For usage in my current project I've created a class that allows me to call SQL Server async.
My code looks like this:
internal class CommandAndCallback<TCallback, TError>
{
public SqlCommand Sql { get; set; }
public TCallback Callback { get; set; }
public TError Error { get; set; }
}
class MyCodes:SingletonBase<MyCodes>
{
private static string _connString = @"Data Source=MyDB;Initial Catalog=ED;Integrated Security=True;Asynchronous Processing=true;Connection Timeout=0;Application Name=TEST";
private MyCodes() { }
public void SetSystem(bool production)
{
_connString =
string.Format(@"Data Source=MyDB;Initial Catalog={0};Integrated Security=True;Asynchronous Processing=true;Connection Timeout=0;Application Name=TEST", production ? "ED" : "TEST_ED");
}
public void Add(string newCode, Action<int> callback, Action<string> error)
{
var conn = new SqlConnection(_connString);
SqlCommand cmd = conn.CreateCommand();
cmd.CommandTimeout = 0;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = @"ADD_CODE";
cmd.Parameters.Add("@NEW", SqlDbType.NVarChar).Value = newCode;
cmd.Parameters.Add("@NewId", SqlDbType.Int).Direction = ParameterDirection.Output;
try
{
cmd.Connection.Open();
}
catch (Exception ex)
{
error(ex.ToString());
return;
}
var ar = new CommandAndCallback<Action<int>, Action<string>> { Callback = callback, Error = error, Sql = cmd };
cmd.BeginExecuteReader(Add_Handler, ar, CommandBehavior.CloseConnection);
}
private static void Add_Handler(IAsyncResult result)
{
var ar = (CommandAndCallback<Action<int>, Action<string>>)result.AsyncState;
if (result.IsCompleted)
{
try
{
ar.Sql.EndExecuteReader(result);
ar.Callback(Convert.ToInt32(ar.Sql.Parameters["@NewId"].Value));
}
catch (Exception ex)
{
ar.Error(ex.Message);
}
}
else
{
ar.Error("Error executing SQL");
}
}
public void Update(int codeId, string newCode, Action callback, Action<string> error)
{
var conn = new SqlConnection(_connString);
SqlCommand cmd = conn.CreateCommand();
cmd.CommandTimeout = 0;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = @"UPDATE_CODE";
cmd.Parameters.Add("@CODE_ID", SqlDbType.Int).Value = codeId;
cmd.Parameters.Add("@NEW", SqlDbType.NVarChar).Value = newCode;
try
{
cmd.Connection.Open();
}
catch (Exception ex)
{
error(ex.ToString());
return;
}
var ar = new CommandAndCallback<Action, Action<string>> { Callback = callback, Error = error, Sql = cmd };
cmd.BeginExecuteReader(Update_Handler, ar, CommandBehavior.CloseConnection);
}
private static void Update_Handler(IAsyncResult result)
{
var ar = (CommandAndCallback<Action, Action<string>>)result.AsyncState;
if (result.IsCompleted)
{
try
{
ar.Sql.EndExecuteReader(result);
ar.Callback();
}
catch (Exception ex)
{
ar.Error(ex.Message);
}
}
else
{
ar.Error("Error executing SQL");
}
}
}
This may look like too much of code, but it lets me call it as so:
private void Add_Click(object sender, EventArgs e)
{
MyCodes.Instance.Add("Test",Success,Error)
}
private void Success(int newId)
{
MessageBox.Show(newId.ToString(), "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
private void Error(string error)
{
MessageBox.Show(error, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
Above code works just fine for me, I'm able to do every call async.
Problem that I have right now is to do multiple calls as transaction - I would like to update 2 codes and add one new.
Normally I would call update, then in success handler call second update, and in handler to second update I would call add that would return new id.
Something like:
-UPDATE CODE
|-UPDATE CODE
|-ADD CODE (only this one return something)
But I would like to call all of those as transaction, so if add code would break updates would rollback.
Question:
Is it possible to call multiple async queries as a transaction?
Can I call my above methods as transaction or do I must create separate method to call my procedures as one? (I would like to avoid this one because it's just copying the same code from one method to another)
I would like to add that I use .NET 3.5 so await and other nice features aren't an option.
Yes, it is possible. Simply call
SqlConnection.BeginTransaction
before your first call, make you assign the returnedSqlTransaction
object to eachSqlCommand.Transaction
in the chain and callSqlTransaction.Commit()
at the end.