使用DbContext接口注册AspNetCore 2.1身份系统 [英] Register AspNetCore 2.1 Identity system with DbContext interface

问题描述

我正在研究AspNetCore 2.1 WebApi.我正在使用Microsoft.Extensions.DependencyInjection，AspNetCore.Identity和EntityFrameworkCore.

I am working on an AspNetCore 2.1 WebApi. I am using Microsoft.Extensions.DependencyInjection, AspNetCore.Identity, and EntityFrameworkCore.

在我的DI注册中，我打电话:

In my DI registrations, I am calling:

services.AddDbContext<IMyDbContext, MyDbContext>();

好吧?传递合同.但是然后我遇到一个例外，即Identity Manager类(UserManager，RoleManager等)无法在依赖注入容器中重新分配，因为它们使用的身份存储(UserStore，RoleStore等)不能解析其DI参数(MyDbContext).

Good, right? Pass around the contract. But then I hit an exception that the Identity Manager classes (UserManager, RoleManager, etc.) cannot be respolved in the Dependency Injection container because the Identity Stores they use (UserStore, RoleStore, etc.) cannot resolve their DI parameter (MyDbContext).

设置身份时，所有内容都指向此行:

It all points to this line when setting up Identity:

builder.AddEntityFrameworkStores<MyDbContext>();

...这很奇怪，因为身份存储正在寻找具体的上下文，并且未在DI中注册.该扩展期望它可以解析为DbContext的class，并且我不能在接口IMyDbContext上添加隐式运算符以为其提供DI扩展方法可以使用的隐式强制转换.

... which is puking since the Identity Stores are looking for the concrete context and it is not registered with DI. The extension is expecting a class that it can resolve down to DbContext - and I cannot add an implicit operator to the interface IMyDbContext to give it an implicit cast the DI extension method could use.

所有这些使我执行了相当难看的DI注册:

All this has me performing a rather ugly DI registration:

services
        .AddDbContext<IMyDbContext, MyDbContext>()
        .AddDbContext<MyDbContext>();

• DI注册可能会导致我尚未遇到的其他下游问题(线程安全，事务性).

我的猜测是，我可以滚动自己的IServiceCollection扩展名和/或自定义身份存储来清理DI注册-这在这里似乎实在是太过分了，因为否则我无需超出默认的内置身份商店.

My guess is that I could clean up the DI registration by rolling my own IServiceCollection extension and/or custom Identity Stores - which really seems like overkill here as I otherwise have no need to go beyond the default built-in Identity Stores.

我也不是很想删除<interface, concrete>上下文注册，因为这会滴加到我所有的构造函数注入中，而且看起来错误.

I also don't really want to remove the <interface, concrete> context registration as that will trickle down to all my constructor injections, and just seems wrong.

有人解决了这个问题并找到了解决方法吗? 还是至少有人可以确认/否认DI中的双重(接口和具体)上下文注册不会引起其他问题?

Has anybody tackled this already and found a work-around? Or can anybody at least confirm/deny that the double (interface && concrete) context registration in the DI will not cause other issues?

提前谢谢！

推荐答案

默认情况下，调用AddDbContext时，您注册了作用域 DbContext实例.这意味着在处理单个请求的任何地方，通过DI请求所述DbContext都会给您相同实例.进行双重注册后，DI系统会根据您要求的是IMyDbContext还是MyDbContext，为您提供不同的实例.

By default, when you call AddDbContext, you register a scoped DbContext instance. This means that anywhere within the handling of a single request, requesting said DbContext via DI will give you the same instance. With the double registration you have, the DI system will give you a different instance depending upon whether you ask for an IMyDbContext or a MyDbContext.

要指示DI系统为您提供两种类型的相同实例，请使用以下方法:

To instruct the DI system to give you the same instance for both types, use the following approach:

services.AddDbContext<MyDbContext>();
services.AddScoped<IMyDbContext>(sp => sp.GetRequiredService<MyDbContext>());

第一个调用注册MyDbContext，第二个简单地将对IMyDbContext的请求转发到同一作用域MyDbContext实例.

The first call registers MyDbContext and the second simply forwards requests for IMyDbContext to that same scoped MyDbContext instance.

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