Export datatable to Excel (VB window application) - vb.net

Question

So this is what i've tried. It successfully export but there's NO data. Empty excel. I guess i need to put some code to add row and column but i don't know how. I'm new in this.
Try
'Exporting to Excel.
Dim folderPath As String = dtJelo.Rows(0)("jelly").ToString.Trim
Dim filename As String = "JellyDetails" & current_yyyy & current_mon & ".xlsx"
Dim xlApp As Excel.Application
Dim xlWorkBook As Excel.Workbook
Dim xlWorkSheet As Excel.Worksheet
Dim misValue As Object = System.Reflection.Missing.Value
'addrow
xlApp = New Excel.Application
xlWorkBook = xlApp.Workbooks.Add(misValue)
xlWorkSheet = xlWorkBook.Sheets("sheet1")
xlWorkSheet.SaveAs("C:\Users\spongebob\Desktop\" & filename & ".xlsx")
xlWorkBook.Close()
xlApp.Quit()
releaseObject(xlApp)
releaseObject(xlWorkBook)
releaseObject(xlWorkSheet)
MsgBox("Excel file created")
Catch ex As Exception
End Try

Answer 1

I am not exactly sure what you are trying to do here, but here is an example of creating an excel file and populating the cells with some data from an array.
Examples of arrays --> Arrays in Visual Basic
So here is the link to the code that you tried to use. Net-informations.com
You were missing the functions to return the year and day as a string to name the file. Also, you were missing the method releaseObject() from the original code that you used.
Test Code
Imports System
Imports System.Windows.Forms
Imports Microsoft.Office.Interop
Namespace WinFormTestApp
Partial Public Class Form1
Inherits Form
Public Sub New()
Call LoadData()
End Sub
Private Sub LoadData()
Try
'Exporting to Excel.
'Dont know where this dtJelo comes from, so I just assigned a folder variable below.
'Dim folderPath As String = dtJelo.Rows(0)("jelly").ToString.Trim
Dim folderPath As String = "C:\temp\"
Dim filename As String = "JellyDetails" & current_yyyy() & current_mon() & ".xlsx"
Dim xlApp As Excel.Application = New Microsoft.Office.Interop.Excel.Application()
Dim xlWorkBook As Excel.Workbook = xlApp.Workbooks.Add
Dim xlWorkSheet As Excel.Worksheet = CType(xlWorkBook.Worksheets(1), Excel.Worksheet)
'Create an array to populate Excel with
Dim myArray(5) As String
myArray(0) = "This is line number 1"
myArray(1) = "This is line number 2"
myArray(2) = "This is line number 3"
myArray(3) = "This is line number 4"
myArray(4) = "This is line number 5"
myArray(5) = "This is line number 6"
'This is where they are adding the code.
xlWorkSheet.Cells(1, 1) = "Column Header Text"
For xx As Integer = 0 To UBound(myArray)
'Add 2 to xx so that you do not overwrite the Column Header
xlWorkSheet.Cells(xx + 2, 1) = myArray(xx)
Next
xlWorkBook.SaveAs($"{folderPath}{filename}", Excel.XlFileFormat.xlWorkbookDefault)
xlWorkBook.Close(True)
xlApp.Quit()
releaseObject(xlWorkSheet)
releaseObject(xlWorkBook)
releaseObject(xlApp)
'MsgBox("Excel file created")
MessageBox.Show($"Excel file created , you can find the file at {folderPath}{filename}")
Catch ex As Exception
End Try
End Sub
Private Sub releaseObject(ByVal obj As Object)
Try
System.Runtime.InteropServices.Marshal.ReleaseComObject(obj)
obj = Nothing
Catch ex As Exception
obj = Nothing
Finally
GC.Collect()
End Try
End Sub
Private Function current_mon() As String
Try
Return String.Format(Now.Month.ToString, "00")
Catch ex As Exception
Return Nothing
End Try
End Function
Private Function current_yyyy() As String
Try
Return Now.Year.ToString
Catch ex As Exception
Return Nothing
End Try
End Function
End Class
End Namespace
Their Code
Imports Excel = Microsoft.Office.Interop.Excel
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim xlApp As Excel.Application = New Microsoft.Office.Interop.Excel.Application()
If xlApp Is Nothing Then
MessageBox.Show("Excel is not properly installed!!")
Return
End If
Dim xlWorkBook As Excel.Workbook
Dim xlWorkSheet As Excel.Worksheet
Dim misValue As Object = System.Reflection.Missing.Value
xlWorkBook = xlApp.Workbooks.Add(misValue)
xlWorkSheet = xlWorkBook.Sheets("sheet1")
xlWorkSheet.Cells(1, 1) = "Sheet 1 content"
xlWorkBook.SaveAs("d:\csharp-Excel.xls", Excel.XlFileFormat.xlWorkbookNormal, misValue, misValue, misValue, misValue, _
Excel.XlSaveAsAccessMode.xlExclusive, misValue, misValue, misValue, misValue, misValue)
xlWorkBook.Close(True, misValue, misValue)
xlApp.Quit()
releaseObject(xlWorkSheet)
releaseObject(xlWorkBook)
releaseObject(xlApp)
MessageBox.Show("Excel file created, you can find the file d:\csharp-Excel.xls")
End Sub
'YOU WERE MISSING THIS FUNCTION IN YOUR EXAMPLE
Private Sub releaseObject(ByVal obj As Object)
Try
System.Runtime.InteropServices.Marshal.ReleaseComObject(obj)
obj = Nothing
Catch ex As Exception
obj = Nothing
Finally
GC.Collect()
End Try
End Sub
End Class

Answer 2

Here I propose for your addrow only, you can change range "A1" to other range:
'addrow (you can create function for this, with datatable parameter and range parameter to begin)
Dim IncludeLabel As Boolean = True
For xx = 0 To dtJelo.Rows.Count - 1
For yy = 0 To dtJelo.Columns.Count - 1
If IncludeLabel = True Then
If xx = 0 Then
xlWorkSheet.range("a1").Offset(xx,yy).value=dtJelo.Columns(yy).ColumnName
End If
xlWorkSheet.range("a1").Offset(xx+1,yy).value=dtJelo.Rows(xx)(yy)
Else
xlWorkSheet.range("a1").Offset(xx,yy).value=dtJelo.Rows(xx)(yy)
End If
Next
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