using async / await to fill DGV

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Hi I am have a litle problems firing my datagridview using the async / await method.

Button click event:

C#

private async void button2_Click(object sender, EventArgs e)
        {
            datagridview1.Visible = true;
            //Progressbar  
            Progressbar1  .Visible = true;
            Progressbar1  .Style = ProgressBarStyle.Marquee;
            var period2 = cb1.SelectedValue.ToString();
            var period1 = cb2.SelectedValue.ToString();
           

            /*A variable to hold the parameters*/
            //var table = await loadTable((period1, period2));

            await Task.Run(() => loadTable(period1, period2));

             /*back to the UI */
            //datagridview1.DataSource = datatable;
            
            //datagridview1.DataSource = table;

            Progressbar1  .Visible = false;
        }

I haved tried fetching the DGV by using the using the two // datagridview.DataSource line without success.

My Task method:

C#

 private async Task Zugänge(string period1, string period2) 

{

    //
    string C = ConfigurationManager.ConnectionStrings["123"].ConnectionString;
    using (var con = new SqlConnection(C))
    using (var cmd = new SqlCommand())
    {
        cmd.Connection = con;
        cmd.CommandText = ("[dbo].[spInfo]");
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Parameters.AddWithValue("@Periode2", period2);
        cmd.Parameters.AddWithValue("@Periode1", period1);
        // open the connection
        con.Open();
        SqlDataAdapter adapter = new SqlDataAdapter(cmd);
        DataTable datatable = new DataTable();
        adapter.Fill(datatable );
       
        await Task.Run(() => adapter.Fill(datatable ));
        
    }
}

Posted 16-Jun-15 22:04pm

mikybrain1

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Comments

Afzaal Ahmad Zeeshan 17-Jun-15 4:19am

What is the failure report? Can you share why you believe this code isn't working?

Also remember, async/await operators just allow you to use the Asynchronous programming model in your application. Otherwise, they are of no use to work with graphics.

mikybrain1 17-Jun-15 4:36am

Ok. If i use the line var table = await loadTable((period1, period2)); and set it to the DGV it underline table saying "void" can not implicitly typed local variables are allocated.

And if I use this line: datagridview1.DataSource = datatable; it states the name database does not exist in the current context.

Afzaal Ahmad Zeeshan 17-Jun-15 4:40am

It would state, datatable does not exist in the current context, there is no identifier database being used here.

Also, void cannot be saved to a variable value. loadTable might be returning a void (signature might be, private async void loadTable), thus it does not allow you.

mikybrain1 17-Jun-15 4:54am

Thnx to CHill60 who make me think further even when I#m desperated.

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mikybrain1 · Accepted Answer · 2015-06-16T22:51:00

I added a return to end of my Task method:

private async Task Zugänge(string period1, string period2) 
 
{
 
    //
    string C = ConfigurationManager.ConnectionStrings["123"].ConnectionString;
    using (var con = new SqlConnection(C))
    using (var cmd = new SqlCommand())
    {
        cmd.Connection = con;
        cmd.CommandText = ("[dbo].[spInfo]");
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Parameters.AddWithValue("@Periode2", period2);
        cmd.Parameters.AddWithValue("@Periode1", period1);
        // open the connection
 // Here open the connection async:
        await con.OpenAsync();
        SqlDataAdapter adapter = new SqlDataAdapter(cmd);
        DataTable datatable = new DataTable();
        adapter.Fill(datatable );
       
        await Task.Run(() => adapter.Fill(datatable ));
return dt;
        
    }
}