Visual Basic 2017 - DataGridView - vb.net

Question

So I am having difficulty with my sub routines. I am creating an app to help with dungeon masters. Part of what my application will do is display several spreadsheets, in separate tabs, containing a list of items and details related to them. I want to reuse several my code instead of writing 20 or so nearly identical sub routines.
Here is my code, I am not sure how to solve my problem.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
loadExcel("C:\Users\secretUserName\source\repos\QUILLandDAGGER\QUILLandDAGGER\bin\Debug\recIntKnowl.xls",dgvRecEntKnowl)
End Sub
Private Sub loadExcel(strFilename As String, dgvView As DataGridView)
Try
Dim MyConnection As OleDb.OleDbConnection
Dim Ds As System.Data.DataSet
Dim MyAdapter As System.Data.OleDb.OleDbDataAdapter
MyConnection = New System.Data.OleDb.OleDbConnection("provider=Microsoft.Jet.OLEDB.4.0;Data Source='strFileName';Extended Properties=Excel 8.0;")
MyAdapter = New System.Data.OleDb.OleDbDataAdapter("select * from [Sheet1$]", MyConnection)
Ds = New System.Data.DataSet
MyAdapter.Fill(Ds)
dgvView.DataSource = Ds.Tables(0)
MyConnection.Close()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub

Answer 1

Build the method like this:
Private Function LoadExcel(ByVal strFilename As String, Optional ByVal SheetName As String = "Sheet1$") As DataTable
Dim SQL As String = "SELECT * FROM [" & SheetName & "]"
Dim result As New DataTable
Using MyConnection As New OleDb.OleDbConnection(), _
MyCommand As New OleDb.OleDbCommand(SQL, MyConnection)
MyConnection.Open()
Using reader As OleDb.OleDbDataReader = MyCommand.ExecuteReader()
result.Load(reader)
End Using
End Using
Return result
End Function
There are numerous improvements in this new code, both great and small. The most important are adding Using blocks, separating the data access from the UI, and designing functions that accept input in order to return a result.
Call it like this:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Try
dgvRecEntKnowl.DataSource = LoadExcel("C:\Users\secretUserName\source\repos\QUILLandDAGGER\QUILLandDAGGER\bin\Debug\recIntKnowl.xls.xls")
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
As to whether this will actually fix anything... that depends on the problem you're having, which wasn't included in the posted question.

Answer 2

Sorry for failing to post my problem. I actually didn't know directly where my problem was and I've spent hours trying to find that.
My first problem was passing the string that contains directly to the file. It's poorly pointing to the file, which I'll resolve and have it point to a sub directory at a later point.
My second problem was with a specific line and I resolved that.
MyConnection = New System.Data.OleDb.OleDbConnection("provider=Microsoft.Jet.OLEDB.4.0;Data Source='C:\Users\seidl\source\repos\QUILLandDAGGER\QUILLandDAGGER\bin\Debug\detect.xls';Extended Properties=Excel 8.0;")
This line of code was my original text and it worked.
MyConnection = New System.Data.OleDb.OleDbConnection("provider=Microsoft.Jet.OLEDB.4.0;Data Source='strFileName';Extended Properties=Excel 8.0;")
Was what I tried and it didn't work. I even removed the ' that surrounded the text and it didn't work.
So it finally clicked with me, to try something I used in Java when writing strings of texts and I needed variables in my lines of text. +
MyConnection = New System.Data.OleDb.OleDbConnection("provider=Microsoft.Jet.OLEDB.4.0;Data Source='" + strFileName + "';Extended Properties=Excel 8.0;")
This ended up working like a charm. I am guessing that OleDbConnection takes in a long string of characters and breaks down the string to read in what is needed. I could be wrong but this is incredibly interesting! It only took a many hours to finally see this.
Joel, I will investigate what you replied with and try and clean up my code. Thank you!