Inherited DataGridView Column Double Up

[Brent Burgess]

I am creating a little timesheet app, and I have created my own custom datagridview. I have got it all setup and it looks fine when I first add the control to the form.

When I debug the app for the first time after adding, I get a double up of columns. Does anyone know what causes this?

[jmcilhinney]

Are the columns added in code? Have you actually checked whether the code is executed twice?

[Meestor_X]

I'm having this same problem.
In my app, Columns are manually added in the New() sub.
In design view, it has the right number of columns, but when I run the app, it doubles up the columns.
Does vb run the New() sub twice?
I even added Columns.Clear in the New() sub, in case the New() sub was being run twice, but that didn't fix it.
The form designer code shows only the 1st set of columns.

[Meestor_X]

Perhaps this is part of the problem?
The original URL is missing and I don't understand what needs to be done to fix this problem.

[dunfiddlin]

Nope. If there was a problem with inheriting DataGridView then it's been fixed. I'm not getting any problems with it so it's gotta be in your code somewhere. I'd suggest you show us at least you New Sub!

[Meestor_X]

Nope. If there was a problem with inheriting DataGridView then it's been fixed. I'm not getting any problems with it so it's gotta be in your code somewhere. I'd suggest you show us at least you New Sub!

That's good news. Probably something stupid on my end then...

Public Sub New()
        InitializeComponent()
 
        VirtualMode = True
        Dim HexColumns(17) As DataGridViewTextBoxColumn
        For i As Integer = 0 To 17
            HexColumns(i) = New DataGridViewTextBoxColumn
            With HexColumns(i)
                .HeaderText = Hex(i - 1)
                .Width = 25
                .SortMode = DataGridViewColumnSortMode.NotSortable
                .Name = .HeaderText
            End With
        Next
        Columns.Clear()
        Columns.AddRange(HexColumns)
 
        With Columns(0)
            .HeaderText = "Addr"
            .HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
            .Width = 75
        End With
 
        With Columns(17)
            .HeaderText = "Text"
            .HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
            .Width = 150
        End With
    End Sub

[Meestor_X]

This sounds like the same problem, but I don't understand the solution.
Another link to another solution

If I add "If Me.DesignMode Then" to the column creation section of the New() Sub, no columns get created at designtime or runtime.
If I add "If Not Me.DesignMode Then" to the column creation section, columns get created twice.

Interestingly, the extra columns don't have the alignment set as I set them in the New() Sub.

First pic is design mode

2nd is running the program. Note the alignment of the HeaderText...

[dunfiddlin]

What happens if you delete InitializeComponent() from the New sub?

[Meestor_X]

What happens if you delete InitializeComponent() from the New sub?

I get the warning:
"Warning 1 'Public Sub New()' in designer-generated type 'AndysControls.HexDataGridView' should call InitializeComponent method."
It also doesn't fix the problem.

Here's another discussion of this problem.

Did you have a look at the links I posted?

You said earlier:

Nope. If there was a problem with inheriting DataGridView then it's been fixed. I'm not getting any problems with it so it's gotta be in your code somewhere.

Are you able to make an inherited DataGridView with programmatically-created columns that doesn't show the problem I and the OP are experiencing?
If so, can you show me your code so I can see where I'm going wrong?

[dunfiddlin]

I can but I haven't worked it up to a full custom control, just as an additional class instanced at runtime. If you can zip up your control project and attach it here, I'll be happy to see what can be done.

[Meestor_X]

Ok, got it sorted out. It sure was a difficult solution to find!

Had to add:

<System.ComponentModel.DesignerSerializationVisibilityAttribute(System.ComponentModel.DesignerSerializationVisibility.Hidden)> _
    Overloads ReadOnly Property Columns As DataGridViewColumnCollection
        Get
            Return MyBase.Columns
        End Get
    End Property

In my class that inherits the DataGridView.
Still the designer (re)creates all the columns, but at least it doesn't add them to the DataGridView.
I'm not sure if there would be a way to use this attribute to also supress the duplication of the Columns in the designer, just to really completely correct this problem...

WHEW!

[techgnome]

put a break point on this line:
Columns.Clear()
BEFORE it runs... check to see what the Columns.Count is...

then run that ONE line... go no further...
before this line:
Columns.AddRange(HexColumns)
again check to see what the Columns.Count is... Something tells me that it hasn't changed... clearing the columns does NOT (if I remember right) REMOVE the columns... it jsut clears them out, sets the headers to empty, removes databindings, data, etc...

It's like using Textbox.Clear... doesn't actually remove the textbox.. it just clears it out.

If you want to remove the existing columns, then that's what you need to do... REMOVE the columns... THEN add the new ones.

-tg

[Meestor_X]

Please see the previous post AND all my links.

The problem is the designer is creating the columns and adding them in addition to me programmatically adding the columns.
My previous post shows the solution which works.

[techgnome]

I did read all of the posts... and I keyed in on this:
Still the designer (re)creates all the columns, but at least it doesn't add them to the DataGridView.

which tells me the problem is still there but you've managed to gloss over it... fine, what ever. your project.

-tg

[Meestor_X]

which tells me the problem is still there but you've managed to gloss over it... fine, what ever. your project.

Ok, I'll bite.
Your solution says to remove the columns and that Columns.Clear() does not do this. So what would actually REMOVE the columns then?
If you look at the form1.designer file, you can see where it recreates all the columns as I was saying. The only way I've found to stop this is my solution, but I'm open to other suggestions...