blocks|key|2683837|text|在所需的项目中，可以创建将上下文添加到集合的扩展方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2683838|public+static+class+MyDataExtensions+{
++++public+static+IServiceCollection+AddMyData(this+IServiceCollection+services)+{
++++++++//...

++++++++services.AddDbContext<MyContext>(options+=>+options.UseSqlServer(connectionString));

++++++++//...
++++}
}|code-block|syntax|javascript|2683839|然后在您的启动过程中，只需调用从其他项目公开的扩展即可|2683840|services.AddMyData();

//...other+settings|2683841|API项目是组成的根，所以无论如何它都需要知道所有相关的依赖关系。至少使用此扩展，您不必直接引用所使用的db上下文，|2683842|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

In the desired project you can create an extension method that adds the context to the collection 

<pre><code>public static class MyDataExtensions {
 public static IServiceCollection AddMyData(this IServiceCollection services) {
 //...

 services.AddDbContext&lt;MyContext&gt;(options =&gt; options.UseSqlServer(connectionString));

 //...
 }
}
</code></pre>

with that then in your start up it is just a matter of calling the extension exposed from the other project

<pre><code>services.AddMyData();

//...other settings
</code></pre>

The API project is the composition root, so it needs to know all the relevant dependencies anyway. At least with this extension you do not have to make direct reference of the used db context,

blocks|key|2683883|text|我认为问题在于您试图使用AsImplementedInterfaces()注册MyContext()。这不是DbContext通常的注册方式。您应该注册并解析类本身。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2683884|entityMap^0|C|P|13|B|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

I think that the problem is that you're trying to register <code>MyContext()</code> using <code>AsImplementedInterfaces()</code>. This is not how DbContext are getting registered usually. You should register and resolve class itself.

blocks|key|20882|text|我使用Autofac来注册HttpContextAccessor和DbContext。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|20883|builder
++++.RegisterType<HttpContextAccessor>()
++++.As<IHttpContextAccessor>()
++++.SingleInstance();

builder
++++.RegisterType<AppDbContext>()
++++.WithParameter("options",+DbContextOptionsFactory.Get())
++++.InstancePerLifetimeScope();|code-block|syntax|javascript|20884|DbContextOptionsFactory|BOLD|20885|public+class+DbContextOptionsFactory
{
++++public+static+DbContextOptions<AppDbContext>+Get()
++++{
++++++++var+configuration+=+AppConfigurations.Get(
++++++++++++WebContentDirectoryFinder.CalculateContentRootFolder());

++++++++var+builder+=+new+DbContextOptionsBuilder<AppDbContext>();
++++++++DbContextConfigurer.Configure(
++++++++++++builder,+
++++++++++++configuration.GetConnectionString(
++++++++++++++++AppConsts.ConnectionStringName));

++++++++return+builder.Options;
++++}
}|20886|DbContextConfigurer|20887|public+class+DbContextConfigurer
{
++++public+static+void+Configure(
++++++++DbContextOptionsBuilder<AppDbContext>+builder,+
++++++++string+connectionString)
++++{
++++++++builder.UseNpgsql(connectionString).UseLazyLoadingProxies();
++++}
}|20888|entityMap^0|D|J|X|9|0|0|0|N|0|0|0|J|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|10|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|11|8|@$9|12|A|13|B|M]]|D|@]|E|$]]|$1|N|3|O|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|P|3|Q|5|6|7|15|8|@$9|16|A|17|B|M]]|D|@]|E|$]]|$1|R|3|S|5|H|7|18|8|@]|D|@]|E|$I|J]]|$1|T|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|U|$]]

I use Autofac to register both <code>HttpContextAccessor</code> and <code>DbContext</code>.
<pre><code>builder
 .RegisterType&lt;HttpContextAccessor&gt;()
 .As&lt;IHttpContextAccessor&gt;()
 .SingleInstance();

builder
 .RegisterType&lt;AppDbContext&gt;()
 .WithParameter(&quot;options&quot;, DbContextOptionsFactory.Get())
 .InstancePerLifetimeScope();
</code></pre>
DbContextOptionsFactory
<pre><code>public class DbContextOptionsFactory
{
 public static DbContextOptions&lt;AppDbContext&gt; Get()
 {
 var configuration = AppConfigurations.Get(
 WebContentDirectoryFinder.CalculateContentRootFolder());

 var builder = new DbContextOptionsBuilder&lt;AppDbContext&gt;();
 DbContextConfigurer.Configure(
 builder, 
 configuration.GetConnectionString(
 AppConsts.ConnectionStringName));

 return builder.Options;
 }
}
</code></pre>
DbContextConfigurer
<pre><code>public class DbContextConfigurer
{
 public static void Configure(
 DbContextOptionsBuilder&lt;AppDbContext&gt; builder, 
 string connectionString)
 {
 builder.UseNpgsql(connectionString).UseLazyLoadingProxies();
 }
}
</code></pre>

blocks|key|20890|text|Autofac版本4.8.1的另一个简单解决方案|type|unstyled|depth|inlineStyleRanges|entityRanges|data|20891|++++public+void+ConfigureServices(IServiceCollection+services)
++++{
++++++++services.AddMvc().AddControllersAsServices();

++++++++services.AddDbContext<MyContext>(options+=>+options.UseSqlServer(Configuration.GetConnectionString("ConnectionStrings:MyConnection:ConnectionString")));

++++++++var+builder+=+new+ContainerBuilder();

++++++++builder.Populate(services);

++++++++//...
++++++++//+Your+interface+registration
++++++++//...

++++++++builder.Build(Autofac.Builder.ContainerBuildOptions.None);
++++}|code-block|syntax|javascript|20892|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Another simple solution for Autofac version 4.8.1

<pre><code> public void ConfigureServices(IServiceCollection services)
 {
 services.AddMvc().AddControllersAsServices();

 services.AddDbContext&lt;MyContext&gt;(options =&gt; options.UseSqlServer(Configuration.GetConnectionString("ConnectionStrings:MyConnection:ConnectionString")));

 var builder = new ContainerBuilder();

 builder.Populate(services);

 //...
 // Your interface registration
 //...

 builder.Build(Autofac.Builder.ContainerBuildOptions.None);
 }
</code></pre>

blocks|key|20900|text|这是我使用的一个实现-它模仿了Autofac+4.9.4中的EF+Core+3.1+registration。请确保根据您的要求调整作用域。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|20901|public+void+RegisterContext<TContext>(ContainerBuilder+builder)
++++where+TContext+:+DbContext
{
++++builder.Register(componentContext+=>
++++++++{
++++++++++++var+serviceProvider+=+componentContext.Resolve<IServiceProvider>();
++++++++++++var+configuration+=+componentContext.Resolve<IConfiguration>();
++++++++++++var+dbContextOptions+=+new+DbContextOptions<TContext>(new+Dictionary<Type,+IDbContextOptionsExtension>());
++++++++++++var+optionsBuilder+=+new+DbContextOptionsBuilder<TContext>(dbContextOptions)
++++++++++++++++.UseApplicationServiceProvider(serviceProvider)
++++++++++++++++.UseSqlServer(configuration.GetConnectionString("MyConnectionString"),
++++++++++++++++++++serverOptions+=>+serverOptions.EnableRetryOnFailure(5,+TimeSpan.FromSeconds(30),+null));

++++++++++++return+optionsBuilder.Options;
++++++++}).As<DbContextOptions<TContext>>()
++++++++.InstancePerLifetimeScope();

++++builder.Register(context+=>+context.Resolve<DbContextOptions<TContext>>())
++++++++.As<DbContextOptions>()
++++++++.InstancePerLifetimeScope();

++++builder.RegisterType<TContext>()
++++++++.AsSelf()
++++++++.InstancePerLifetimeScope();
}|code-block|syntax|javascript|20902|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/aspnet/EntityFrameworkCore/blob/40c8dbe9d45aa161a912345539675e77d114979d/src/EFCore/Extensions/EntityFrameworkServiceCollectionExtensions.cs#L476-L500^0|U|O|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Here's an implementation I use - it mimics <a href="https://github.com/aspnet/EntityFrameworkCore/blob/40c8dbe9d45aa161a912345539675e77d114979d/src/EFCore/Extensions/EntityFrameworkServiceCollectionExtensions.cs#L476-L500" rel="noreferrer">EF Core 3.1 registration</a> with Autofac 4.9.4. Be sure to adjust scopes per your requirements.

<pre><code>public void RegisterContext&lt;TContext&gt;(ContainerBuilder builder)
 where TContext : DbContext
{
 builder.Register(componentContext =&gt;
 {
 var serviceProvider = componentContext.Resolve&lt;IServiceProvider&gt;();
 var configuration = componentContext.Resolve&lt;IConfiguration&gt;();
 var dbContextOptions = new DbContextOptions&lt;TContext&gt;(new Dictionary&lt;Type, IDbContextOptionsExtension&gt;());
 var optionsBuilder = new DbContextOptionsBuilder&lt;TContext&gt;(dbContextOptions)
 .UseApplicationServiceProvider(serviceProvider)
 .UseSqlServer(configuration.GetConnectionString("MyConnectionString"),
 serverOptions =&gt; serverOptions.EnableRetryOnFailure(5, TimeSpan.FromSeconds(30), null));

 return optionsBuilder.Options;
 }).As&lt;DbContextOptions&lt;TContext&gt;&gt;()
 .InstancePerLifetimeScope();

 builder.Register(context =&gt; context.Resolve&lt;DbContextOptions&lt;TContext&gt;&gt;())
 .As&lt;DbContextOptions&gt;()
 .InstancePerLifetimeScope();

 builder.RegisterType&lt;TContext&gt;()
 .AsSelf()
 .InstancePerLifetimeScope();
}
</code></pre>

I have a new .NET Core Web API project that has the following projects structure:

API -> Business / Domain -> Infrastructure

The API is very thin with only the API methods. The Business / Domain layer has all my business logic. And finally, my Infrastructure layer has my DB classes using EF Core 2.0.

I know using .NET Core built-in Dependency Injection I can add a reference from the API project to the Infrastructure project, then add the following code in the StartUp.cs file:

<pre><code>services.AddDbContext&lt;MyContext&gt;(options =&gt; options.UseSqlServer(connectionString));
</code></pre>

However, I would like to maintain a more traditional separation of concerns. So far I have added a module in my Infrastructure layer that attempts to make the registration like so:

<pre><code>builder.Register(c =&gt;
 {
 var config = c.Resolve&lt;IConfiguration&gt;();

 var opt = new DbContextOptionsBuilder&lt;MyContext&gt;();
 opt.UseSqlServer(config.GetSection("ConnectionStrings:MyConnection:ConnectionString").Value);

 return new MyContext(opt.Options);
 }).AsImplementedInterfaces().InstancePerLifetimeScope();
</code></pre>

The DBContext, however, is not getting registered. Any class that attempts to access the injected DBContext cannot resolve the parameter. 

Is there a way to register the DBContext in a separate project using AuftoFac in a .NET Core Web API Project?

AutoFac / .NET Core - Register DBcontext

我有一个新的.NET Core Web API项目，它具有以下项目结构：应用编程接口->业务/域->基础架构API非常简单，只有API方法。业务/域层包含了我的所有业务逻辑。最后，我的基础架构层有使用EF Core 2.0的DB类。我知道使用API内置的依赖注入，我可以从.NET项目添加一个引用到基础设施项目，然后在S...

问AutoFac / .NET核心-寄存器DBcontext
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