyReader.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited
                MyReader.Delimiters = New String() {","}  '{vbTab}
                Dim currentRow As String()
                'Loop through all of the fields in the file.  
                'If any lines are corrupt, report an error and continue parsing.  
                Dim OrderRequest As New cCSVOrderRequest
                OrderRequest.Items = New List(Of cCSVProductItem)

                Dim Product As ProductClass = Nothing
                Dim Item As cCSVProductItem = Nothing
                While Not MyReader.EndOfData

                        currentRow = MyReader.ReadFields()
                        ' Include code here to handle the row. 
                        Dim fields As String() = MyReader.ReadFields()
                        Item = New cCSVProductItem()
                        Item.OrderItemNumber = fields(0)
                        Item.PartNumber = fields(2)
                        Item.Description = fields(3)
                        Item.Quantity = fields(4)
                        Item.ShipTitle = fields(17)
                        Item.ShipToName = fields(18)
                        Item.ShipAddress1 = fields(19)
                        Item.ShipAddress2 = fields(20)
                        Item.ShipAddress3 = fields(21)
                        Item.ShipAddress4 = fields(22)
                        If fields(23).Contains("GB") Then
                            Item.ShipCountry = "238"
                            Item.ShipCountry = ""
                        End If
                        Item.ShipPostCode = fields(24)
                        Item.PhoneNumber = fields(28)
                    Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
                        Return False
                    End Try
                End While
                aCSV.OrderRequest = OrderRequest
            End Using
        Return True
    End Function

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Visual Basic.NET.NET Programming

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Last Comment
Fernando Soto

8/22/2022 - Mon
Fernando Soto

That is because you are reading both rows in the first pass and therefore when you try to get the next row there is no more data, fields(0) is null and you are trying to assign that to a variable in this line of code.

 Item.OrderItemNumber = fields(0)

This is where you are reading in both lines in the file in the first pass. Modify the code to read once per pass.

    '' First time you read the line from the file
    currentRow = MyReader.ReadFields()
    ' Include code here to handle the row. 
    '' Now you fread the second line in from the file 
    Dim fields As String() = MyReader.ReadFields()

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thank you for picking this up for me
i have headers in first row, so this line will ignore the headers
currentRow = MyReader.ReadFields()

the second and the third rows has data which I want to extract,

how can i make sure i only run the headers once in the loop? please advice
john hill

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thank you
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Fernando Soto

Not a problem mehmast, glad to help.