Using the "per-request" approach with StructureMap and IDbConnection - the connection is opened but is closed when executed

Question

Using the "per-request" approach with StructureMap and IDbConnection - the connection is opened but is closed when executed

dapper structuremap

Question

Trying to set up Dapper with StructureMap to utilize a "per request" type of scenario. In my Global.asax I have the following (modified from an old post of Ayende's involving NHibernate, and one I found discussing the BuildUp() method in StructureMap):

protected static IDbConnection CreateConnection() { 
    var settings = ConfigurationManager.ConnectionStrings["MyConnectionString"];
    var connection = DbProviderFactories.GetFactory(settings.ProviderName).CreateConnection();
    if (connection == null) { 
        throw new ArgumentNullException("connection");
    }
    connection.ConnectionString = settings.ConnectionString;
    return connection;
}

public static IDbConnection CurrentConnection { 
    get { return (IDbConnection)HttpContext.Current.Items["current.connection"]; }
    set { HttpContext.Current.Items["current.connection"] = value; }
}

public Global() { 
    BeginRequest += (sender, args) => { 
        CurrentConnection = CreateConnection();
        CurrentConnection.Open(); 
    };

    EndRequest += (sender, args) => { 
        if (CurrentConnection == null) return;
        CurrentConnection.Close();
        CurrentConnection.Dispose();
    }
}

void Application_Start(object sender, EventArgs e) { 
    ObjectFactory.Initialize(x => { 
        x.For<IDbConnection>().Singleton().Use(CreateConnection());
        x.For<ICustomerRepository>().Use<CustomerRepository>();
        x.SetAllProperties(y => y.OfType<ICustomerRepository>());
    });
}

// BasePage.cs
public class BasePage : System.Web.UI.Page { 
    public IDbConnection CurrentConnection { get; set; }

    public BasePage() { 
        ObjectFactory.BuildUp(this);
    }
}

Every time I try to call this, the actual query fails with an error stating the Connection's current state is closed, although a breakpoint on the BeginRequest handler shows that Open() is being called on the connection.

It seems to work if I manually call Open and Close on the IDbConnection inside each repository method, but I'm trying to avoid having to do that if at all possible.

Wayne Molina

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PHeiberg · Accepted Answer · 5/29/2012 5:08:23 AM

You're creating the connection as a singleton. That means that there will only be one connection object used for the entire applications pages. The connection that you new up in the Application_Start handler is never used by the pages, since they will get the connection from the container.

You would be better off using something like this:

void Application_Start(object sender, EventArgs e) { 
    ObjectFactory.Initialize(x => { 
        x.For<IDbConnection>().HttpContextScoped().Use(() => CreateConnection());
        ...
    }
}

 public Global() { 
    EndRequest += (sender, args) => { 
        ObjectFactory.GetInstance<IDbConnection>.Dispose();
    }
 }

Using the "per-request" approach with StructureMap and IDbConnection - the connection is opened but is closed when executed

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