I want to attempt something and I hope it is possible. I want a global property, containing the site base URL, that I can use across my application dlls. Here is what I thought of so far, while configuring my Dependency Injection:
public static IServiceCollection AddOrderEasyDependencies(this IServiceCollection services, IConfiguration configuration)
{
// Set golbal properties and configurations
var xxx = services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
RunningConfig runningConfig = new(xxx);
services.AddSingleton<IRunningConfig>(runningConfig);
}
Then the RunningConfig looks like this:
public class RunningConfig: IRunningConfig
{
private readonly IHttpContextAccessor _httpContextAccessor;
public string SiteUrl {
get
{
var httpContext = _httpContextAccessor.HttpContext;
var url = httpContext.Request.Scheme + "://" + httpContext.Request.Host.Value;
return url;
}
}
public RunningConfig(IServiceCollection services)
{
_httpContextAccessor = services.BuildServiceProvider().GetService<IHttpContextAccessor>();
}
}
IRunningConfig is just an interface with a property.
I have services.AddHttpContextAccessor(); in my ConfigureServices method in the startup class.
My problem is that IHttpContextAccessor is always null no matter how I do my injection. Please tell me what I am doing wrong or suggest a better way to do something like this.
I call the IRunningConfig like this:
public class SomeService: IService
{
private readonly IRunningConfig _runningConfig;
public SomeService(IServiceProvider services)
{
_runningConfig = services.GetService<IRunningConfig>();
}
public void DoMethodStuff()
{
var urlAddress = _runningConfig.SiteUrl;
}
}
Why are you using services.BuildServiceProvider()? Every time you are building new Provider and Singleton is not realy Singleton any more. You have to use DI
I would do it like this
public static IServiceCollection AddOrderEasyDependencies(this IServiceCollection services, IConfiguration configuration)
{
// Set golbal properties and configurations
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
// For IHttpContextAccessor registration there is an extention mehod in Microsoft.Extensions.DependencyInjection
// services.AddHttpContextAccessor();
services.AddSingleton<IRunningConfig, RunningConfig>();
}
public class RunningConfig: IRunningConfig
{
private readonly IHttpContextAccessor _httpContextAccessor;
public string SiteUrl {
get
{
var httpContext = _httpContextAccessor.HttpContext;
var url = httpContext.Request.Scheme + "://" + httpContext.Request.Host.Value;
return url;
}
}
public RunningConfig(IHttpContextAccessor httpContextAccessor)
{
_httpContextAccessor = httpContextAccessor;
}
}
Related
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>();
Just to add to the other answers...
In ASP.NET Core 2.1, there's the AddHttpContextAccessor extension method, that will register the IHttpContextAccessor with the correct lifetime:
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpContextAccessor();
// Other code...
}
}
According to this article: Accessing HttpContext outside of framework components in ASP.NET Core
namespace System.Web
{
public static class HttpContext
{
private static IHttpContextAccessor _contextAccessor;
public static Microsoft.AspNetCore.Http.HttpContext Current => _contextAccessor.HttpContext;
internal static void Configure(IHttpContextAccessor contextAccessor)
{
_contextAccessor = contextAccessor;
}
}
}
Then:
public static class StaticHttpContextExtensions
{
public static void AddHttpContextAccessor(this IServiceCollection services)
{
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}
public static IApplicationBuilder UseStaticHttpContext(this IApplicationBuilder app)
{
var httpContextAccessor = app.ApplicationServices.GetRequiredService<IHttpContextAccessor>();
System.Web.HttpContext.Configure(httpContextAccessor);
return app;
}
}
Then:
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpContextAccessor();
}
public void Configure(IApplicationBuilder app)
{
app.UseStaticHttpContext();
app.UseMvc();
}
}
You can use it like this:
using System.Web;
public class MyService
{
public void DoWork()
{
var context = HttpContext.Current;
// continue with context instance
}
}
In Startup
services.AddHttpContextAccessor();
In Controller
public class HomeController : Controller
{
private readonly IHttpContextAccessor _context;
public HomeController(IHttpContextAccessor context)
{
_context = context;
}
public IActionResult Index()
{
var context = _context.HttpContext.Request.Headers.ToList();
return View();
}
}
To access to the session object from a class without explicitly use dependency injection in class constructor follow the next steps:
Add a Singleton instance on Startup.cs (ConfigureServices):
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
In your target class declare an instance of HttpContextAccessor:
IHttpContextAccessor _httpContextAccessor = new HttpContextAccessor();
Access to the session object :
string mySessionVar = _httpContextAccessor.HttpContext.Session.GetString("_MySessionVar");
EXAMPLE
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}
YourClass.cs
public class YourClass {
public string yourProperty {
get{
IHttpContextAccessor _httpContextAccessor = new HttpContextAccessor();
return _httpContextAccessor.HttpContext.Session.GetString("_YourSessionVar");
}
}
}
Enjoy :)
I wish to check various session values from within my custom class. One thing I want to test is if the LoggedIn variable is set when a user hits a specific page. I want to do this in a class so I don't have to repeat code.
Here is how I've registered the service / IHttpContextAccessor:
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddScoped<clsSessionHelper>();
services.AddRazorPages();
services.AddMvc().AddRazorPagesOptions(options =>
{
options.Conventions.AddPageRoute("/App/Mpl/MplHome/MplHome", "");
});
services.AddAntiforgery(o => o.HeaderName = "XSRF-TOKEN");
services.AddDistributedMemoryCache();
services.AddSession(options =>
{
options.IdleTimeout = TimeSpan.FromSeconds(1200);
options.Cookie.HttpOnly = true;
options.Cookie.IsEssential = true;
});
// End Session Support
services.AddMemoryCache();
}
Here is how I've build the custom class:
public class clsSessionHelper
{
private readonly IHttpContextAccessor _httpContextAccessor;
private readonly ISession _session;
public clsSessionHelper(IHttpContextAccessor httpContextAccessor)
{
_httpContextAccessor = httpContextAccessor;
_session = _httpContextAccessor.HttpContext.Session;
}
public string getValue(string SessionKey)
{
string strResult = _session.GetString(SessionKey);
return strResult;
}
When I try to use the my helper class in a xx.cshtml.cs file like be below
clsSessionHelper objSessionHelper = new clsSessionHelper();
Test = objSessionHelper.getValue("LoggedIn");
I get an intellsense error "there is no argument given that corresponds to the required formal parameter 'httpContextAccessor' of 'clsSessionHelper.clsSessionHelper(HttpContextAccessor)'.
No doubt, I'm messing up the dependency injection. Any help would be greatly appreaciated.
The issue is that at the time the custom class is initialized and the IHttpContextAccessor injected, it is too early in the request process to have access to the HttpContext and by extension the ISession
Move any code that depend on the HttpContext out of the construct and into a member that is invoked during the context of a request.
public class clsSessionHelper : ISessionHelper {
private readonly IHttpContextAccessor httpContextAccessor;
public clsSessionHelper(IHttpContextAccessor httpContextAccessor) {
this.httpContextAccessor = httpContextAccessor;
}
public string getValue(string SessionKey) {
ISession session = httpContextAccessor.HttpContext.Session;
string strResult = session.GetString(SessionKey);
return strResult;
}
}
Also abstract your custom class
public interface ISessionHelper {
string getValue(string SessionKey);
}
so it too can be injected where needed.
//...
services.AddScoped<ISessionHelper, clsSessionHelper>();
//...
Avoid trying to initialize it manually.
private readonly ISessionHelper objSessionHelper;
public MyPageModel(ISessionHelper objSessionHelper) {
this.objSessionHelper = objSessionHelper;
}
public async Task<IActionResult> OnGet() {
var Test = objSessionHelper.getValue("LoggedIn");
//...
}
I have a multi-tenant ASP.NET Core web application. The current tenancy model is every tenant has a separate web app and SQL database. I'm trying to rearchitect it so that multiple tenants will be served by a single web app (but maintaining a separate database per tenant). I've been following this series of blog posts but I've hit a bit of a roadblock with configuration.
The app makes heavy use of the ASP.NET Core configuration system, and has a custom EF Core provider that fetches config values from the database. I'd like to preserve this if possible, it would be an awful lot of work to rip out and replace with something else (dozens of config settings used in hundreds of places).
The existing code is very standard:
public class MyAppSettings
{
public string FavouriteColour { get; set; }
public int LuckyNumber { get; set; }
}
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public void ConfigureServices(IServiceCollection services)
{
services.AddOptions();
services.Configure<MyAppSettings>(Configuration.GetSection("MyAppSettings"));
// etc....
}
}
// custom EF Core config provider wired up in Program.Main, but that doesn't actually seem relevant
I've already updated our custom provider so that it fetches all configuration values from all known tenant databases, and adds them all to the configuration system, prefixed with a tenant identifier, so the list of all config values fetched from the n different databases might look something like this:
Key Value
===============================================
TenantABC:MyAppSettings:FavouriteColour Green
TenantABC:MyAppSettings:LuckyNumber 42
TenantDEF:MyAppsettings:FavouriteColour Blue
TenantDEF:MyAppSettings:LuckyNumber 37
...
TenantXYZ:MyAppSettings:FavouriteColour Yellow
TenantXYZ:MyAppSettings:LuckyNumber 88
What I'd like to be able to do is somehow customise the way that the configuration is bound so that it resolves the tenant for the current request, and then uses the appropriate values, e.g. a request on abc.myapp.com would observe config values "Green" and "42", etc, without having to change all the dependent places that inject IOptionsMonitor<AppSettings> (or IOptionsSnapshot, etc). The linked blog series has a post about configuration that covers some gotchas that I expect I'll eventually run into around caching etc, but it doesn't seem to cater for this scenario of using completely different settings for different tenants. Conceptually it seems simple enough, but I haven't been able to find the correct place to hook in. Please help!
Here is an idea (not tested yet, however). You can save the default IConfiguration instance passed to the constructor of your Startup class and then register in DI your own implementation of IConfiguration that will use that default one and HttpContextAccessor (to get the current tenant).
So the code will look something like:
public class Startup
{
private IConfiguration _defaultConfig;
public Startup(IConfiguration configuration, IWebHostEnvironment env)
{
_defaultConfig = configuration;
}
public void ConfigureServices(IServiceCollection services)
{
. . . .
services.AddScoped<IConfiguration>(serviceProvider => {
var httpContextAccessor =
serviceProvider.GetService<IHttpContextAccessor>();
return new MyConfig(_defaultConfig, httpContextAccessor);
});
}
. . . .
}
public class MyConfig : IConfiguration
{
private readonly IConfiguration _defaultConfig;
private readonly IHttpContextAccessor _httpContextAccessor;
public MyConfig(IConfiguration defaultConfig, IHttpContextAccessor httpContextAccessor)
{
_defaultConfig = defaultConfig;
_httpContextAccessor = httpContextAccessor;
}
public string this[string key] {
get {
var tenantId = GetTenantId();
return _defaultConfig[tenantId + ":" + key];
}
set {
var tenantId = GetTenantId();
_defaultConfig[tenantId + ":" + key] = value;
}
}
protected virtual string GetTenantId()
{
//this is just an example that supposes that you have "TenantId" claim associated with each user
return _httpContextAccessor.HttpContext.User.FindFirst("TenantId").Value; ;
}
public IEnumerable<IConfigurationSection> GetChildren()
{
return _defaultConfig.GetChildren();
}
public IChangeToken GetReloadToken()
{
return _defaultConfig.GetReloadToken();
}
public IConfigurationSection GetSection(string key)
{
var tenantId = GetTenantId();
return _defaultConfig.GetSection(tenantId + ":" + key);
}
}
Here are 3 solutions that may be helpful. I don't recommend you the IOptionsMonitor<T> because the tenant value is extracted from HttpContext, makes no sense to use the IOptionsMonitor.
Shared code:
public static class Extensions
{
public static string GetTenantName(this HttpContext context)
{
switch (context.Request.Host.Host)
{
case "abc.localhost.com":
return "TenantABC";
case "def.localhost.com":
return "TenantDEF";
default:
throw new IndexOutOfRangeException("Invalid host requested");
}
}
public static MyAppSettings GetAppSettingsByTenant(this IConfiguration config, string tenant)
{
return new MyAppSettings
{
LuckyNumber = int.Parse(config[$"{tenant}:MyAppSettings:LuckyNumber"]),
FavouriteColour = config[$"{tenant}:MyAppSettings:FavouriteColour"]
};
}
}
Solution 1: Scoped MyAppSettings object.
Registration (Startup->ConfigureServices(IServiceCollection)`
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddScoped(sp =>
{
var contextAccessor = sp.GetService<IHttpContextAccessor>();
var config = sp.GetService<IConfiguration>();
return config.GetAppSettingsByTenant(contextAccessor.HttpContext.GetTenantName());
});
...
Usage:
public class TestController : Controller
{
private readonly MyAppSettings _settings;
public TestController(MyAppSettings settings)
{
_settings = settings;
}
[HttpGet]
public IActionResult Index()
{
return Json(_settings);
}
}
Solution 2: IOptions<MyAppSettings
Registration (Startup->ConfigureServices(IServiceCollection)`
public class MyAppSettingsOptions : IOptions<MyAppSettings>
{
public MyAppSettingsOptions(IConfiguration configuration, IHttpContextAccessor contextAccessor)
{
var tenant = contextAccessor.HttpContext.GetTenantName();
Value = configuration.GetAppSettingsByTenant(tenant);
}
public MyAppSettings Value { get; }
}
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddScoped<IOptions<MyAppSettings>, MyAppSettingsOptions>();
...
Usage
public class TestController : Controller
{
private readonly IOptions<MyAppSettings> _options;
public TestController(IOptions<MyAppSettings> options)
{
_options = options;
}
[HttpGet]
public IActionResult Index()
{
return Json(_options.Value);
}
}
Solution 3: IOptionsMonitor<MyAppSettings
Registration (Startup->ConfigureServices(IServiceCollection)`
public class MyAppSettingsOptionsMonitor : IOptionsMonitor<MyAppSettings>
{
public MyAppSettingsOptionsMonitor(IConfiguration configuration, IHttpContextAccessor contextAccessor)
{
var tenant = contextAccessor.HttpContext.GetTenantName();
CurrentValue = configuration.GetAppSettingsByTenant(tenant);
}
public MyAppSettings Get(string name)
{
throw new NotSupportedException();
}
public IDisposable OnChange(Action<MyAppSettings, string> listener)
{
return null;
}
public MyAppSettings CurrentValue { get; }
}
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddScoped<IOptionsMonitor<MyAppSettings>, MyAppSettingsOptionsMonitor>();
...
Usage
public class TestController : Controller
{
private readonly IOptionsMonitor<MyAppSettings> _options;
public TestController(IOptionsMonitor<MyAppSettings> options)
{
_options = options;
}
[HttpGet]
public IActionResult Index()
{
return Json(_options.CurrentValue);
}
}
You can use DI services to config options
Sample code of your option class
public class MyAppSettings
{
public string FavouriteColor { get; set; }
public int LuckNumber { get; set; }
}
public interface IMySettingServices
{
string GetFavouriteColor();
int GetLuckNumber();
}
public class MySettingServices : IMySettingServices
{
private IHttpContextAccessor httpContextAccessor;
public MySettingServices(IHttpContextAccessor httpContextAccessor)
{
this.httpContextAccessor = httpContextAccessor;
}
public string GetFavouriteColor()
{
var headers = this.httpContextAccessor.HttpContext.Request.Headers;
//Write your logic with httpContextAccessor by extract tenant here, then return actual config by tenant name
if(this.httpContextAccessor.HttpContext.Request.Host.Host=="abc.test.com")
{
//Get color setting for abc.test.com
}
return "Green";
}
public int GetLuckNumber()
{
var headers = this.httpContextAccessor.HttpContext.Request.Headers;
//Write your logic with httpContextAccessor by extract tenant here, then return actual config by tenant name
if (this.httpContextAccessor.HttpContext.Request.Host.Host == "abc.test.com")
{
//Get luck number setting for abc.test.com
}
return 1;
}
}
Sample code of your ConfigureService
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpContextAccessor();
services.AddControllersWithViews();
services.AddSingleton<IMySettingServices, MySettingServices>();
services.AddOptions<MyAppSettings>().Configure<IMySettingServices>((setting, settingServices) => {
setting.FavouriteColor = settingServices.GetFavouriteColor();
setting.LuckNumber = settingServices.GetLuckNumber();
});//This is the key point of this answer, you are delegating your setting assignment to a services, so you can do whatever you want in your services, in your word, customise configuration binding
}
Sample code of use your configuration in controller
public class HomeController : Controller
{
private readonly ILogger<HomeController> _logger;
private readonly IOptions<MyAppSettings> settings;
public HomeController(ILogger<HomeController> logger, IOptions<MyAppSettings> settings)
{
_logger = logger;
this.settings = settings;
}
public IActionResult Index()
{
var favColor = settings.Value.FavouriteColor;
return View();
}
}
please be aware that when you want to access httpcontext, do not directly add services.AddScoped/AddSingleton/AddTransit<IHttpContextAccessor,HttpContextAccessor>(), this will result to DI system unable to resolve IHttpContextAccessor during ConfigureServices phases. Use services.AddHttpContextAccessor(); is the best way to do that
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>();
Just to add to the other answers...
In ASP.NET Core 2.1, there's the AddHttpContextAccessor extension method, that will register the IHttpContextAccessor with the correct lifetime:
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpContextAccessor();
// Other code...
}
}
According to this article: Accessing HttpContext outside of framework components in ASP.NET Core
namespace System.Web
{
public static class HttpContext
{
private static IHttpContextAccessor _contextAccessor;
public static Microsoft.AspNetCore.Http.HttpContext Current => _contextAccessor.HttpContext;
internal static void Configure(IHttpContextAccessor contextAccessor)
{
_contextAccessor = contextAccessor;
}
}
}
Then:
public static class StaticHttpContextExtensions
{
public static void AddHttpContextAccessor(this IServiceCollection services)
{
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}
public static IApplicationBuilder UseStaticHttpContext(this IApplicationBuilder app)
{
var httpContextAccessor = app.ApplicationServices.GetRequiredService<IHttpContextAccessor>();
System.Web.HttpContext.Configure(httpContextAccessor);
return app;
}
}
Then:
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpContextAccessor();
}
public void Configure(IApplicationBuilder app)
{
app.UseStaticHttpContext();
app.UseMvc();
}
}
You can use it like this:
using System.Web;
public class MyService
{
public void DoWork()
{
var context = HttpContext.Current;
// continue with context instance
}
}
In Startup
services.AddHttpContextAccessor();
In Controller
public class HomeController : Controller
{
private readonly IHttpContextAccessor _context;
public HomeController(IHttpContextAccessor context)
{
_context = context;
}
public IActionResult Index()
{
var context = _context.HttpContext.Request.Headers.ToList();
return View();
}
}
To access to the session object from a class without explicitly use dependency injection in class constructor follow the next steps:
Add a Singleton instance on Startup.cs (ConfigureServices):
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
In your target class declare an instance of HttpContextAccessor:
IHttpContextAccessor _httpContextAccessor = new HttpContextAccessor();
Access to the session object :
string mySessionVar = _httpContextAccessor.HttpContext.Session.GetString("_MySessionVar");
EXAMPLE
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}
YourClass.cs
public class YourClass {
public string yourProperty {
get{
IHttpContextAccessor _httpContextAccessor = new HttpContextAccessor();
return _httpContextAccessor.HttpContext.Session.GetString("_YourSessionVar");
}
}
}
Enjoy :)
I need to get HttpContext.Current and HostingEnvironment in a class EmployeeDataAccessLayer in AddEmployee function. I have written below code now I am facing a problem that how can I call/use the function AddEmployee in my controller.
Now, as I have created 2 new constructors with parameters IHttpContextAccessor and IHostingEnvironment respectively causing me problem, I am not getting a proper way to use it.
public class EmployeeDataAccessLayer
{
private readonly IHttpContextAccessor _httpContextAccessor;
private IHostingEnvironment _hostingEnvironment;
public EmployeeDataAccessLayer(IHttpContextAccessor httpContextAccessor)
{
_httpContextAccessor = httpContextAccessor;
}
public EmployeeDataAccessLayer(IHostingEnvironment environment)
{
_hostingEnvironment = environment;
}
public void AddEmployee(TblEmployee employee)
{
try
{
string folderName = "UploadFile/";
string sPath = "";
sPath = Path.Combine(_hostingEnvironment.WebRootPath, "~/" + folderName);
var hfc = _httpContextAccessor.HttpContext.Request.Form.Files;
}
I am following this article.
Most likely you haven't configured your controller to require an instance of EmployeeDataAccessLayer.
Be sure to register the EmployeeDataAccessLayer as a dependency like in the article you linked. Then your controller should take EmployeeDataAccessLayer as a constructor argument, you will store that as a readonly field and use it in your controller action. Then you should see that EmployeeDataAccessLayer has an instance of IHttpContextAccessor provided.
See a more complete example as the one you link is not complete(e.g. this one from microsoft).
As a side note, in your EmployeeDataAccessLayer you probably should not require the IHttpContext dependency if possible as others have mentioned in comments.
Try using interface as follows :
//controller
public class HomeController
{
private readonly IDataAccess _dataAccess;
public HomeController(IDataAccess dataAccess)
{
_dataAccess = dataAccess;
}
[HttpPost]
public ActionResult Index(TblEmployee employee)
{
_dataAccess.AddEmployee(employee);
return View();
}
}
// Startup
public void ConfigureServices(IServiceCollection services)
{
// add dependency
services.AddScoped<IDataAccess, EmployeeDataAccessLayer>();
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}
// Data Access Impl
public class EmployeeDataAccessLayer : IDataAccess
{
private readonly IHttpContextAccessor _httpContextAccessor;
private IHostingEnvironment _hostingEnvironment;
public EmployeeDataAccessLayer(IHttpContextAccessor httpContextAccessor)
{
_httpContextAccessor = httpContextAccessor;
}
public EmployeeDataAccessLayer(IHostingEnvironment environment)
{
_hostingEnvironment = environment;
}
public void AddEmployee(TblEmployee employee)
{
try
{
string folderName = "UploadFile/";
string sPath = "";
sPath = Path.Combine(_hostingEnvironment.WebRootPath, "~/" + folderName);
var hfc = _httpContextAccessor.HttpContext.Request.Form.Files;
catch{}
}
}
// interface
public interface IDataAccess
{
void AddEmployee(TblEmployee employee);
}
Another ugly approach (Using service locator):
if you don't want DI and constructor, you can use service locator as follows:
public static class MyServiceLocator
{
public static IServiceProvider Instance { get; set; }
}
public void Configure(IApplicationBuilder app)
{
MyServiceLocator.Instance = app.ApplicationServices;
}
// Data Access
public class EmployeeDataAccessLayer
{
public void AddEmployee(TblEmployee employee)
{
try
{
IHttpContextAccessor httpContextAccessor =MyServiceLocator.Instance.GetService<IHttpContextAccessor>();
IHostingEnvironment hostingEnvironment=MyServiceLocator.Instance.GetService<IHostingEnvironment>();;
string folderName = "UploadFile/";
string sPath = "";
sPath = Path.Combine(_hostingEnvironment.WebRootPath, "~/" + folderName);
var hfc = _httpContextAccessor.HttpContext.Request.Form.Files;
}
catch{}
}
}