Integrations: Entity Framework Core

[NickCraver]

Originating in #130, need to see how Entity Framework Core works, likely create MiniProfiler.EntityFrameworkCore (or MiniProfiler.Providers.EntityFrameworkCore, depending on the integration) and get a sample in.

• Investigate Entity Framework Core
  • ProfiledDbConnection
  • Events (possible they have profiling hooks already)
• (If needed) Create MiniProfiler.Providers.EntityFrameworkCore package
• Add Entity Framework Core to the ASP.NET Core MVC sample

[NickCraver]

I'm working with the EF team on best approaches here: dotnet/efcore#7939

[NickCraver]

Closing this out, a new package is available for testing: MiniProfiler.EntityFrameworkCore. I welcome issues anyone hits and it'll continue to progress as System.Diagnostics does.

[chadwackerman]

Works great. And "just works" with ASP.NET Identity (specifically Microsoft.AspNetCore.Identity.EntityFrameworkCore) which was always problematic with MVC in the past.

Inside Startup.Configure I had some database access. Initialization isn't fully complete yet (I believe MiniProfiler.Current isn't set) and it throws an exception in RelationalDiagnosticListener.cs/OnBeforeExecuteCommand.

Moving the database calls above app.UseMiniProfiler(...) is a workaround.

[NickCraver]

@chadwackerman Doh, I'm stupid...not sure why I made that throw. Next build will include adbdca2 to fix that bad behavior.

[chadwackerman]

I believe I'm seeing a variation of this on alpha8-165.

Program.cs:

public static async Task Main(string[] args)
{
    var host = BuildWebHost(args);

    using (var scope = host.Services.CreateScope())
    {
        var services = scope.ServiceProvider;
        var db = services.GetRequiredService<ApplicationDbContext>();
        var foo = db.Whatever.FirstOrDefault(); // throws
    }

    host.Run();
}

public static IWebHost BuildWebHost(string[] args)
{
    return WebHost.CreateDefaultBuilder(args)
        .UseKestrel()
        .UseContentRoot(Directory.GetCurrentDirectory())
        .UseIISIntegration()
        .UseStartup<Startup>()
        .Build();
}

If I remove .AddEntityFramework() from the services.AddMiniProfiler() call in Startup.cs, it works.

[NickCraver]

What error does it throw?

[chadwackerman]

System.NullReferenceException: Object reference not set to an instance of an object.
   at StackExchange.Profiling.Data.RelationalDiagnosticListener.OnNext(KeyValuePair 2 kv) in C:\projects\dotnet\src\MiniProfiler.EntityFrameworkCore\RelationalDiagnosticListener.cs:line 114
   at System.Diagnostics.DiagnosticListener.Write(String name, Object value)
   at Microsoft.EntityFrameworkCore.Internal.RelationalLoggerExtensions.ConnectionOpened(IDiagnosticsLogger`1 diagnostics, IRelationalConnection connection, DateTimeOffset startTime, TimeSpan duration, Boolean async)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.<OpenAsync>d__34.MoveNext()

[chadwackerman]

Fixed on alpha9-202

[NickCraver]

Closing this out to clean up :)