Winform - changing a method to async/await

问题

I have a winform with six listbox side-by-side. Under each listbox there is a textbox and a Button labeled "Add." When you put something in the textboxand press the Add button, using EF, I update a table for that listbox and I re-dataBind the listbox. Here's a sample of one of the event handlers for Add button:

private void btnOfferType_Click(object sender, EventArgs e)
{
    TypeCategoryAdd("OfferType", tbOfferType.Text.Trim());
}

TypeCategoryAdd function is listed below. I want to do this (notice the await):

private async void btnOfferType_Click(object sender, EventArgs e)
{
    await TypeCategoryAdd("OfferType", tbOfferType.Text.Trim());
}

What do I need to do in order make the TypeCategoryAdd function to run on different context so that the winform UI don't freeze up when DB update is happening?

private void TypeCategoryAdd (string table, string item)
{
    if (string.IsNullOrEmpty(item)) return;

    using (MenuGenerator.NewArchMenuGeneratorEntities con = new NewArchMenuGeneratorEntities())
    {
        switch (table)
        {
            case "OfferType":
                if (con.OfferTypes.Any(x=>x.Name == item))
                {
                    MessageBox.Show("There is already a " + item + " on the list!");
                    tbOfferType.Text = "";
                    return;
                }
                OfferType ot = new OfferType();
                ot.Name = item;
                con.OfferTypes.Add(ot);
                try
                {
                    con.SaveChanges();
                    tbOfferType.Text = "";
                    lstOfferType.DataSource = con.OfferTypes.OrderBy(x=>x.Id).ToList();                    
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Error " + ex.ToString());
                }
                break;                

            }
            return;
        }

回答1:

What you should do it to take advantage of the async methods in EF 6:

private async Task TypeCategoryAdd (string table, string item)
{
    if (string.IsNullOrEmpty(item)) return;

    using (MenuGenerator.NewArchMenuGeneratorEntities con = new NewArchMenuGeneratorEntities())
    {
        switch (table)
        {
            case "OfferType":
                if (await con.OfferTypes.AnyAsync(x=>x.Name == item))
                {
                    MessageBox.Show("There is already a " + item + " on the list!");
                    tbOfferType.Text = "";
                    return;
                }
                OfferType ot = new OfferType();
                ot.Name = item;
                con.OfferTypes.Add(ot);
                try
                {
                    await con.SaveChangesAsync();
                    tbOfferType.Text = "";
                    lstOfferType.DataSource = await con.OfferTypes.OrderBy(x=>x.Id).ToListAsync();
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Error " + ex.ToString());
                }
                break;                

            }
            return;
        }
    }
}

回答2:

You can wrap your database access in a Task, and await on that.

private async void btnOfferType_Click(object sender, EventArgs e)
{
    await Task.Run(()=>TypeCategoryAdd("OfferType", tbOfferType.Text.Trim()));
}

来源：https://stackoverflow.com/questions/37402108/winform-changing-a-method-to-async-await

标签

multithreading

winforms

async-await