Question

在EFCore 2.0中添加新功能，DbContext池。我知道如何在单一环境中使用它，但是，有时在项目中需要多个上下文，

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");
});

控制器

public class HomeController : Controller
{
    private readonly AContext aContext;

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

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

当我使用任何上下文时，抛出异常。

System.ArgumentException：类型＆＃39; Microsoft.EntityFrameworkCore.DbContextOptions`1 [MultiContext.Contexts.BContext]＆＃39;的表达式不能用于类型＆＃39; Microsoft.EntityFrameworkCore.DbContextOptions`1 [MultiContext.Contexts.AContext]＆＃39;的构造函数参数。参数名称：arguments [0] at System.Dynamic.Utils.ExpressionUtils.ValidateOneArgument（MethodBase方法，ExpressionType nodeKind，Expression参数，ParameterInfo pi，String methodParamName，String argumentParamName，Int32 index） at System.Dynamic.Utils.ExpressionUtils.ValidateArgumentTypes（MethodBase方法，ExpressionType nodeKind，ReadOnlyCollection`1＆amp; arguments，String methodParamName）在System.Linq.Expressions.Expression.New（ConstructorInfo构造函数，IEnumerable`1参数）在System.Linq.Expressions.Expression.New（ConstructorInfo构造函数，Expression []参数）在Microsoft.EntityFrameworkCore.Internal.DbContextPool`1.CreateActivator（DbContextOptions选项）在Microsoft.EntityFrameworkCore.Internal.DbContextPool`1..ctor（DbContextOptions选项） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw（）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor（ConstructorCallSite constructorCallSite，ServiceProvider provider）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite（IServiceCallSite callSite，TArgument参数）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped（ScopedCallSite scopedCallSite，ServiceProvider provider）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitSingleton（SingletonCallSite singletonCallSite，ServiceProvider provider）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite（IServiceCallSite callSite，TArgument参数）在Microsoft.Extensions.DependencyInjection.ServiceProvider。＆lt;＆gt; c__DisplayClass22_0.b__0（ServiceProvider provider）在Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService（类型serviceType）在Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService [T]（IServiceProvider提供程序）在Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions。＆lt;＆gt; c__2`1.b__2_1（IServiceProvider p）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory（FactoryCallSite factoryCallSite，ServiceProvider provider）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite（IServiceCallSite callSite，TArgument参数）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped（ScopedCallSite scopedCallSite，ServiceProvider provider）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite（IServiceCallSite callSite，TArgument参数）在Microsoft.Extensions.DependencyInjection.ServiceProvider。＆lt;＆gt; c__DisplayClass22_0.b__0（ServiceProvider provider）在Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService（类型serviceType）在Microsoft.Extensions.Internal.ActivatorUtilities.GetService（IServiceProvider sp，Type type，Type requiredBy，Boolean isDefaultParameterRequired）在lambda_method（Closure，IServiceProvider，Object []）在Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider。＆lt;＆gt; c__DisplayClass4_0.b__0（ControllerContext controllerContext）在Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider。＆lt;＆gt; c__DisplayClass5_0.g__CreateController0（ControllerContext controllerContext）在Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next（State＆amp; next，Scope＆amp; scope，Object＆amp; state，Boolean＆amp; isCompleted）在Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.d__14.MoveNext（） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw（）在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.d__22.MoveNext（） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw（）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow（ResourceExecutedContext context）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next（State＆amp; next，Scope＆amp; scope，Object＆amp; state，Boolean＆amp; isCompleted）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.d__17.MoveNext（） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw（）在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.d__15.MoveNext（） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw（）在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）在Microsoft.AspNetCore.Builder.RouterMiddleware.d__4.MoveNext（） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw（）在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）在Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.d__7.MoveNext（）

Answer 1

确定。我发现了问题。您需要下载EF Core，然后更改构造函数 DbContextPool＆LT; TContext＆GT;

原创

public DbContextPool([NotNull] DbContextOptions options)

并改为

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

否则DI将使用最后添加的选项：）

Answer 2

或者您可以注册自己的DbContextPool工厂

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>>()));

如何使用多DBContextPool？

2 个答案: