How do I handle Database Connections with Dapper in .NET?

Question

I\'ve been playing with Dapper, but I\'m not sure of the best way to handle the database connection.

Most examples show the connection object being created in the

Answer 1

Everyone appears to be opening their connections entirely too early? I had this same question, and after digging through the Source here - https://github.com/StackExchange/dapper-dot-net/blob/master/Dapper/SqlMapper.cs

You will find that every interaction with the database checks the connection to see if it is closed, and opens it as necessary. Due to this, we simply utilize using statements like above without the conn.open(). This way the connection is opened as close to the interaction as possible. If you notice, it also immediately closes the connection. This will also be quicker than it closing automatically during disposal.

One of the many examples of this from the repo above:

    private static int ExecuteCommand(IDbConnection cnn, ref CommandDefinition command, Action paramReader)
    {
        IDbCommand cmd = null;
        bool wasClosed = cnn.State == ConnectionState.Closed;
        try
        {
            cmd = command.SetupCommand(cnn, paramReader);
            if (wasClosed) cnn.Open();
            int result = cmd.ExecuteNonQuery();
            command.OnCompleted();
            return result;
        }
        finally
        {
            if (wasClosed) cnn.Close();
            cmd?.Dispose();
        }
    }

Below is a small example of how we use a Wrapper for Dapper called the DapperWrapper. This allows us to wrap all of the Dapper and Simple Crud methods to manage connections, provide security, logging, etc.

  public class DapperWrapper : IDapperWrapper
  {
    public IEnumerable Query(string query, object param = null, IDbTransaction transaction = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null)
    {
      using (var conn = Db.NewConnection())
      {
          var results = conn.Query(query, param, transaction, buffered, commandTimeout, commandType);
          // Do whatever you want with the results here
          // Such as Security, Logging, Etc.
          return results;
      }
    }
  }