Errors using Pomelo MySQL EF provider with ASP.NET Core 2.0 Preview

Question

I am using Pomelo 1.1.2 on ASP.NET Core 2.0 Preview, along with EF 2.0 Preview. With their demo code, I get the following exception every time I call "UseMySql":

System.TypeLoadException occurred
  HResult=0x80131522
  Message=Method 'Clone' in type 'Microsoft.EntityFrameworkCore.Internal.MySqlOptionsExtension' from assembly 'Pomelo.EntityFrameworkCore.MySql, Version=1.1.1.0, Culture=neutral, PublicKeyToken=null' does not have an implementation.
  Source=<Cannot evaluate the exception source>
  StackTrace:
   at Microsoft.EntityFrameworkCore.MySqlDbContextOptionsExtensions.UseMySql(DbContextOptionsBuilder optionsBuilder, String connectionString, Action`1 mySqlOptionsAction)
   at CoreTest1.Startup.<ConfigureServices>b__4_0(DbContextOptionsBuilder options) in C:\DEV\Experiments\CoreTest1\CoreTest1\Startup.cs:line 27
   at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.<>c__DisplayClass0_0`1.<AddDbContext>b__0(IServiceProvider p, DbContextOptionsBuilder b)
   at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.DbContextOptionsFactory[TContext](IServiceProvider applicationServiceProvider, Action`2 optionsAction)
   at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.<>c__DisplayClass5_0`1.<AddCoreServices>b__0(IServiceProvider p)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactoryService(FactoryService factoryService, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitSingleton(SingletonCallSite singletonCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.<>c__DisplayClass17_0.<RealizeService>b__0(ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider provider)
   at CoreTest1.Controllers.HomeController.Index() in C:\DEV\Experiments\CoreTest1\CoreTest1\Controllers\HomeController.cs:line 18
   at Microsoft.AspNetCore.Mvc.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeActionMethodAsync>d__18.MoveNext()

Wondering if this is just because of the 2.0 preview libraries? Any ideas? I tried to look through their source code on Git to see if I could spot anything immediately wrong, but could not.

Colpitis

2.0 is a major release, major releases generally have breaking changes in API. So don't expect an provider which was written von EF Core 1.1 to work on 2.x. Common sense ;) – Halda

Normally I'd agree, but 2.0 was recently renamed from 1.2 in order to highlight that it's compatible with .NET Standard 2.0. I'm not so sure there's much that's breaking, 2.0 here is more of a marketing title. – Colpitis

Answer 1

Let's look at EF Core 2.0 Preview 1 announcement:

If you are using a third party database provider, then check to see if they have released an update that depends on 2.0.0-preview1-final. If they have, then just upgrade to the new version. If not, then you will not be able to upgrade since version 2.0 contains several breaking changes and 1.* providers are not expected to work with it.

That means Pomelo isn't expected to support EF Core 2.0 until a comparatible release is produced.

Appendage

Answer 2

Recently, faced the same error during my project update to .NET Core 2.0. At this moment, solution is described in https://github.com/PomeloFoundation/Pomelo.EntityFrameworkCore.MySql Basically, update package to the prereleased version 2.0.0-rc-*

<PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="2.0.0-rc-*" />

Consequential

The one that I found that was available was <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="2.0.0-rtm-10062" /> and this solved this issue for me. – Expecting

Answer 3

If you are using asp.net core 2.0, you need to use pomelo 2.0.0. Asp.net core 2.0 does not work with pomelo 2.1 or higher.

Boil

please clarify how this is an answer to the OP's question. see How to Answer for details about how to provide a good answer. – Mayers

also what does "On the console I have syntax errors in database" mean? – Mayers