在Owin启动期间,简单注入器无法注入每个Web API请求注册的类
本文关键字:Web API 请求 注册 注入 启动 Owin 注入器 简单 | 更新日期: 2023-09-27 18:18:45
我正在使用Owin, Web API,实体框架,ASP创建一个API。净的身份。我选择简单注入器作为我的DI框架。
在Owin启动过程中,我想用一些示例数据播种我的数据库。这是由实现IDatabaseInitializer
的类处理的,它看起来像这样:
public class MyDbInitializer : DropCreateDatabaseAlways<MyDataContext>
{
private readonly IUserManager _userManager;
public MyDbInitializer(IUserManager userManager)
{
_userManager = userManager;
}
protected override void Seed(MyDataContext context)
{
SeedIdentities();
}
private void SeedIdentities()
{
var user = new User
{
UserName = "someUsername",
Email = "some@email.com"
};
_userManager.CreateAsync(user, "Password");
}
IUserManager
是ASP的代理。NET标识UserManager
类,间接依赖于IUnitOfWork
。如果你想知道,IUserManager
是这样注册的:
container.Register(typeof(IUserManager),
() => container.GetInstance<IUserManagerFactory>().Create());
因为我想使用每个Web API请求的单个工作单元,我已经注册了我的IUnitOfWork
如下:
container.RegisterWebApiRequest<IUnitOfWork, MyUnitOfWork>();
除了在MyDbInitializer
类中解析IUserManager
依赖之外,这一切都工作得很好。在应用程序启动期间,SimpleInjector失败,并产生以下ActivationException:
SimpleInjector.ActivationException was unhandled by user code
HResult=-2146233088
Message=The registered delegate for type IUserManagerFactory threw an exception. The IUnitOfWork is registered as 'Web API Request' lifestyle, but the instance is requested outside the context of a Web API Request.
Source=SimpleInjector
StackTrace:
at SimpleInjector.InstanceProducer.GetInstance()
at SimpleInjector.Container.GetInstance[TService]()
at Project.WebApi.CompositionRoot.SimpleInjectorCompositionRoot.<RegisterSecurityDependencies>b__c() in c:'code'Project'Project.WebApi'CompositionRoot'SimpleInjectorCompositionRoot.cs:line 130
at lambda_method(Closure )
at lambda_method(Closure )
at SimpleInjector.InstanceProducer.GetInstance()
InnerException: SimpleInjector.ActivationException
HResult=-2146233088
Message=The IUnitOfWork is registered as 'Web API Request' lifestyle, but the instance is requested outside the context of a Web API Request.
Source=SimpleInjector
StackTrace:
at SimpleInjector.Scope.GetScopelessInstance[TService,TImplementation](ScopedRegistration`2 registration)
at SimpleInjector.Scope.GetInstance[TService,TImplementation](ScopedRegistration`2 registration, Scope scope)
at SimpleInjector.Advanced.Internal.LazyScopedRegistration`2.GetInstance(Scope scope)
at lambda_method(Closure )
at SimpleInjector.InstanceProducer.GetInstance()
InnerException:
我猜Owin Startup.cs
类被认为是在Web API请求生命周期之外,并且数据库初始化器中的构造函数注入失败,因为它是由Startup.cs
类调用的。
IUnitOfWork
,或者有更好的解决方案?
你是正确的。在启动期间,没有Web API请求。幸运的是,WebApiRequestLifestyle(由RegisterWebApiRequest
扩展方法使用)在掩护下使用ExecutionContextLifestyle,因此"模拟"web请求非常简单,如下所示:
// using SimpleInjector.Extensions.ExecutionContextScoping;
using (container.BeginExecutionContextScope())
{
var initializer = container.GetInstance<MyDbInitializer>();
intializer.InitializeDatabase();
}
另外,如果你托管在IIS中,集成的管道将为管道的每个阶段创建一个新的CallContext,这是SimpleInjector存储执行上下文的地方。
因此,如果你在一个中间件中执行BeginExecutionContextScope,而这个中间件与你的Web API代码运行的管道处于不同的阶段,那么SimpleInjector的执行上下文将不会持续存在。
您可以使用app.UseStageMarker
来调整中间件在管道中的执行位置,但我无法让SimpleInjector执行上下文持续存在于所有我的OWIN认证中间件中,然后进入Web API。下面的代码在我的DelegatingHandlerProxy中总是最终创建一个新的执行范围,尽管使用了相同的SimpleInejctor容器
protected async override Task<HttpResponseMessage> SendAsync(
HttpRequestMessage request,
CancellationToken cancellationToken)
{
// Trigger the creation of the DependencyScope to ensure the instance
// is resolved within that scope.
request.GetDependencyScope();
}