Importing a CSV into a combobox, then changing other things in VB - vb.net

Question

What I want to do is import a CSV file (called fwlist.txt), that looks like this:
modelname,power type,pic,part number,firmware, option1, option 1, etc
End result, i would like a combobox that shows the modelname, and when the model name is selected from the pulldown, it updates various labels and text boxes on the form with other information.
Here's what I have so far:
Dim filename As String = "fwlist.txt"
Dim pwrtype As String
Dim pic As String
Dim partnum As String
Dim lineread As String
Dim FirmwareName As String
Private Sub ReadFirmwaresLoad(sender As Object, e As EventArgs) Handles Me.Load
' Load the items into the NameComboBox list.
Dim ResponseDialogResult As DialogResult
Try
Dim FirmwareStreamReader As StreamReader = New StreamReader(filename)
' Read all the elements into the list.
Do Until FirmwareStreamReader.Peek = -1
lineread = FirmwareStreamReader.ReadLine()
Dim fields As String() = lineread.Split(",")
FirmwareName = fields(0) 'Take First Field
cbFW.Items.Add(FirmwareName)
'Set Text labels based on position in line.
pwrtype = fields(1)
pic = fields(2)
partnum = fields(3)
(...etc through options)
Loop
' Close the file.
FirmwareStreamReader.Close()
Catch ex As Exception
' File missing.
ResponseDialogResult = MessageBox.Show("File not Found!", "File Not Found",
MessageBoxButtons.OK, MessageBoxIcon.Question)
If ResponseDialogResult = DialogResult.OK Then
' Exit the program.
Me.Close()
End If
End Try
End Sub
Private Sub cbFW_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cbFW.SelectedIndexChanged
lblPwrType.Text = pwrtype
lblPic.Text = pic
lblPartNum.Text = parnum
....etc thruogh options
End Sub
This code works, but only sort of. If i select anything from the combo box, it only gives me the information from the very last line of the CSV file - even if its the first entry in the box. I'm pretty sure it's something simple that I'm messing up.. anyone help?

Answer 1

First we read the lines into Firmware objects then we set this List(Of Firmware) as the DataSource of the ComboBox.
Then we handle the SelectedIndexChanged event of the ComboBox which will get the currently selected firmware and loads its data to the TextBox controls.
This is a tested, working example below:
Public Class Firmware
Public Property ModelName As String
Public Property PowerType As String
Public Property Pic As String
Public Property PartNumber As String
Public Property Firmware As String
Public Property Option1 As String
End Class
Public Class MainForm
Private Sub btnLoad_Click(sender As Object, e As EventArgs) Handles btnLoad.Click
Dim lines As String() = Nothing
Try
' Read the file in one step
lines = File.ReadAllLines("fwlist.txt")
Catch ex As Exception
Dim dialogResult As DialogResult = MessageBox.Show(Me, "File not found! Would you like to exit program?", "Error reading file", MessageBoxButtons.YesNo, MessageBoxIcon.Error, MessageBoxDefaultButton.Button2)
If dialogResult = DialogResult.Yes Then
Me.Close()
End If
Exit Sub
End Try
Dim firmwares As List(Of Firmware) = New List(Of Firmware)
For Each line As String In lines
Dim rawData As String() = line.Split({","}, StringSplitOptions.None)
' Create Firmware object from each line
Dim firmware As Firmware = New Firmware() With
{
.ModelName = rawData(0),
.PowerType = rawData(1),
.Pic = rawData(2),
.PartNumber = rawData(3),
.Firmware = rawData(4),
.Option1 = rawData(5)
}
' We store the read firmwares into a list
firmwares.Add(firmware)
Next
' Set the list as the data source of the combobox
' DisplayMember indicates which property will be shown in the combobox
With cboModelNames
.DataSource = firmwares
.DisplayMember = "ModelName"
End With
End Sub
Private Sub cboModelNames_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cboModelNames.SelectedIndexChanged
RefreshForm()
End Sub
Private Sub RefreshForm()
' Get the selected item as Firmware object
Dim currentFirmware As Firmware = DirectCast(cboModelNames.SelectedItem, Firmware)
' Refresh all the textboxes with the information
With currentFirmware
txtPowerType.Text = .PowerType
txtPic.Text = .Pic
txtPartNumber.Text = .PartNumber
txtFirmware.Text = .Firmware
txtOption1.Text = .Option1
End With
End Sub
End Class

Answer 2

Every time you set the value of a variable like pwrtype, its old value is thrown away and there is no way to get it back. And even if you did save multiple values for each variable, you would need a way to figure out which value goes with the currently selected item in the combo box. To resolve these two issues you need:
a way to group values from the same line together
a way to save all values read from the file, not just the most recent ones
Let's start with the first issue, grouping values together. In the example code below, I created a Structure type called FirmwareInfo to serve that purpose. Each FirmwareInfo has its own pwrtype, pic, etc.
The other piece of the puzzle that you are missing is a way to save more than one Firmware. The easiest way to do this is to add each FirmwareInfo to the combo box's item list, instead of adding just the display string. The combo box will convert each item to a string in the UI; the ToString() method tells it how you want this conversion to be done.
I haven't run this example code so I can't guarantee there aren't mistakes in there, but hopefully it's enough to show the general idea.
Dim filename As String = "fwlist.txt"
Structure FirmwareInfo
Public pwrtype As String
Public pic As String
Public partnum As String
Public FirmwareName As String
Public Overrides Function ToString() As String
Return FirmwareName
End Function
End Structure
Private Sub ReadFirmwaresLoad(sender As Object, e As EventArgs) Handles Me.Load
' Load the items into the NameComboBox list.
Dim ResponseDialogResult As DialogResult
Try
Dim FirmwareStreamReader As StreamReader = New StreamReader(filename)
' Read all the elements into the list.
Do Until FirmwareStreamReader.Peek = -1
Dim lineread = FirmwareStreamReader.ReadLine()
Dim fields As String() = lineread.Split(",")
Dim info As New FirmwareInfo With {
.FirmwareName = fields(0),
.pwrtype = fields(1),
.pic = fields(2),
.partnum = fields(3)
}
cbFW.Items.Add(info)
Loop
' Close the file.
FirmwareStreamReader.Close()
Catch ex As Exception
' File missing.
ResponseDialogResult = MessageBox.Show("File not Found!", "File Not Found",
MessageBoxButtons.OK, MessageBoxIcon.Question)
If ResponseDialogResult = DialogResult.OK Then
' Exit the program.
Me.Close()
End If
End Try
End Sub
Private Sub cbFW_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cbFW.SelectedIndexChanged
Dim currentInfo = DirectCast(cbFW.SelectedItem, FirmwareInfo)
lblPwrType.Text = currentInfo.pwrtype
lblPic.Text = currentInfo.pic
lblPartNum.Text = currentInfo.parnum
' ....etc through options
End Sub