Cannot resolve scoped service 'xxDbContext' from root provider for version v2.6

[ShenZZ]

执行dbContext.Database.BeginTransaction(_capBus)会抛异常 : Cannot resolve scoped service 'xxDbContext' from root provider

开发环境:

<PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="DotNetCore.CAP.RabbitMQ" Version="2.6.0" />
    <PackageReference Include="DotNetCore.CAP.SqlServer" Version="2.6.0" />
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.2.6" />
  </ItemGroup>

数据库: sqlserver localdb 2016

经测试DotNetCore.CAP.SqlServer 2.5.1可以通过 而2.6.0会报错 100%重现

错误堆栈:

fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
An unhandled exception has occurred while executing the request.
System.InvalidOperationException: Cannot resolve scoped service 'Sample.RabbitMQ.SqlServer.AppDbContext' from root provider.
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteValidator.ValidateResolution(Type serviceType, IServiceScope scope, IServiceScope rootScope)
at Microsoft.Extensions.DependencyInjection.ServiceProvider.Microsoft.Extensions.DependencyInjection.ServiceLookup.IServiceProviderEngineCallback.OnResolve(Type serviceType, IServiceScope scope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
at DotNetCore.CAP.SqlServerCapTransaction..ctor(IDispatcher dispatcher, IServiceProvider serviceProvider) in C:\projects\src\DotNetCore.CAP.SqlServer\ICapTransaction.SqlServer.cs:line 27
--- End of stack trace from previous location where exception was thrown ---

[yang-xiaodong]

It looks like a bug, I will fix it later, thanks for your report

[yang-xiaodong]

Hello, I am testing works normally, and can't reproduce your issue.

[yang-xiaodong]

The extension method BeginTransaction are not inject the DbContext service

        public static IDbContextTransaction BeginTransaction(this DatabaseFacade database,
            ICapPublisher publisher, bool autoCommit = false)
        {
            var trans = database.BeginTransaction();
            publisher.Transaction.Value = publisher.ServiceProvider.GetService<CapTransactionBase>();
            var capTrans = publisher.Transaction.Value.Begin(trans, autoCommit);
            return new CapEFDbTransaction(capTrans);
        }

[ShenZZ]

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="DotNetCore.CAP.RabbitMQ" Version="2.6.0" />
    <PackageReference Include="DotNetCore.CAP.SqlServer" Version="2.6.0" />
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.2.6" />
  </ItemGroup>
</Project>

public class Person
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }
    public class AppDbContext : DbContext
    {
        public AppDbContext(DbContextOptions option) : base(option) { }
        public DbSet<Person> Persons { get; set; }
    }

public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }
        public IConfiguration Configuration { get; }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<AppDbContext>(options =>
                options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

            services.AddCap(x =>
            {
                x.UseEntityFramework<AppDbContext>();
                x.UseRabbitMQ(option => {
                    option.ConnectionFactoryOptions = action =>
                    {
                        Configuration.GetSection("rabbit").Bind(action);
                        action.AuthMechanisms = new List<AuthMechanismFactory>() { new AliyunMechanismFactory() };
                    };
                });
            });

            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
        }
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            app.UseMvc();
        }
    }

[Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        private readonly ICapPublisher _capBus;
        public ValuesController(ICapPublisher capPublisher)
        {
            _capBus = capPublisher;
        }

        [Route("~/ef/transaction")]
        public IActionResult EntityFrameworkWithTransaction([FromServices]AppDbContext dbContext)
        {
            using (
                var trans = dbContext.Database.BeginTransaction(_capBus, autoCommit: false))
            {
                dbContext.Persons.Add(new Person() { Name = "ef.transaction" });
                _capBus.Publish("sample.rabbitmq.mysql", DateTime.Now);
                dbContext.SaveChanges();
                trans.Commit();
            }
            return Ok();
        }
    }

[hmoratopcs]

@yang-xiaodong Hi, I have the same problem. I have added a new sample to my fork (https://github.com/hmoratopcs/CAP/tree/master/samples/Sample.RabbitMQ.SqlServer). I'll be glad to make a pull request if you want to merge it.

I get the following exception when browsing to http://localhost:38447/adonet/transaction or http://localhost:38447/ef/transaction:

System.InvalidOperationException
  HResult=0x80131509
  Message=Cannot resolve scoped service 'Sample.RabbitMQ.SqlServer.AppDbContext' from root provider.
  Source=Microsoft.Extensions.DependencyInjection
  StackTrace:
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteValidator.ValidateResolution(Type serviceType, IServiceScope scope, IServiceScope rootScope)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.Microsoft.Extensions.DependencyInjection.ServiceLookup.IServiceProviderEngineCallback.OnResolve(Type serviceType, IServiceScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at DotNetCore.CAP.SqlServerCapTransaction..ctor(IDispatcher dispatcher, IServiceProvider serviceProvider) in ~\src\DotNetCore.CAP.SqlServer\ICapTransaction.SqlServer.cs:line 32
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() in E:\A\_work\482\s\src\mscorlib\src\System\Runtime\ExceptionServices\ExceptionDispatchInfo.cs:line 132

A related question: Why is _dbContext?.SaveChanges(); called at the Commit method of SqlServerCapTransaction but not at MySqlCapTransaction and PostgreSqlCapTransaction?

[hmoratopcs]

Hi @yang-xiaodong, thanks for reopening the issue.

If I remove the line

_dbContext = serviceProvider.GetService(sqlServerOptions.DbContextType) as DbContext;

from SqlServerCapTransaction it works fine for me. However, without that line, the

_dbContext?.SaveChanges();

which was added on purpose in the following commit loses its effect:

committed on 25 Aug 2018 08ac461#diff-9ce48cd162f0ebe3149fab1677e50fd5R30
add save change when transaction commit

Do you remember why the SaveChanges was needed? Do you think it's safe for me to remove both lines and make a pull request?

[yang-xiaodong]

@hmoratopcs
Hello, thank you for your continued follow-up on this issue. I have recently focused on the version 3.0 features.
Is this exception only when using EF ?

[hmoratopcs]

I've tried to use UseSqlServer instead of UseEntityFramework at Startup.cs and it works, thanks.