如何在Web Api控制器C＃中使用Async / await任务连接数据库并返回值

Question

Hello i am trying to connect with database and return values from a web api controller.I want to do it all the way asynchronous with new task to have better performance if it is possible.here is an example of what i have done.Am i doing it the correct way?Am i using correct the using statements?is the await correct in Open,Close connection and sda.FillAsync ?Thanks!

 public async Task<HttpResponseMessage> Get()
 {
   return await Task.Run(() => GetAllCustomers());
 }

    private async Task <HttpResponseMessage> GetAllCustomers()
    {
        DataTable Customers= new DataTable();

        using (MySqlConnection con = new MySqlConnection(""))
        using (MySqlCommand cmd = new MySqlCommand("SELECT * FROM Customers", con))
        {
            try
            {
                if (con.State == ConnectionState.Closed)
                {
                    await con.OpenAsync();
                    cmd.CommandType = CommandType.Text;
                    MySqlDataAdapter sda = new MySqlDataAdapter(cmd);
                    await sda.FillAsync(Customers);
                }
            }

            catch (MySqlException ex)
            {
                ex.Message.ToString();
            }
            finally
            {
                await con.CloseAsync();
            }
        }
        return ControllerContext.Request
       .CreateResponse(HttpStatusCode.OK, new { Customers });
    }

Answer 1

Replace

return await Task.Run(() => GetAllCustomers());

with

return await GetAllCustomers();

You don't need to run the service task explicitly (the controller method is already marked as async ).

Rename GetAllCustomers to GetAllCustomersAsync (best-practice naming convention)

I prefer to code WebApis this way:

public async Task<IHttpActionResult> Get() 
{
    try 
    {
         var result = await GetAllCustomersAsync();
         return Ok(result);
    }
    catch(Exception ex) 
    {
        return InternalServerError(ex);
    }
}

UPDATE : An update to show how your database-operation can be simplified:

private async Task<Customers> GetAllCustomersAsync()
{
   var customers = new DataTable();
   using (var con = new MySqlConnection(""))
   using (var cmd = new MySqlCommand("SELECT * FROM Customers", con))
   {
       await con.OpenAsync();
       cmd.CommandType = CommandType.Text;
       var sda = new MySqlDataAdapter(cmd);
       await sda.FillAsync(customers);
   }
   return customers;
}