C#•3d ago

✅ Random error only when app is run on same server as database

I made a simple dotnet application that uses a remote database When I run it on my local computer it works flawlessly, I dont see the error and the application works When I run it on the same server as the database half of the time I get errors half the time it works correctly with no error I was told the connection needs to be closed but I dont think I did that correctly as I still get the same errors The errors I get are This method may not be called when another read operation is pending. or Connection must be valid and open. or Object reference not set to an instance of an object. This is most common, the save does appear to work as the database gets updated but the app shows this error This is the database class

namespace DataLibrary
{
    public class DataAccess : IDataAccess
    {
        public async Task<List<T>> LoadData<T, U>(string sql, U parameters, string connectionString)
        {
            using (IDbConnection connect = new MySqlConnection(connectionString))
            {
                var rows = await connect.QueryAsync<T>(sql, parameters);
                connect.Close();
                return rows.ToList();
            }
        }
        public Task SaveData<T>(string sql, T parameters, string connectionString)
        {
            using (IDbConnection connect = new MySqlConnection(connectionString))
            {
                var value = connect.ExecuteAsync(sql, parameters);
                connect.Close();
                return value;

            }
        }
    }
}

namespace DataLibrary
{
    public class DataAccess : IDataAccess
    {
        public async Task<List<T>> LoadData<T, U>(string sql, U parameters, string connectionString)
        {
            using (IDbConnection connect = new MySqlConnection(connectionString))
            {
                var rows = await connect.QueryAsync<T>(sql, parameters);
                connect.Close();
                return rows.ToList();
            }
        }
        public Task SaveData<T>(string sql, T parameters, string connectionString)
        {
            using (IDbConnection connect = new MySqlConnection(connectionString))
            {
                var value = connect.ExecuteAsync(sql, parameters);
                connect.Close();
                return value;

            }
        }
    }
}

15 Replies

WastedOP•3d ago

I tried adding a 100mS delay but still get a random error Object reference not set to an instance of an object. And is still works correctly on my local computer with the remote database

ǝǝʞǝǝʞ•2d ago

What is the type of the rows variable? Also not awaiting the ExecuteAsync

WastedOP•2d ago

My c# skills are not that good I couldn't work out how to remove await What do youmean by type of rows available? I've used it on different tables with different data and it works always when on a different computer from the database, but half time when on the same server as the database

ǝǝʞǝǝʞ•20h ago

public Task SaveData<T>(string sql, T parameters, string connectionString)

public Task SaveData<T>(string sql, T parameters, string connectionString)

public async Task SaveData<T>(string sql, T parameters, string connectionString)

public async Task SaveData<T>(string sql, T parameters, string connectionString)

var value = connect.ExecuteAsync(sql, parameters);

var value = connect.ExecuteAsync(sql, parameters);

var value = await connect.ExecuteAsync(sql, parameters);

var value = await connect.ExecuteAsync(sql, parameters);

Not awaiting the connect.ExecuteAsync(sql, parameters) will just let it keep going and close the connection.

WastedOP•20h ago

II get this error for the return value; Cannot implicitly convert type 'int' to 'System.Threading.Tasks.Task'

ǝǝʞǝǝʞ•20h ago

Change the return type to Task<int> if you want the affected row counts back Then further up the call stack you have to await SaveData()

WastedOP•19h ago

seems to work now what happens if I dont await SaveData?

ǝǝʞǝǝʞ•19h ago

Why would you not want to await? If you just want to fire and forget then it will probably crash the app with an UnobservedTaskException if SaveData throws any exceptions and you don't prevent them from bubbling up.

WastedOP•19h ago

Do i need to explicitly close the connection?

ǝǝʞǝǝʞ•19h ago

Depends on what IDisposable does for a MySqlConnection Looks like on dispose it will close it for you

WastedOP•19h ago

OK thanx, I'll just leave the dispose. What do I do with this thread when the issue is solved?

ǝǝʞǝǝʞ•19h ago

!close

Accord•19h ago

Ask the thread owner or member with permission to close this!

WastedOP•19h ago

!close

Accord•19h ago

Closed!

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✅ Random error only when app is run on same server as database