Access the current HttpContext in ASP.NET Core
I need to access current HttpContext
in a static method or a utility service.
With classic ASP.NET MVC and System.Web
, I would just use HttpContext.Current
to access the context statically. But how do I do this in ASP.NET Core?
HttpContext.Current
doesn't exist anymore in ASP.NET Core but there's a new IHttpContextAccessor
that you can inject in your dependencies and use to retrieve the current HttpContext
:
public class MyComponent : IMyComponent
{
private readonly IHttpContextAccessor _contextAccessor;
public MyComponent(IHttpContextAccessor contextAccessor)
{
_contextAccessor = contextAccessor;
}
public string GetDataFromSession()
{
return _contextAccessor.HttpContext.Session.GetString(*KEY*);
}
}
Necromancing.
YES YOU CAN
Secret tip for those migrating large junks chunks (sigh, Freudian slip) of code.
The following method is an evil carbuncle of a hack which is actively engaged in carrying out the express work of satan (in the eyes of .NET Core framework developers), but it works:
In public class Startup
add a property
public IConfigurationRoot Configuration { get; }
And then add a singleton IHttpContextAccessor to DI in ConfigureServices.
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<Microsoft.AspNetCore.Http.IHttpContextAccessor, Microsoft.AspNetCore.Http.HttpContextAccessor>();
Then in Configure
public void Configure(
IApplicationBuilder app
,IHostingEnvironment env
,ILoggerFactory loggerFactory
)
{
add the DI Parameter IServiceProvider svp
, so the method looks like:
public void Configure(
IApplicationBuilder app
,IHostingEnvironment env
,ILoggerFactory loggerFactory
,IServiceProvider svp)
{
Next, create a replacement class for System.Web:
namespace System.Web
{
namespace Hosting
{
public static class HostingEnvironment
{
public static bool m_IsHosted;
static HostingEnvironment()
{
m_IsHosted = false;
}
public static bool IsHosted
{
get
{
return m_IsHosted;
}
}
}
}
public static class HttpContext
{
public static IServiceProvider ServiceProvider;
static HttpContext()
{ }
public static Microsoft.AspNetCore.Http.HttpContext Current
{
get
{
// var factory2 = ServiceProvider.GetService<Microsoft.AspNetCore.Http.IHttpContextAccessor>();
object factory = ServiceProvider.GetService(typeof(Microsoft.AspNetCore.Http.IHttpContextAccessor));
// Microsoft.AspNetCore.Http.HttpContextAccessor fac =(Microsoft.AspNetCore.Http.HttpContextAccessor)factory;
Microsoft.AspNetCore.Http.HttpContext context = ((Microsoft.AspNetCore.Http.HttpContextAccessor)factory).HttpContext;
// context.Response.WriteAsync("Test");
return context;
}
}
} // End Class HttpContext
}
Now in Configure, where you added the IServiceProvider svp
, save this service provider into the static variable "ServiceProvider" in the just created dummy class System.Web.HttpContext (System.Web.HttpContext.ServiceProvider)
and set HostingEnvironment.IsHosted to true
System.Web.Hosting.HostingEnvironment.m_IsHosted = true;
this is essentially what System.Web did, just that you never saw it (I guess the variable was declared as internal instead of public).
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IServiceProvider svp)
{
loggerFactory.AddConsole(Configuration.GetSection("Logging"));
loggerFactory.AddDebug();
ServiceProvider = svp;
System.Web.HttpContext.ServiceProvider = svp;
System.Web.Hosting.HostingEnvironment.m_IsHosted = true;
app.UseCookieAuthentication(new CookieAuthenticationOptions()
{
AuthenticationScheme = "MyCookieMiddlewareInstance",
LoginPath = new Microsoft.AspNetCore.Http.PathString("/Account/Unauthorized/"),
AccessDeniedPath = new Microsoft.AspNetCore.Http.PathString("/Account/Forbidden/"),
AutomaticAuthenticate = true,
AutomaticChallenge = true,
CookieSecure = Microsoft.AspNetCore.Http.CookieSecurePolicy.SameAsRequest
, CookieHttpOnly=false
});
Like in ASP.NET Web-Forms, you'll get a NullReference when you're trying to access a HttpContext when there is none, such as it used to be in Application_Start
in global.asax.
I stress again, this only works if you actually added
services.AddSingleton<Microsoft.AspNetCore.Http.IHttpContextAccessor, Microsoft.AspNetCore.Http.HttpContextAccessor>();
like I wrote you should.
Welcome to the ServiceLocator pattern within the DI pattern ;)
For risks and side effects, ask your resident doctor or pharmacist - or study the sources of .NET Core at github.com/aspnet, and do some testing.
Perhaps a more maintainable method would be adding this helper class
namespace System.Web
{
public static class HttpContext
{
private static Microsoft.AspNetCore.Http.IHttpContextAccessor m_httpContextAccessor;
public static void Configure(Microsoft.AspNetCore.Http.IHttpContextAccessor httpContextAccessor)
{
m_httpContextAccessor = httpContextAccessor;
}
public static Microsoft.AspNetCore.Http.HttpContext Current
{
get
{
return m_httpContextAccessor.HttpContext;
}
}
}
}
And then calling HttpContext.Configure in Startup->Configure
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IServiceProvider svp)
{
loggerFactory.AddConsole(Configuration.GetSection("Logging"));
loggerFactory.AddDebug();
System.Web.HttpContext.Configure(app.ApplicationServices.
GetRequiredService<Microsoft.AspNetCore.Http.IHttpContextAccessor>()
);
The most legit way I came up with was by injecting IHttpContextAccessor in your static implementation as follow:
public static class HttpHelper
{
private static IHttpContextAccessor _accessor;
public static void Configure(IHttpContextAccessor httpContextAccessor)
{
_accessor = httpContextAccessor;
}
public static HttpContext HttpContext => _accessor.HttpContext;
}
Then assigning the IHttpContextAccessor in the Startup Configure should do the job.
HttpHelper.Configure(app.ApplicationServices.GetRequiredService<IHttpContextAccessor>());
I guess you should also need to register the service singleton:
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();