how to use multi DBContextPool?

entity-framework-core

Question

In EFCore 2.0 Add new feature, DbContext pooling. i know how to use it in single context, however, sometimes need multi context in project,

public class BContext : DbContext
{
    public BContext(DbContextOptions<BContext> options) : base(options) { }
}

public class AContext : DbContext
{
    public AContext(DbContextOptions<AContext> options) : base(options) { }
}

ConfigureServices

services.AddDbContextPool<AContext>(options =>
{
    options.UseInMemoryDatabase("AContext.InMemory");
});
services.AddDbContextPool<BContext>(options =>
{
    options.UseInMemoryDatabase("BContext.InMemory");
});

Controller

public class HomeController : Controller
{
    private readonly AContext aContext;

    public HomeController(AContext aContext)
    {
        this.aContext = aContext;
    }

    public IActionResult Index()
    {
        return View();
    }
}

When i use any context, exception throw.

System.ArgumentException: Expression of type 'Microsoft.EntityFrameworkCore.DbContextOptions`1[MultiContext.Contexts.BContext]' cannot be used for constructor parameter of type 'Microsoft.EntityFrameworkCore.DbContextOptions`1[MultiContext.Contexts.AContext]' Parameter name: arguments[0] at System.Dynamic.Utils.ExpressionUtils.ValidateOneArgument(MethodBase method, ExpressionType nodeKind, Expression arguments, ParameterInfo pi, String methodParamName, String argumentParamName, Int32 index) at System.Dynamic.Utils.ExpressionUtils.ValidateArgumentTypes(MethodBase method, ExpressionType nodeKind, ReadOnlyCollection`1& arguments, String methodParamName) at System.Linq.Expressions.Expression.New(ConstructorInfo constructor, IEnumerable`1 arguments) at System.Linq.Expressions.Expression.New(ConstructorInfo constructor, Expression[] arguments) at Microsoft.EntityFrameworkCore.Internal.DbContextPool`1.CreateActivator(DbContextOptions options) at Microsoft.EntityFrameworkCore.Internal.DbContextPool`1..ctor(DbContextOptions options) --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() 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.CallSiteRuntimeResolver.VisitSingleton(SingletonCallSite singletonCallSite, ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument) at Microsoft.Extensions.DependencyInjection.ServiceProvider.<>c__DisplayClass22_0.b__0(ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType) at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider provider) at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.<>c__2`1.b__2_1(IServiceProvider p) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, 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__DisplayClass22_0.b__0(ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType) at Microsoft.Extensions.Internal.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired) at lambda_method(Closure , IServiceProvider , Object[] ) at Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider.<>c__DisplayClass4_0.b__0(ControllerContext controllerContext) at Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider.<>c__DisplayClass5_0.g__CreateController0(ControllerContext controllerContext) at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.d__14.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.d__22.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context) at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.d__17.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.d__15.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNetCore.Builder.RouterMiddleware.d__4.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.d__7.MoveNext()

1
3
8/16/2017 6:04:12 AM

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Accepted Answer

Ok. i've found problem. You need to download EF Core, then change constructor for DbContextPool< TContext>

original 

public DbContextPool([NotNull] DbContextOptions options)

and change to

public DbContextPool([NotNull] DbContextOptions<TContext> options)

otherwise DI will use last added options :)

2
8/18/2017 10:28:47 AM

Popular Answer

Or you can register your own factory of DbContextPool

services.AddDbContextPool<AContext>(options =>
{
    options.UseInMemoryDatabase("AContext.InMemory");
});
services.AddDbContextPool<BContext>(options =>
{
    options.UseInMemoryDatabase("BContext.InMemory");
});

collection.AddSingleton(svcs => new DbContextPool<AContext>(svcs.GetService<DbContextOptions<AContext>>()));
collection.AddSingleton(svcs => new DbContextPool<BContext>(svcs.GetService<DbContextOptions<BContext>>()));
Aleksej Solomatin

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