如何使用DI在类构造函数中获取Microsoft.AspNet.Http.HttpContext实例 [英] How to get Microsoft.AspNet.Http.HttpContext instance in Class Constructor using DI
问题描述
我正在MVC 6中构建一个一次性应用程序,并尝试使用不同的体系结构来进行依赖.
I am building a throwaway application in MVC 6 and experimenting with different architectures for dependencies.
我面临的问题是如何创建特定于应用程序的自定义"MyAppContext
"对象.这将需要HttpContext
中的某些信息以及数据库中的某些信息,并且将成为针对应用程序特定属性的请求范围的存储库.我想将HttpContext
的实例传递到'MyAppContext
'的构造函数中.
The problem I am facing is how to create a custom 'MyAppContext
' object specific to the Application. This would require some information from the HttpContext
and some information from the database, and will be a request-scoped repository for application specific attributes. I want to pass the instance of the HttpContext
into the constructor of the 'MyAppContext
'.
我已经使用DI成功创建了一个具有IDataService
接口的'DataService
'对象,并且工作正常.
与"MyAppContext"类的区别在于,它在构造函数中具有两个参数-"DataService
"和Microsoft.AspNet.Http.HttpContext
.这是MyAppContext类:
I have successfully created a 'DataService
' object with an IDataService
interface using DI and this works Ok.
The difference with the 'MyAppContext' class is that it has two parameters in the constructor - the 'DataService
' and the Microsoft.AspNet.Http.HttpContext
. Here is the MyAppContext class:
public class MyAppContext : IMyAppContext
{
public MyAppContext(IDataService dataService, HttpContext httpContext)
{
//do stuff here with the httpContext
}
}
在启动代码中,我注册了DataService实例和MyAppContext实例:
In the startup code, I register the DataService instance and the MyAppContext instance:
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
//adds a singleton instance of the DataService using DI
services.AddSingleton<IDataService, DataService>();
services.AddScoped<IMyAppContext, MyAppContext>();
}
public void Configure(IApplicationBuilder app)
{
app.UseErrorPage();
app.UseRequestServices();
app.UseMvc(routes => /* routes stuff */);
}
我期望DI中解析构造函数中的HttpContext
参数.
运行代码时,这是我返回的异常:
I am expecting the HttpContext
parameter in the constructor to get resolved by DI.
When running the code, this is the exception I get returned:
InvalidOperationException:尝试激活"MyAppContext"时无法解析类型为"Microsoft.AspNet.Http.HttpContext"的服务
InvalidOperationException: Unable to resolve service for type 'Microsoft.AspNet.Http.HttpContext' while attempting to activate 'MyAppContext'
我认为这是因为没有特定的HttpContext
实例发生此错误,但是我不知道如何在DI中注册HttpContext
实例.我添加了行"app.UseRequestServices();
",但这没有任何区别.我还尝试了以下方法的变体:
I figure this is because there is no specific instance of HttpContext
that this error is occurring, but I don't know how to register the HttpContext
instance in DI. I added the line 'app.UseRequestServices();
' but this hasn't made any difference. I also tried a variant of:
services.AddScoped<HttpContext, HttpContext>();
但是这失败了,因为第二个HttpContext
应该是一个实例-我知道这是不正确的,但是还无法弄清是什么.
But this fails because the second HttpContext
is supposed to be an instance - I know it's not correct but haven't been able to work out what is.
因此,总而言之-如何将HttpContext
对象传递到MyAppContext的构造函数中?
So, in summary - how can I pass in the HttpContext
object into the constructor of MyAppContext?
推荐答案
在构造函数中注入IHttpContextAccessor
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