BackgroundWork does not get value of ComboBox?

Question

I have a ComboBox of objects and I do insert these values into my database, it work. Now I'm trying create a BackgroundWorker to insert and to control components of Form, for example buttons and progress and ComboBox itself. The problem is that after BackgroundWorker is added I can't get value selected in ComboBox and I can't understand what is this problem.

How could I solve it ?

Method to insert

/** insere Perfil + Modulo */
        private void insertPerfilModulo() {            
            Perfil perfil = (Perfil)cbxPerfilModulo.SelectedItem;
            IList<Modulo> lista = getListaModulo();

            foreach(Modulo m in lista){                
                Permissao permissao = new Permissao();
                permissao.perfil = perfil;
                permissao.modulo = m;

                Boolean exist = dao.isExistPerfilAndModulo(permissao);                
                if (exist) {
                    Permissao p = dao.getPermissao(permissao);                    
                    dao.update(p);
                }else {
                    dao.insert(permissao);
                }
            }
        }

Button to start BackgroundWorker

private void btnSalvarPM_Click(object sender, EventArgs e) {    
    if (!backgroundWorker1.IsBusy) {
        progressBar1.Visible = true;                
        cbxPerfilModulo.Enabled = false;
        btnSalvarPM.Enabled = false;
        backgroundWorker1.RunWorkerAsync();
    }            
}

DoWork

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) {
            insertPerfilModulo();
        }

Exception

The thread '<No Name>' (0x1870) has exited with code 0 (0x0).
'PubControl.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Numerics\v4.0_4.0.0.0__b77a5c561934e089\System.Numerics.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll
The program '[5396] PubControl.vshost.exe: Program Trace' has exited with code 0 (0x0).
The program '[5396] PubControl.vshost.exe: Managed (v4.0.30319)' has exited with code -1 (0xffffffff).

ChrisF · Accepted Answer · 2016-03-11T22:35:20.980

3

You are trying to access the UI thread from the background worker. That's not allowed.

You'll need to pass the background worker all the information it needs to do it's business - in this case the selected item from the combo box.

In this case you'll have something like this:

  backgroundWorker1.RunWorkerAsync(cbxPerfilModulo.SelectedItem);

Then in the worker:

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    Perfil perfil = (Perfil)e.Argument;
    insertPerfilModulo(perfil);
}

Where you will need to change your method to accept an argument of the item being processed.

edited Mar 11 '16 at 22:35

answered Mar 11 '16 at 22:17

ChrisF

134,786
31
255
325

How could I do this ? Do you have an example ? – FernandoPaiva Mar 11 '16 at 22:20
1

@FernandoPaiva Just read the documentation [BackgroundWorker.RunWorkerAsync Method (Object)](https://msdn.microsoft.com/en-us/library/f00zz5b2(v=vs.110).aspx) – Ivan Stoev Mar 11 '16 at 22:23
1

Example here: http://stackoverflow.com/questions/1862590/how-to-update-gui-with-backgroundworker – ManoDestra Mar 11 '16 at 22:43

BackgroundWork does not get value of ComboBox?

1 Answers1