MediatR.cs

public TResult Send<TResult>(IRequest<TResult> message)
{
    var context = Container.GetInstance<MyContext>();
    var mediator = Container.GetInstance<IMediator>();
    DbContextTransaction txn = null;
    TResult result;

    try
    {
        txn = context.Database.BeginTransaction();
        result = mediator.Send(message);
        txn.Commit();
    }
    catch (Exception)
    {
        txn?.Rollback();
        throw;
    }

    return result;
}