Using mini-profiler and MVC3 - profiling connections from model class in separate dll

Question

I've got an MVC3 project and one of the models is built as a separate class library project, for re-use in other applications.

I'm using mini-profiler and would like to find a way to profile the database connections and queries that are made from this class library and return the results to the MVC3 applciation.

Currently, in my MVC3 app, the existing models grab a connection using the following helper class:

public class SqlConnectionHelper
{
    public static DbConnection GetConnection()
    {
        var dbconn = new SqlConnection(ConfigurationManager.ConnectionStrings["db"].ToString());
        return new StackExchange.Profiling.Data.ProfiledDbConnection(dbconn, MiniProfiler.Current);
    }
}

The external model can't call this function though, because it knows nothing of the MVC3 application, or of mini-profiler.

One way I thought of would be to have an IDbConnection Connection field on the external model and then pass in a ProfiledDbConnection object to this field before I call any of the model's methods. The model would then use whatever's in this field for database connections, and I should get some profiled results in the MVC3 frontend.

However, I'm not sure if this would work, or whether it's the best way of doing this. Is there a better way I'm missing?

Answer 1

ProfiledDbConnection isn't dapper: it is mini-profiler. We don't provide any magic that can take over all connection creation; the only thing I can suggest is to maybe expose an event in your library that can be subscribed externally - so the creation code in the library might look a bit like:

public static event SomeEventType ConnectionCreated;
static DbConnection CreateConnection() {
    var conn = ExistingDbCreationCode();
    var hadler = ConnectionCreated;
    if(handler != null) {
        var args = new SomeEventArgsType { Connection = conn };
        handler(typeof(YourType), args);
        conn = args.Connection;
    }
    return conn;
}

which could give external code the chance to do whatever they want, for example:

YourType.ConnectionCreated += (s,a) => {
    a.Connection = new StackExchange.Profiling.Data.ProfiledDbConnection(
        a.Connection, MiniProfiler.Current);
};