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Removing items from a listbox in VB?

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nico8002 -  
Hello everyone,

I have a Select that displays the results in a listbox and I would like to be able to remove items from this listbox.

I would like to click on a name in my list and then click on a "remove" button.

Do you have any code ideas??

Thank you in advance.

Configuration: Windows XP / Internet Explorer 6.0

13 answers

  1. nico8002 Author
    Oh, but actually I don't want to remove it from my database, I just want to remove it from my list.
    Do you have any idea how to do that?
    Because I'm starting with VB, I'm a bit in the dark :s
    1
    1. AnthonyG
      On your delete button, you can remove the record from your database with an SQL query like:
      "DELETE * FROM YourTable WHERE YourTable.Name = ""& Me.ListBox.Text "";"
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      1. sky
        too stupid
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    2. chrij
      Hello,
      you need to get the index of the items to be removed (index i for example).

      Then, you can do: 
      ListBox1.Items.RemoveAt(i)
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      1. nico8002 Author
        I did this

        Dim ItemObject(9) As System.Object
        Dim i As Integer
        For i = 0 To 9
        ItemObject(i) = "Item" & i
        Next i
        LB_ListeMachines.Items.RemoveAt(i)

        But when I run my application and click the button, it highlights in yellow the line I highlighted.
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    3. AnthonyG
      I'm not very imaginative this morning, but you could create a second table similar to the first in which you would make a copy of your source table. To remove elements, you would delete them as I suggested above.
      It's a very dirty solution, I agree, and you must certainly be able to find better.
      You could also consider storing those you want to keep in another table, instead of deleting what you no longer want, but that's hardly better.
      What use do you envision for your cleaned-up list, exactly?
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      2. nico8002 Author
        Well, actually I have a database with a list of machines
        and I will need to send a file to certain machines
        so I display the machines (present in my database) in a listbox
        and I would like to remove from the listbox to send my file only to the ones I want to send it to.
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        1. nico8002 Author
          Chrij, I did this

          Dim ItemObject(9) As System.Object
          Dim i As Integer
          For i = 0 To 9
          ItemObject(i) = "Item" & i
          Next i
          LB_ListeMachines.Items.RemoveAt(i)

          but when I run my application and click the button, it highlights the line I highlighted in yellow.
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          1. chrij
            What error does it give you?

            With what you just wrote, you will remove the object whose index is 9 from your list (the last i = 9).

            According to what you wrote at the beginning, you want to remove what you select from the list. If that's the case, you can do: 
            For Each item In ListBox1.SelectedItems ListBox1.Items.Remove(item) Next
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          2. nico8002 Author
            I put what you just gave me:

            For Each item In LB_ListeMachines.SelectedItems
            LB_ListeMachines.Items.Remove(item)
            Next

            and it always highlights in yellow the line you underlined and tells me this:

            Cannot modify the item collection when the DataSource property is set.
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          3. chrij
            try to close your DataSource before deleting:

            ObjectDataSet.Clear()
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          4. nico8002 Author
            Dim ObjetDataSet As DataSet
            ObjetDataSet.Clear()
            For Each item In LB_ListeMachines.SelectedItems
            LB_ListeMachines.Items.Remove(item)
            Next

            I did this, but it highlights in green what I underlined and tells me:
            "The variable 'ObjetDataSet' is used before it has been assigned a value. A null reference exception may occur at runtime."
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          5. chrij
            Normal for the error.
            You shouldn't create the dataset object.
            You must have somewhere a "Data something" that is open (that's what the error said "Cannot modify the element collection when the DataSource property is set". You need to close it to modify the elements of the Listbox.
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        2. nico8002 Author
          Actually, it's not working,

          Dim DT As New DataTable
          DT.Clear()
          For Each item In LB_ListeMachines.SelectedItems
          LB_ListeMachines.Items.Remove(item)
          Next

          So I did what you told me for my datasource, but it still highlights the same thing and gives me the same error.
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          1. chrij
            I just did a quick test that seems to work: 
            Dim liste As ListBox.SelectedIndexCollection liste = ListBox1.SelectedIndices For Each item In liste ListBox1.Items.RemoveAt(item) Next


            Normally, it only deletes the selected items.
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            1. nico8002 Author
              well it always takes away my entire list
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            2. nico8002 Author
              Dim liste As ListBox.SelectedIndexCollection
              liste = LB_ListeMachines.SelectedIndices
              For Each item In liste
              LB_ListeMachines.Items.RemoveAt(item)
              Next

              I put that…
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            3. chrij
              Did you put it in a function?
              Don't you have anything else that selects the elements from your list?

              When I did my test, I selected the elements with the mouse, then I deleted the selected item.

              Do you have only one element selected at a time?
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            4. nico8002 Author
              I have a "show" button to put all the names from my database into the list box.
              Then, in my database, each machine has a sector; there are 2 in my case.
              So I have a checkbox that shows the machines from one of the 2 sectors and another one that does the opposite.
              So nothing selects my items.
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            5. nico8002 Author
              Do I need to put code in the function of my listbox?
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          2. lermite222 Contributor
            Hello,
            Apparently you are in VB.Net, I do not know the syntax but in VB6 I would write... 
             For i = ListBox1.Count - 1 To 0 Step -1 If ListBox1.Selected(i) Then ListBox1.RemoveItem (i) i = i - 1 End If Next i

            Your turn to transcribe in .net
            A=

            --
            Experience teaches more surely than advice. (André Gide)
            If you bump into a pot and it sounds hollow, it's not necessarily the pot that is empty. ;-)(Confucius)
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            1. nico8002 Author
              OK
              I'm going to try to transcribe all of that
              Thank you
              0
            2. lermite222 Contributor
              In re-reading your main post, you could directly remove the line in the click event of the listBox 
               ListBox1.RemoveItem (ListBox1.ListIndex)
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          3. chrij
            Well, the good thing is that we're working with the same version of vb.
            The downside is that I don't have any issues.

            Can you show me the function that fills your listbox?
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            1. nico8002 Author
              ```vb Private Sub B_Afficher_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles B_Afficher.Click

              Dim DT As New DataTable
              DT.Clear()
              Dim oleDbConnex As New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data source=C:\...\BDD.mdb")
              Dim oleCmd As New OleDb.OleDbCommand("SELECT NomMachine FROM Machine", oleDbConnex)

              Try
              Dim TA As New OleDb.OleDbDataAdapter(oleCmd)
              TA.Fill(DT)
              With LB_ListeMachines
              .ValueMember = "NomMachine"
              .DisplayMember = "NomMachine"
              .DataSource = DT
              End With
              Catch ex As Exception
              MessageBox.Show("Unable to establish a connection to the database!! " & ex.Message)
              End Try

              For i = 0 To LB_ListeMachines.Items.Count - 1
              LB_ListeMachines.SetSelected(i, False)
              Next

              End Sub ```
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            2. lermite222 Contributor
              Since it's fine... I don't see what the way of filling the listbox has to do with the question??
              And since you have no problem, try translating the function I showed above into .net. :D
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            3. nico8002 Author
              Well, I did it, but it also deletes my entire list :/

              Here is how I translated it :

              For i = LB_ListeMachines.Items.Count - 1 To 0 Step -1
              If LB_ListeMachines.SelectedItems(i) Then
              LB_ListeMachines.Items.RemoveAt(i)
              i = i - 1
              End If
              Next i
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            4. chrij
              Here is the Hermite function 222 in VB2008: 
              For i = ListBox1.Items.Count - 1 To 0 Step -1 If ListBox1.GetSelected(i) Then ListBox1.Items.RemoveAt(i) i = i - 1 End If Next i
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            5. nico8002 Author
              I put them, it always deletes everything :'(
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          4. chrij
            I found a link that offers a solution to fill a listbox from a database.
            https://codes-sources.commentcamarche.net/

            Basically, you would need to put: 
             TA.Fill(DT) oleDbConnex.Close() for i=0 to DT.Rows.Count -1 LB_ListeMachines.Items.Add(DT.Rows(i)("NomColonne").toString) Next


            I don't have a database on hand to test...
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            1. nico8002 Author
              Well, I filled my listbox
              it's good, everything is displayed when I click.
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            2. chrij
              yes but if it indicates
              ListBox1.Items.Count = 0 that means there is an issue.

              I have a hard time understanding why..
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            3. nico8002 Author
              Yeah I admit it's weird
              maybe it's because of DT.clear? since it's placed in the remove button function and just before the deletion?
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            4. chrij
              try removing it and see if you have a list with a slightly larger count ;-)
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            5. nico8002 Author
              Yeah, but if I remove it, it gives me the previous error, it highlights the line in yellow and tells me: "It is not possible to modify the element collection when the DataSource property is set."
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          5. chrij
            Hi,
            I've looked into it a bit since yesterday.
            The problem is that you link your data source to your list: you can't modify your list directly (risk of changing the database) and you also can't close your connection (that empties the list).

            We need to find a way to fill your listbox differently so that it uses the data without being tied to the database.
            The solution I posted earlier might be a way to achieve this.
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            1. nico8002 Author
              ah ok I see what you mean
              which solution are you talking about?
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            2. chrij 
              TA.Fill(DT) oleDbConnex.Close() for i=0 to DT.Rows.Count -1 LB_ListeMachines.Items.Add(DT.Rows(i)("NomColonne").toString) Next

              Logically (but is computing a question of logic?? ;-)), this retrieves the data and adds it to the items of the listbox (without binding it)
              It's up to you to tell me if it makes a difference.
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            3. nico8002 Author
              This code, I need to put it in my fill button, right?
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            4. chrij
              yes
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            5. nico8002 Author
              ok ok
              well, I'm going to try this ;)
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          6. nico8002 Author
            Here is the code for the next person who will be in the same situation as me Lol

            The code for the function that fills the listbox

            Private Sub CKB_ChoixToutesMachines_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles
            DT.Clear()
            Dim oleDbConnex As New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data source=C:\..\BDD.mdb")
            Dim oleCmd As New OleDb.OleDbCommand("SELECT NomMachine FROM Machine ORDER BY NomMachine", oleDbConnex)
            Try
            Dim TA As New OleDb.OleDbDataAdapter(oleCmd)
            LB_ListeMachines.Items.Clear()
            TA.Fill(DT)
            oleDbConnex.Close()
            For i = 0 To DT.Rows.Count - 1
            LB_ListeMachines.Items.Add(DT.Rows(i)("NomMachine").ToString)
            Next
            Catch ex As Exception
            MessageBox.Show("Unable to establish a connection to the database!!" & ex.Message)
            End Try
            For i = 0 To LB_ListeMachines.Items.Count - 1
            LB_ListeMachines.SetSelected(i, False)
            Next
            End Sub

            The code for the function to remove an item from the listbox

            Private Sub B_Retirer_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles B_Retirer.Click
            DT.Clear()
            For i = LB_ListeMachines.Items.Count - 1 To 0 Step -1
            If LB_ListeMachines.GetSelected(i) Then
            LB_ListeMachines.Items.RemoveAt(i)
            i = i - 1
            End If
            Next i
            End Sub
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