c# - 在何处使用依赖注入(inject)注册上下文

Question

根据 this教程我应该:

使用依赖注入(inject)注册你的上下文

教程描述了我应该找到方法ConfigureServices() 并将建议的代码放入其中。

这是我的 startup.cs :

using Microsoft.Owin;
using Owin;

[assembly: OwinStartupAttribute(typeof(MyProject.Startup))]
namespace MyProject
{
    public partial class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            ConfigureAuth(app);
        }
    }
}

所以我不知道该把代码放在哪里。

由于项目不兼容.net core 2.1，需要将Project->Property改为.Net Framework 4.6.1并安装包 Microsoft.EntityFrameworkCore.SqlServer 和 Microsoft.EntityFrameworkCore.Tools

我尝试将依赖注入(inject)添加到 global.asax.cs文件如下:

protected void Application_Start()
        {
            var services = new ServiceCollection();
            ConfigureServices(services);
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
}

private void ConfigureServices(IServiceCollection services)
    {
        var connection = @"Server=(localdb)\mssqllocaldb;Database=Blogging;Trusted_Connection=True;ConnectRetryCount=0";
        services.AddDbContext<BloggingContext>(options => options.UseSqlServer(connection));
    }

我成功完成了这一步并创建了 Controller 并且它可以工作，但是我没有选择正确的上下文 (BloggingContext)，所以它创建了第二个数据库。所以，我需要用 BloggingContext 创建一个 Controller ，你知道怎么做吗？

Answer 1

显示的启动版本和教程相互冲突。

如果这是 Asp.Net Core MVC 应用程序，那么您可以自己添加该方法。 Startup 类是约定的一部分。

public partial class Startup {
    //...

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
         //...
    }
}

引用 App startup in ASP.NET Core

The ConfigureServices method

The ConfigureServices method is:

• Optional.
• Called by the host before the Configure method to configure the app's services.
• Where configuration options are set by convention.

---

但是，如果您尝试在 Asp.Net MVC 5+ (这是 GitHub 项目的目标)中使用 .Net Core 技术，那么您将需要修改您的方法以适应使用.Net 核心依赖注入(inject)与非核心平台。

首先，您需要一个 IDependencyResolver(该版本的 Asp.Net MVC 使用的 DI 框架)，以及一种用您自己的解析器替换默认解析器的方法。

public sealed class CoreDependencyResolver : System.Web.Mvc.IDependencyResolver {
    private readonly System.Web.Mvc.IDependencyResolver mvcInnerResolver;
    private readonly IServiceProvider serviceProvider;

    public CoreDependencyResolver(IServiceProvider serviceProvider, System.Web.Mvc.IDependencyResolver dependencyResolver) {
        this.serviceProvider = serviceProvider;
        mvcInnerResolver = dependencyResolver;
    }

    public object GetService(Type serviceType) {
        object result = this.serviceProvider.GetService(serviceType);
        if (result == null && mvcInnerResolver != null)
            result = mvcInnerResolver.GetService(serviceType);
        return result;
    }

    public IEnumerable<object> GetServices(Type serviceType) {
        IEnumerable<object> result = this.serviceProvider.GetServices(serviceType);
        if (result == null && mvcInnerResolver != null)
            result = mvcInnerResolver.GetServices(serviceType);
        return result ?? new object[0];
    }
}

自定义解析器就位后，您现在可以配置应用程序以使用它。

以您当前的示例为起点(评论意见)

protected void Application_Start() {
    var services = new ServiceCollection();
    ConfigureServices(services);
    //build service provider
    IServiceProvider provider = services.BuildServiceProvider();
    //Get the current resolver used by MVC
    var current = DependencyResolver.Current;
    //use that and the provider to create your custom resolver
    var resolver = new CoreDependencyResolver(provider, current);
    //now set the MVC framework to use the resolver that wraps the service provider
    //that was created from .Net Core Dependency Injection framework.
    DependencyResolver.SetResolver(resolver);
    //...

    AreaRegistration.RegisterAllAreas();
    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    BundleConfig.RegisterBundles(BundleTable.Bundles);
}

private void ConfigureServices(IServiceCollection services) {
    //... omitted for brevity (register dependencies as normal)
}