Populating a datagrid using backgroung worker: multithreading, back ground

Populating a datagrid using backgroung worker

Im trying to bind a grid to a datasource using the backgroundworker. After a lot of research and help from some experts on EE I got to a point where i think im successfully populating the dataset with records but the grid is not populating.

On my form I have a search() function that returns a sql query string which is passed to the background worker. PLease see code below

at the RunWorkerCompleted event the grid is not being populated. I feel like im really close to the solution .just some small thing im missing out somewhere.

Private Sub SimpleButton2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SimpleButton2.Click
        Dim sql = search()
         BGW = New BackgroundWorker
        BGW.WorkerReportsProgress = True
        BGW.WorkerSupportsCancellation = True
        BGW.RunWorkerAsync(sql)
 
        SimpleButton2.Enabled = False
END SUB
 
 Private Sub BGW_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BGW.DoWork
        Dim sql As String = String.Empty
        TextBox2.Text = sql
        If e.Argument IsNot Nothing Then
            sql = DirectCast(e.Argument, String)
        Else
            'Add code if your sql string is nothing
        End If
 
        'now delare your dataset and dataadapter and your connection
        'just as you did earlier only now they are delared inside the worker thread...
        Dim ds As New DataSet
        Dim da As New SqlDataAdapter
 
 
        da = New SqlDataAdapter(sql, conns)
        da.SelectCommand.CommandTimeout = 200
        da.Fill(ds, "listings")
 
        'Now the data is in the ds created above, but on a different thread
        'so we need to get this to the Work_Completed...
        e.Result = ds
End Sub
 
 Private Sub BGW_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BGW.RunWorkerCompleted
        If e.Error IsNot Nothing Then
            MsgBox("There was an error ...")
            BGW.Dispose()
            Exit Sub
        End If
 
        If e.Cancelled = False Then
            If e.Result IsNot Nothing Then
                GridControl1.DataSource = ds.Tables("listings")
 
                BGW.Dispose()
                SimpleButton2.Enabled = True
            End If
        Else
            'TODO: add code for cancellation
 
        End If
    End Sub

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Populating a datagrid using backgroung worker

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multithreading

back ground

Microsoft Visual Basic.Net

.NET

Visual Studio

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