如何在Web API中使用AutoFac在运行时解析服务? [英] How to use AutoFac in Web API to resolve a service at runtime?

问题描述

我有一个API(eg: ItemController.cs)，它将在运行时从请求标头获得授权令牌.有了令牌，只有我才能进入我的服务类别(eg: ServiceItem.cs).

I have an API (eg: ItemController.cs) which would obtain the Authorization Token from the Request Header at run time. With the Token, then only I pass into my Service Class (eg: ServiceItem.cs).

这就是我的做法.

1. 在Startup.cs上，注册我的ServiceItem

1. At the Startup.cs, I register my ServiceItem

var builder = new ContainerBuilder();
builder.RegisterType<ServiceItem>();
container = builder.Build(); //Note that, my container is a static variable

在我的API中，我通过以下方式解决了该问题:

In my API, I resolve it in this way:

[Authorize]
[Route("GetData")]
[HttpGet]
public IHttpActionResult GetData([FromUri] Filter filter)
{
 using (var scope = Startup.container.BeginLifetimeScope())
 {
    var serviceItem = Startup.container.Resolve<ServiceItem>(
            new NamedParameter("token", Request.GetHeader("Authorization"))
        );
    return Ok(serviceItem.getItem(filter)); //filter is a param from webAPI
 }
}

问题:

这是Autofac在Web API中正常工作的方式吗?首先，我正在使用全局静态IContainer.其次，如果我再公开一些功能，这些代码看起来是重复的.

Is this how the Autofac normally work in web API? First, i am using a global static IContainer. Second, the codes look repetitive if i expose a few more functions.

我当时正在考虑在API的构造函数中解析ServiceItem.但是授权令牌尚不可用.

I was thinking to resolve the ServiceItem in the constructor of the API. But the authorization token is not available yet.

任何建议都值得赞赏.

PS:

这是我的ServiceItem，它在构造函数中具有参数令牌"

Here's my ServiceItem which, in the constructor, has a param 'token'

     public class ServiceItem
     {
          public string token;
          public ServiceItem(string token)
          {
              this.token = token;
          }

          public void doSomething()
          {
              //based on token, do processing
          }
      }

推荐答案

在启动类中引用静态容器是一个坏主意.这样，您将在控制器和启动之间引入紧密耦合.您的控制器依赖性应通过构造函数参数来满足.进入 http://docs.autofac.org/en/v4. 0.0/integration/aspnetcore.html

It is a bad idea to refer to a static container within your startup class. That way, you introduce tight coupling between the controller and the startup. Your controller dependencies should be satisfied by constructor parameters. Take at http://docs.autofac.org/en/v4.0.0/integration/aspnetcore.html

Startup.ConfigureServices方法可以选择返回一个IServiceProvider实例，该实例使您可以将Autofac插入ASP.NET Core依赖注入框架:

The Startup.ConfigureServices method can optionally return a IServiceProvider instance, which allows you to plug-in Autofac into the ASP.NET Core Dependency Injection framework:

public IServiceProvider ConfigureServices(IServiceCollection services)
{
  services.AddMvc();

  var builder = new ContainerBuilder();

  builder.RegisterType<MyType>().As<IMyType>();
  builder.Populate(services);
  this.ApplicationContainer = builder.Build();

  return new AutofacServiceProvider(this.ApplicationContainer);
}

初始化容器后，构造函数参数将由Autofac自动解析:

After initializing your container, constructor parameters will be automatically resolved by Autofac:

public class MyController
{
    private readonly IMyType theType;
    public MyController(IMyType theType)
    {
        this.theType = theType; 
    }

    ....
}

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