Autofac/FluentValidation:从请求实例的作用域中看不到具有匹配'AutofacWebRequest'的标记的作用域

Question

尝试将数据注入FluentValidation验证器:

public class MyFormValidator : AbstractValidator<MyForm>
{
    private readonly IQueryable<Models.User> _users;

    public MyFormValidator(IQueryable<Models.User> users)
    {
        _users = users;
        ...
    }
}

我的验证工厂:

public class DependencyResolverValidatorFactory : ValidatorFactoryBase
{
    private readonly IContainer container;

    public DependencyResolverValidatorFactory(IContainer container)
    {
        this.container = container;
    }

    public override IValidator CreateInstance(Type validatorType)
    {
        return container.ResolveOptionalKeyed<IValidator>(validatorType);
    }
}

我的Autofac配置器:

public class AutofacConfigurator
{
    public static void Configure()
    {
        var builder = new ContainerBuilder();
        ...

        builder.RegisterType<MyFormValidator>()
            .Keyed<IValidator>(typeof(IValidator<MyForm>))
            .As<IValidator>()
             // 2nd parameter returns IQueryable<User>
            .WithParameter("users", new SqlRepository<User>(dataContext)) 
            .InstancePerRequest();

        builder.RegisterSource(new AnyConcreteTypeNotAlreadyRegisteredSource());

        var container = builder.Build();

        DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

        // Register the validator factory with FluentValidation, and register 
        // FluentValidation as the model validator provider for the MVC framework. 
        // see http://www.jerriepelser.com/blog/using-fluent-validation-with-asp-net-mvc-part-3-adding-dependency-injection
        var fluentValidationModelValidatorProvider = 
            new FluentValidationModelValidatorProvider(
                new DependencyResolverValidatorFactory(container));
        DataAnnotationsModelValidatorProvider.AddImplicitRequiredAttributeForValueTypes = false;
        fluentValidationModelValidatorProvider.AddImplicitRequiredValidator = false;
        ModelValidatorProviders.Providers.Add(fluentValidationModelValidatorProvider);

    }
}

获得以下异常:

从请求实例的作用域中看不到具有匹配"AutofacWebRequest"的标记的作用域.这通常表示SingleInstance()组件(或类似场景)正在请求注册为每HTTP请求的组件.在Web集成下,始终从DependencyResolver.Current或ILifetimeScopeProvider.RequestLifetime请求依赖项,从不从容器本身请求.

我有其他验证器,其中大部分都不需要注入数据.

这对我来说是很大的新理由(在Autofac和FluentValidation中),我仍在努力理解我在这里做的事情.我怀疑我只是错误地注册我的类型.我如何解决此问题并正确注册我的类型？

(如果这与已经提出的其他问题过于相似,我表示道歉.)

Answer 1

我对FluentValidation缺乏经验,但我怀疑这是你问题的原因,所以无论如何我都会向前推进.

您获得的例外意味着Autofac无法将您的服务解析为"每个请求的实例".关于Autofac 文档页面上的含义,有很多文档.总而言之,这意味着Autofac将尝试从为发送到Web服务器的每个请求自动创建的生命周期范围中解析服务.当您注册某些内容.InstancePerRequestScope()但然后尝试在该范围之外解析该服务时,您会DependencyResolutionException看到.

所以我们已经确定你MyFormValidator的"请求"范围没有得到解决.为什么？

DependencyResolverValidatorFactory您编写的自定义IContainer采用Autofac构建的实际,并从中解析.这是一种特殊类型ILifetimeScope的"根范围".没有与此直接关联的请求生命周期范围,因此您将获得异常.您需要ILifetimeScope从"请求"范围或请求范围中包含的子范围开始解析.

Autofac/MVC集成已经自动托管请求范围(在AutofacDependencyResolver查看源代码中),但您的自定义DependencyResolverValidatorFactory不能从中解析.如果你想这样做,我想你可以修改你DependencyResolverValidatorFactory的接受AutofacDependencyResolver实例,然后用它来解决.

它看起来像这样:

public class DependencyResolverValidatorFactory : ValidatorFactoryBase
{
    private readonly AutofacDependencyResolver resolver;

    public DependencyResolverValidatorFactory(AutofacDependencyResolver resolver)
    {
        this.resolver = resolver;
    }

    public override IValidator CreateInstance(Type validatorType)
    {
        return resolver.RequestLiftimeScope.ResolveOptionalKeyed<IValidator>(validatorType);
    }
}

注意RequestLifetimeScope卡在那里.然后在您的.Configure()方法中使用创建它

var resolver = new AutofacDependencyResolver(container);
DependencyResolver.SetResolver(resolver);

var fluentValidationModelValidatorProvider = 
    new FluentValidationModelValidatorProvider(
        new DependencyResolverValidatorFactory(resolver));

这应该摆脱异常,假设这个工厂确实有一个请求在创建IValidators的实例时工作.如果没有,您可能需要使用默认行为(.InstancePerDependency()每次请求时创建新实例)或单例(.SingleInstance())进行注册,具体取决于验证者可以或应该如何共享.

祝好运.