topic Re: Trouble populating a ComboBox in a VB.NET Windows Form in .NET Forum

Trouble populating a ComboBox in a VB.NET Windows Form

JBerns — Mon, 12 Sep 2022 20:46:40 GMT

Community,

I am developing a VB.NET add-in (DLL) for AutoCAD.

I have a Windows Form with a ComboBox on it.

For debugging purposes, I have manually added items to the ComboBox within the main subroutine.

cboSelCust.Clear cboSelCust.Items.Add("ABC") cboSelCust.Items.Add("DEF")

During debugging, the ComboBox shows that it has two items:

However, when I show the dialog box,

' Declare form and show it Dim myForm As New MainForm Autodesk.AutoCAD.ApplicationServices.Application.ShowModalDialog(myForm)

the ComboBox is empty.

I hope it is something simple that I have overlooked to get the names to show in the ComboBox.

Thanks for your time and attention. I look forward to your replies.

Regards,

Jerry

Re: Trouble populating a ComboBox in a VB.NET Windows Form

_gile — Mon, 12 Sep 2022 21:18:01 GMT

Hi,

Try setting the selected index:

cboSelCust.SelectedIndex = 1

You should also pay attention to the ComboBox.DropDownStyle, it should be ComboBoxStyle.DropDownList if you do not want an editable text portion.

Re: Trouble populating a ComboBox in a VB.NET Windows Form

norman.yuan — Mon, 12 Sep 2022 22:27:46 GMT

Where these lines of code runs:

cboSelCust.Clear cboSelCust.Items.Add("ABC") cboSelCust.Items.Add("DEF")

That is, you'd better show more code where above lines are included.

Also, where "Select a customer" comes from in the combobox? If it is not entered by you after the form shows), then you must have code somewhere does that, which replaces your hard-coded 2 items in the combo box. So, you really examine your code carefully, or post all the code related to the form being populated.

Re: Trouble populating a ComboBox in a VB.NET Windows Form

JBerns — Tue, 13 Sep 2022 13:35:02 GMT

The majority of my code is functioning correctly, so I did not post all of it.

After posting this message, I did some more testing.

I double-clicked the form which created the MainForm_Load function. I thought the form was being initialized and loaded, but apparently not.

After placing this line of code:

cboSelCust.DataSource = lstCustomernames

in the MainForm_Load, the ComboBox list was populated as expected.

So my confusion is then how to create a user defined command (PDF_DXF2) and then open the dialog box when the command starts.

If it is of benefit, I will show the condensed version of the code I have so far, which is now working, but I am not sure if I am initializing and loading correctly.

Imports Autodesk.AutoCAD.ApplicationServices Imports Autodesk.AutoCAD.DatabaseServices Imports Autodesk.AutoCAD.Runtime Imports Autodesk.AutoCAD.EditorInput Imports Autodesk.AutoCAD.Geometry Imports System.Windows.Forms Imports System.Data.OleDb Imports System.Data.Sql Imports System.Data Imports System.Data.SqlClient Imports System.DateTime Imports System.Drawing Imports System.IO Public Class MainForm Public strCustomerName As String Private lstCustomernames As New List(Of String) <CommandMethod("PDF_DXF2")> Public Sub IntializeUserForm() ' Declare form and show it Dim myForm As New MainForm Autodesk.AutoCAD.ApplicationServices.Application.ShowModalDialog(myForm) End Sub Function GetPNCatalogs() As String ' Returns a string, such as "ProNest14" ' This code is working End Function Sub GetCustomerNamesFromSql() ' Declare the ProNest catalog name as a string Dim PNcatalog As String ' Get the largest catalog from the ProNest database on the ENG server PNcatalog = GetPNCatalogs() ' Gets customer names from a SQL database and stores the names in a List(of Strings) variable 'This code is working End Sub Private Sub BtnContinue_Click(sender As Object, e As EventArgs) Handles btnContinue.Click MsgBox("You selected the Continue button.") End Sub Private Sub BtnCancel_Click(sender As Object, e As EventArgs) Handles btnCancel.Click MsgBox("You selected the Cancel button.") Me.Close() End Sub Private Sub MainForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load ' Get Customer data from SQL database GetCustomerNamesFromSql() ' Assign customer names to ComboBox cboSelCust.DataSource = lstCustomernames End Sub End Class

If you need to see the full VS project files, I can provide it.

Thank you all for your feedback.

Regards,

Jerry

Re: Trouble populating a ComboBox in a VB.NET Windows Form

norman.yuan — Wed, 14 Sep 2022 14:10:43 GMT

In your basic showing UI case, the rule of thumb is to separate the UI code (i.e. class MainForm here) from AutoCAD operation: the form should no nothing about whether it is called from AutoCAD or not. So, you do not put <CommandMethod> in the form class.

I usually structure my simple Acad plugin in this way:

MyCommands.cls - which is decorated with <Assembly: CommandClass()> and contains all methods decorated by <CommandMethod()>.

A few classes for specific AutoCAD operations, such as

TitleBlockUpdate.cls

PdfCreation.cls

Then most likely one or more common utility classes

CadUtilities.cls

Then the UI classes

MainForm.cls

TitleBlockForm.cls

PdfOutputForm.cls

All the operations run from MyCommands.cls:

<CommandMethod("TitleBlock">

Public Shared Sub DoTitleBlock()

Dim tb As New TitleBlockUpdate()

tb.DoWork() '' Which could show its own UI

End Sub

<CommandMethod("MyPdf")>

Public Shared Sub CreatePdfForClient()

'' Get client name from MainForm

Dim clientName As String

Using frm As MainForm = New MainForm()

If Application.ShowModalDialog(frm)==DialogResult.OK Then

clientName=frm.SelectedCleint

End If

End Using

If String.IsNullOrEmpty(clientName) Then Exit Sub

'' Assume the PdfCreation class requires a client name in its constructor

Dim pdtTool As New PdfCreation(clientName)

'' inside this process, more UIs can be showed up, but the MyCommands class does not need to know

pdfTool.CreatePdfSet()

End Sub

<CommandMethod("xxxxx")>

Public Shared Sub XXXXXXX()

... ...

End Sub

As you can see, each class does its own work and the MyCommands.cls is like a "switch board" to start each operation as a command by newing operation class and calling its exposed public method, but it does not need to know what the operation classes do.

Hope this gives some ideas.

Re: Trouble populating a ComboBox in a VB.NET Windows Form

JBerns — Wed, 14 Sep 2022 16:02:14 GMT

@norman.yuan and @_gile,

Thank you both for the information you provided. I hope to understand it more as I continue to learn AutoCAD .NET add-in development.

Regards,

Jerry