Updating A DataGridView Cell Incrementally - vb.net

Question

I'm currently having a slight issue duplicating a row and incrementing the sequence number.
So based on a button click, this is how I'm duplicating row 0, duplicated only one time per click.
Dim dr As DataRow
For n As Integer = 0 To 0 ' how many dupes you want
dr = tbl.NewRow
For c As Integer = 0 To tbl.Columns.Count - 1 ' copy data from 0 to NewRow
dr.Item(c) = tbl.Rows(0).Item(c)
Next
tbl.Rows.Add(dr) ' add NewRow to datatable
Next n
Here's how I'm creating the sequence number, pads with leading zeros, which seems to increment, but only after I click the duplicate button, so essentially the last row added, it the duplicated row 0, but doesn't represent the new sequence number needed.
'UPDATE SEQUENCE NUMBER
i += 1
Dim value As Integer = i
Dim r As Integer
Dim decimalLength1 As Integer = value.ToString("D").Length + 7
Dim decimalLength2 As Integer = value.ToString("D").Length + 6
Dim decimalLength3 As Integer = value.ToString("D").Length + 5
Dim decimalLength4 As Integer = value.ToString("D").Length + 4
If i >= 0 And i <= 9 Then
'1 TO 9 FORMAT
DataGridView1.CurrentCell = DataGridView1.CurrentRow.Cells("sequence")
DataGridView1.Item(73, r).Value = value.ToString("D" + decimalLength1.ToString())
'Debug.Print(value.ToString("D" + decimalLength1.ToString()))
ElseIf i >= 10 And i <= 99 Then
'10 TO 99 FORMAT
DataGridView1.CurrentCell = DataGridView1.CurrentRow.Cells("sequence")
DataGridView1.Item(73, r).Value = value.ToString("D" + decimalLength2.ToString())
'Debug.Print(value.ToString("D" + decimalLength1.ToString()))
ElseIf i >= 100 And i <= 999 Then
'100 TO 999 FORMAT
DataGridView1.CurrentCell = DataGridView1.CurrentRow.Cells("sequence")
DataGridView1.Item(73, r).Value = value.ToString("D" + decimalLength3.ToString())
'Debug.Print(value.ToString("D" + decimalLength1.ToString()))
ElseIf i >= 1000 And i <= 9999 Then
'1000 TO 9999 FORMAT
DataGridView1.CurrentCell = DataGridView1.CurrentRow.Cells("sequence")
DataGridView1.Item(73, r).Value = value.ToString("D" + decimalLength4.ToString())
'Debug.Print(value.ToString("D" + decimalLength1.ToString()))
End If
Row 0 will always have a sequence number of 1, so in theory I need to start incrementing at 2.
Suggestions? Is there a better/cleaner way of doing this?
UPDATE 2
Dim startSeq As Integer = Convert.ToInt32(tbl.Rows(0).Item(73))
MsgBox("startSeq = " & startSeq)
For n As Integer = 0 To NumericUpDown1.Value - 1
MsgBox("n = " & n)
dr = tbl.NewRow
For c As Integer = 0 To tbl.Columns.Count - 1
dr.Item(c) = tbl.Rows(0).Item(c)
If c = "73" Then ' if this is the SEQ column,
' add the current seq val to the seq column
dr.Item(c) = (startSeq + n).ToString("00000000")
End If
Next c
tbl.Rows.Add(dr)
Next n

Answer 1

It seems like you should be able to add the sequencer as you create the duplicates. Perhaps make it a method and pass the index of the column which has the sequence string. Something like:
Private Sub DuplicateRows(ColIndx As Integer,
Dupes As Integer)
' start value is Row(0) + 1
Dim startSeq As Integer = Convert.ToInt32(tbl.Rows(0).Item(ColIndx )) + 1
For n As Integer = 0 to Dupes -1
dr = tbl.NewRow
For c As Integer = 0 To tbl.Columns.Count - 1
If c = ColIndx Then ' if this is the SEQ column,
' add the current seq val to the seq column
dr.Item(c) = (startSeq + n).ToString("00000000")
Else
' otherwise copy the data from Row(0)
dr.Item(c) = tbl.Rows(0).Item(c)
End If
Next c
tbl.Rows.Add(dr)
Next n
End Sub
This should initialize each new row with an incremented counter. Is there a better/cleaner way of doing this
a) you should be adding to the DataTable, not the DGV if it is bound
b) (startSeq + n).ToString("00000000") should work to do the padding etc instead of that ugly block of code.
c) Use Option Strict On. If c = "73" ... is nonsense which makes the compiler guess at your intentions. Its is bug food.
d) Hardcoding "73" may work this time, but previously you said it could be anywhere. The code below finds the sequence column based on the name so it can appear anywhere. Rather than a form level var, you could find it just before you make the dupes or even in the Dupes procedure.
e) Dim startSeq As Integer = Convert.ToInt32(tbl.Rows(0).Item(73)) if you examine the answer above, this should be ... + 1 to increment the first value.
Usage:
Private tbl As DataTable ' table loaded from flat file
Private SeqColIndex As Integer ' assigned somewhere to
' point to the "sequence" column
' method to load data
Dim connstr = "Provider=Microsoft.ACE.OLEDB.12.0;..."
Using cn As New OleDbConnection(connstr)
...
End Using
' FIND the sequence column for this session
For n = 0 To tbl.Columns.Count - 1
If tbl.Columns(n).ColumnName.ToLowerInvariant = "sequence" Then
SeqColIndex = n
Exit For
End If
Next
' later to add some rows
Private Sub ButtonAddRow_Click(...
DuplicateRows(SeqColIndex, NumericUpDown1.Value)
End Sub