Using mvc-mini-profiler

问题:

I'm trying to use the mvc-mini-profiler with EFCodeFirst I'm creating a DbProfiledConnection and passing it to the DbContext on construction as below. The application continues to work as expected by the sql is not exposed to the Profiler.

public class WebContext : DbContext
{
    static DbConnection _connection = new SqlConnection(ConfigurationManager.ConnectionStrings["WebContext"].ConnectionString);
    static DbConnection _profiledConnection = MvcMiniProfiler.Data.ProfiledDbConnection.Get(_connection);        

    public WebContext()
            : base(_profiledConnection, true)
    {   

    }

oops my bad.

I've modified it so that when my WebContext is constructed in my UnitOfWork i pass in a ProfiledDbConnection

public UnitOfWork()
{             
    var profiledConnection = MvcMiniProfiler.Data.ProfiledDbConnection.Get(connection);
    this.context = new MyContext(profiledConnection);
}

I've checked and MiniProfier Current has been set in Application_BeginRequest and it returns a ProfiledDbConnection when I then try and query the database an error is thrown in the ProfiledDbProviderServices class.

 protected override string GetDbProviderManifestToken(DbConnection connection)
 {
     return tail.GetProviderManifestToken(connection);
 }

this method returns a "The provider did not return a ProviderManifestToken string." error

回答1:

I suspect this relates to the static field initializer. Connections on web apps should never be static anyway (but request-specific at most).

The key is: what does ProfiledDbConnection actually come out as? The Get method returns a ProfiledDbConnection only if you are currently profiling (on the current request), and the connection is profiled against the MiniProfiler instance on that request.

If you use a static field, then there are two scenarios:

• the static field is initialized without a request context (or a non-developer request context): no profiling will occur as MiniProfiler.Current is null
• the static field is initialized, but everything is logged against the very first request, which is quickly dead