How to export data from data grid view to pdf in vb - vb.net

Question

I had to delete the previous question to re-evaluate my code properly. The last time I tried to print but it got confusing for me, So I did more research on how to export to pdf and wrote the code for it. When I run the program, I was able to save the pdf as it prompted me but after saving the file, the error popped up and read as follows:
System.NullReferenceException: 'Object reference not set to an instance of an object.'
System.Windows.Forms.DataGridViewCell.Value.get returned Nothing.
This is my code for the export button:
Private Sub btnPrint_Click(sender As Object, e As EventArgs) Handles btnPrint.Click
SaveFileDialog1.ShowDialog()
If SaveFileDialog1.FileName = "" Then
MsgBox("enter filename to create pdf", vbExclamation)
Else
ExportDataToPDFTable
MsgBox("PDF file successfully created!", vbInformation)
End If
End Sub
Private Sub ExportDataToPDFTable()
Dim paragraph As New Paragraph
Dim doc As New Document(iTextSharp.text.PageSize.A4, 40, 40, 40, 10)
Dim wri As PdfWriter = PdfWriter.GetInstance(doc, New FileStream(SaveFileDialog1.FileName + ".pdf", FileMode.Create))
Dim font12Bold As New iTextSharp.text.Font(iTextSharp.text.Font.FontFamily.HELVETICA, 8.0F, iTextSharp.text.Font.BOLD, BaseColor.BLACK)
Dim font12Normal As New iTextSharp.text.Font(iTextSharp.text.Font.FontFamily.HELVETICA, 8.0F, iTextSharp.text.Font.NORMAL, BaseColor.BLACK)
doc.Open()
Dim PdfTable As New PdfPTable(9)
PdfTable.TotalWidth = 490.0F
PdfTable.LockedWidth = True
Dim widths As Single() = New Single() {0.3F, 1.0F, 2.0F, 1.0F, 1.0F, 0.5F, 1.0F, 1.0F, 1.0F}
PdfTable.SetWidths(widths)
PdfTable.HorizontalAlignment = 1
PdfTable.SpacingBefore = 2.0F
Dim PdfCell As PdfPCell = Nothing
PdfCell = New PdfPCell(New Phrase(New Chunk("id", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Center
PdfTable.AddCell(PdfCell)
PdfCell = New PdfPCell(New Phrase(New Chunk("date", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Center
PdfTable.AddCell(PdfCell)
PdfCell = New PdfPCell(New Phrase(New Chunk("brand", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Left
PdfTable.AddCell(PdfCell)
PdfCell = New PdfPCell(New Phrase(New Chunk("size", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Left
PdfTable.AddCell(PdfCell)
PdfCell = New PdfPCell(New Phrase(New Chunk("selling unit price", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Left
PdfTable.AddCell(PdfCell)
PdfCell = New PdfPCell(New Phrase(New Chunk("cost unit price", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Left
PdfTable.AddCell(PdfCell)
PdfCell = New PdfPCell(New Phrase(New Chunk("Quantity", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Left
PdfTable.AddCell(PdfCell)
PdfCell = New PdfPCell(New Phrase(New Chunk("total selling price", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Left
PdfTable.AddCell(PdfCell)
PdfCell = New PdfPCell(New Phrase(New Chunk("total cost price", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Left
PdfTable.AddCell(PdfCell)
PdfCell = New PdfPCell(New Phrase(New Chunk("profit", font12Bold)))
PdfCell.HorizontalAlignment = HorizontalAlignment.Left
PdfTable.AddCell(PdfCell)
Dim dt As DataTable = getDataTable()
If dt IsNot Nothing Then
For rows As Integer = 0 To dt.Rows.Count - 1
For columns As Integer = 0 To dt.Columns.Count - 1
PdfCell = New PdfPCell(New Phrase(dt.Rows(rows)(columns).ToString, font12Normal))
If columns = 4 Or columns = 6 Then
PdfCell.HorizontalAlignment = HorizontalAlignment.Right
Else
If columns = 0 Or columns = 5 Then
PdfCell.HorizontalAlignment = HorizontalAlignment.Center
Else
PdfCell.HorizontalAlignment = HorizontalAlignment.Left
End If
End If
Next
Next
doc.Add(PdfTable)
End If
doc.Close()
End Sub
Private Function getDataTable() As DataTable
Dim DataTable As New DataTable("MyDataTable")
' Dim dataColumn1 As New DataColumn(DataGridView1.Columns(0).HeaderText.ToString, GetType(String))
Dim dataColumn2 As New DataColumn(DataGridView1.Columns(2).HeaderText.ToString, GetType(String))
Dim dataColumn3 As New DataColumn(DataGridView1.Columns(3).HeaderText.ToString, GetType(String))
Dim dataColumn4 As New DataColumn(DataGridView1.Columns(4).HeaderText.ToString, GetType(String))
Dim dataColumn5 As New DataColumn(DataGridView1.Columns(5).HeaderText.ToString, GetType(String))
Dim dataColumn6 As New DataColumn(DataGridView1.Columns(6).HeaderText.ToString, GetType(String))
Dim dataColumn7 As New DataColumn(DataGridView1.Columns(7).HeaderText.ToString, GetType(String))
Dim dataColumn8 As New DataColumn(DataGridView1.Columns(8).HeaderText.ToString, GetType(String))
Dim dataColumn9 As New DataColumn(DataGridView1.Columns(9).HeaderText.ToString, GetType(String))
' Dim dataColumn10 As New DataColumn(DataGridView1.Columns(10).HeaderText.ToString, GetType(String))
' DataTable.Columns.Add(dataColumn1)
DataTable.Columns.Add(dataColumn2)
DataTable.Columns.Add(dataColumn3)
DataTable.Columns.Add(dataColumn4)
DataTable.Columns.Add(dataColumn5)
DataTable.Columns.Add(dataColumn6)
DataTable.Columns.Add(dataColumn7)
DataTable.Columns.Add(dataColumn8)
DataTable.Columns.Add(dataColumn9)
' DataTable.Columns.Add(dataColumn10)
Dim dataRow As DataRow
For i As Integer = 0 To DataGridView1.Rows.Count - 1
dataRow = DataTable.NewRow
' dataRow(DataGridView1.Columns(0).HeaderText.ToString) = DataGridView1.Rows(i).Cells(0).Value.ToString
dataRow(DataGridView1.Columns(2).HeaderText.ToString) = DataGridView1.Rows(i).Cells(2).Value.ToString
dataRow(DataGridView1.Columns(3).HeaderText.ToString) = DataGridView1.Rows(i).Cells(3).Value.ToString
dataRow(DataGridView1.Columns(4).HeaderText.ToString) = DataGridView1.Rows(i).Cells(4).Value.ToString
dataRow(DataGridView1.Columns(5).HeaderText.ToString) = DataGridView1.Rows(i).Cells(5).Value.ToString
dataRow(DataGridView1.Columns(6).HeaderText.ToString) = DataGridView1.Rows(i).Cells(6).Value.ToString
dataRow(DataGridView1.Columns(7).HeaderText.ToString) = DataGridView1.Rows(i).Cells(7).Value.ToString
dataRow(DataGridView1.Columns(8).HeaderText.ToString) = DataGridView1.Rows(i).Cells(8).Value.ToString
dataRow(DataGridView1.Columns(9).HeaderText.ToString) = DataGridView1.Rows(i).Cells(9).Value.ToString
' dataRow(DataGridView1.Columns(10).HeaderText.ToString) = DataGridView1.Rows(i).Cells(10).Value.ToString
Next
DataTable.AcceptChanges()
Return DataTable
End Function
With my IMPORTS:
Imports iTextSharp
Imports iTextSharp.text
Imports iTextSharp.text.pdf
Imports System.IO
The query for retrieving data from the data grid view works fine, but I want the retrieved data from DGV to be exported to pdf once I click the "save as PDF" button. My error is after saving the pdf file, it's where the error has popped up and when opening the pdf file the error says:
screenshot of the error: https://snipboard.io/VF9RKQ.jpg from Adobe PDF
Screenshot of the DGV data after retrieved: https://snipboard.io/r627jz.jpg
I don't know where I went wrong. Why I'm not able to see DGV data on PDF? Did I miss something?

Answer 1

first of all, before doing DataGridView1.Rows(i).Cells(x).Value.ToString you must ensure DataGridView1.Rows(i).Cells(x).Value is not empty :
in getDataTable() replace lines
dataRow(DataGridView1.Columns(x).HeaderText.ToString) = DataGridView1.Rows(i).Cells(x).Value.ToString
by
'note : I simplified 'dataRow(DataGridView1.Columns(x).HeaderText.ToString)'
dataRow(x) = IIF(DataGridView1.Rows(i).Cells(x).Value is nothing, "", DataGridView1.Rows(i).Cells(x).Value.ToString)
IFF statement works like that :
IFF(condition, result if condition is true, result if false) so if cell is empty, datarow will be filled with "".
update : to track errors add try/catch and breakpoint
Try
dataRow(2) = IIF(DataGridView1.Rows(i).Cells(2).Value is nothing, "", DataGridView1.Rows(i).Cells(2).Value.ToString)
dataRow(3) = IIF(DataGridView1.Rows(i).Cells(3).Value is nothing, "", DataGridView1.Rows(i).Cells(3).Value.ToString)
dataRow(4) = IIF(DataGridView1.Rows(i).Cells(4).Value is nothing, "", DataGridView1.Rows(i).Cells(4).Value.ToString)
dataRow(5) = IIF(DataGridView1.Rows(i).Cells(5).Value is nothing, "", DataGridView1.Rows(i).Cells(5).Value.ToString)
dataRow(6) = IIF(DataGridView1.Rows(i).Cells(6).Value is nothing, "", DataGridView1.Rows(i).Cells(6).Value.ToString)
dataRow(7) = IIF(DataGridView1.Rows(i).Cells(7).Value is nothing, "", DataGridView1.Rows(i).Cells(7).Value.ToString)
dataRow(8) = IIF(DataGridView1.Rows(i).Cells(8).Value is nothing, "", DataGridView1.Rows(i).Cells(8).Value.ToString)
dataRow(9) = IIF(DataGridView1.Rows(i).Cells(9).Value is nothing, "", DataGridView1.Rows(i).Cells(9).Value.ToString)
Catch ex As Exception 'put break point here and look at ex value
End Try