Importing data from text file in VB.NET - vb.net

Question

So, I am trying to develop a book database. I have created a table with 11 columns which populates a DGV, where only 6 columns are showed. The full data of each book is shown in a lower part of the form, where I have textboxes, which are bounded (BindingSource) to the table, that change as I move in the DGV.
Now, what I want to do is to have the posibility to export/import data from a file.
I have accomplished the exporting part with the following code:
Private Sub BtnExport_Click(sender As Object, e As EventArgs) Handles BtnExport.Click
Dim txt As String = String.Empty
For Each row As DataGridViewRow In DbdocsDataGridView.Rows
For Each cell As DataGridViewCell In row.Cells
'Add the Data rows.
txt += CStr(cell.Value & ","c)
Next
'Add new line.
txt += vbCr & vbLf
Next
Dim folderPath As String = "C:\CSV\"
File.WriteAllText(folderPath & "DataGridViewExport.txt", txt)
End Sub
However, I can't manage to import from the txt. What I've tried is this: https://1bestcsharp.blogspot.com/2018/04/vb.net-import-txt-file-text-to-datagridview.html
It works perfectly if you code the table and it populates de DGV without problem. I can't see how should I adapt that code to my need.
Private Sub BtnImport_Click(sender As Object, e As EventArgs) Handles BtnImport.Click
DbdocsDataGridView.DataSource = table
Dim filas() As String
Dim valores() As String
filas = File.ReadAllLines("C:\CSV\DataGridViewExport.txt")
For i As Integer = 0 To filas.Length - 1 Step +1
valores = filas(i).ToString().Split(",")
Dim row(valores.Length - 1) As String
For j As Integer = 0 To valores.Length - 1 Step +1
row(j) = valores(j).Trim()
Next j
table.Rows.Add(row)
Next i
End Sub
That is what I've tried so far, but I always have an exception arising.
Thanks in advance to anyone who can give me an insight about this.

Answer 1

The DataTable class has built-in methods to load/save data from/to XML called ReadXml and WriteXml. Take a look at example which uses the overload to preserve the schema:
Private ReadOnly dataGridViewExportPath As String = IO.Path.Combine("C:\", "CSV", "DataGridViewExport.txt")
Private Sub BtnExport_Click(sender As Object, e As EventArgs) Handles BtnExport.Click
table.WriteXml(path, XmlWriteMode.WriteSchema)
End Sub
Private Sub BtnImport_Click(sender As Object, e As EventArgs) Handles BtnImport.Click
table.ReadXml(path)
End Sub
While users can manually edit the XML file that is generated from WriteXML, I would certainly not suggest it.

Answer 2

This is code which writes to a text file:
speichern means to save.
Note that I use a # in my example for formatting reasons. When reading in again, you can find the # and then you know that and that line is coming...
And I used Private ReadOnly Deu As New System.Globalization.CultureInfo("de-DE") to format the Date into German format, but you can decide yourself if you want that. 🙂
Note that I'm using a FileDialog that I downloaded from Visual Studio's own NuGet package manager.
Private Sub Button_speichern_Click(sender As Object, e As EventArgs) Handles Button_speichern.Click
speichern()
End Sub
Private Sub speichern()
'-------------------------------------------------------------------------------------------------------------
' User can choose where to save the text file and the program will save it .
'-------------------------------------------------------------------------------------------------------------
Dim Path As String
Using SFD1 As New CommonSaveFileDialog
SFD1.Title = "store data in a text file"
SFD1.Filters.Add(New CommonFileDialogFilter("Textdatei", ".txt"))
SFD1.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
If SFD1.ShowDialog() = CommonFileDialogResult.Ok Then
Path = SFD1.FileName & ".txt"
Else
Return
End If
End Using
Using textfile As System.IO.StreamWriter = My.Computer.FileSystem.OpenTextFileWriter(Path, True, System.Text.Encoding.UTF8)
textfile.WriteLine("Timestamp of this file [dd.mm.yyyy hh:mm:ss]: " & Date.Now.ToString("G", Deu) & NewLine & NewLine) 'supposed to be line break + 2 blank lines :-)
textfile.WriteLine("your text")
textfile.WriteLine("#") 'Marker
textfile.Close()
End Using
End Sub
Private Sub FormMain_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing
speichern()
End Sub
And this is to read from a text file:
'read all Text
Dim RAT() As String = System.IO.File.ReadAllLines(Pfad, System.Text.Encoding.UTF8)
If RAT.Length = 0 Then Return Nothing
For i As Integer = 0 To RAT.Length - 1 Step 1
If RAT(i) = "#" OrElse RAT(i) = "" Then Continue For
'do your work here with (RAT(i))
Next