I have two class which using nested dependency. My class are ExceptionHandler and JwtHelper. Startup.cs call ExceptionHandler. Then ExceptionHandler call JwtHelper. But while I getting exceptionHandler in startup.cs, it gave me error
Unable to resolve service for type 'Hsys.WebToken.JwtHelper' while attempting to activate 'Hsys.ExceptionHandling.ExceptionHandler'
I added dependencies to Startup.cs. What can be reason of this error?
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpContextAccessor();
services.AddSingleton<IJwtHelper, JwtHelper>();
services.AddSingleton<IExceptionHandler, ExceptionHandler>();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env, IHttpContextAccessor httpContextAccessor)
{
app.UseExceptionHandler(builder => builder.Run(async context =>
{
var error = context.Features.Get<IExceptionHandlerFeature>();
//This line give me error while Getting Required Service
IExceptionHandler exceptionHandler = app.ApplicationServices.GetRequiredService<IExceptionHandler>();
await exceptionHandler.AddApplicationError(context, error);
await context.Response.WriteAsync(error.Error.Message);
}));
app.UseHttpsRedirection();
app.UseMvc();
}
ExceptionHandler.cs
public class ExceptionHandler : IExceptionHandler
{
private readonly JwtHelper jwtHelper;
public ExceptionHandler(JwtHelper jwtHelper)
{
this.jwtHelper = jwtHelper;
}
public async Task AddApplicationError()
{
var userId = jwtHelper.GetValueFromToken("userId");
}
}
JwtHelper.cs
public class JwtHelper : IJwtHelper
{
private readonly IHttpContextAccessor httpContextAccessor;
public JwtHelper(IHttpContextAccessor httpContextAccessor)
{
this.httpContextAccessor = httpContextAccessor;
}
public string GetValueFromToken(string propertyName)
{
var handler = new JwtSecurityTokenHandler();
var tokens = handler.ReadToken(httpContextAccessor.HttpContext.Request.Headers["Authorization"]) as JwtSecurityToken;
return tokens.Claims.FirstOrDefault(claim => claim.Type == propertyName).Value;
}
}
You Registered IJwtHelper with the DI container, with a concrete class of JwtHelper. However inside your exception handler you are telling the DI container you want JwtHelper injected. You never registered JwtHelper, but its interface. You want your ExceptionHandler class to look like this instead.
public class ExceptionHandler : IExceptionHandler
{
private readonly IJwtHelper jwtHelper;
public ExceptionHandler(IJwtHelper jwtHelper)
{
this.jwtHelper = jwtHelper;
}
public async Task AddApplicationError()
{
var userId = jwtHelper.GetValueFromToken("userId");
}
}
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 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 am writing code for following: Access the current HttpContext in ASP.NET Core
I am receiving error. How would I resolve this?
Also, whats the code for Interface IMyComponent? Just want to be sure its correct.
Errors:
Type or namespace IMyComponent Cannot be found
The Name 'KEY' does not exist in current context.
public class MyComponent : IMyComponent
{
private readonly IHttpContextAccessor _contextAccessor;
public MyComponent(IHttpContextAccessor contextAccessor)
{
_contextAccessor = contextAccessor;
}
public string GetDataFromSession()
{
return _contextAccessor.HttpContext.Session.GetString(*KEY*);
}
}
Some points you need to pay attention to:
1.You class inherit from an interface and implement a GetDataFromSession method.You need to define an interface IMyComponent first and register IMyComponent in staryup if you would like use by DI
public interface IMyComponent
{
string GetDataFromSession();
}
startup.cs
services.AddSingleton<IMyComponent, MyComponent>();
2.It seems that you would like to get data from session. The "Key" represents any session name (string).You need to enable session for asp.net core and set a session value first.
_contextAccessor.HttpContext.Session.SetString("Key", "value");
3.Register IHttpContextAccessor in your startup
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
4.Full demo:
MyComponent.cs
public class MyComponent : IMyComponent
{
private readonly IHttpContextAccessor _contextAccessor;
public MyComponent(IHttpContextAccessor contextAccessor)
{
_contextAccessor = contextAccessor;
}
public string GetDataFromSession()
{
_contextAccessor.HttpContext.Session.SetString("Key", "value");
return _contextAccessor.HttpContext.Session.GetString("Key");
}
}
public interface IMyComponent
{
string GetDataFromSession();
}
Startup.cs:
public void ConfigureServices(IServiceCollection services)
{
services.AddDistributedMemoryCache();
services.AddSession(options =>
{
// Set a short timeout for easy testing.
options.IdleTimeout = TimeSpan.FromSeconds(10);
options.Cookie.HttpOnly = true;
// Make the session cookie essential
options.Cookie.IsEssential = true;
});
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddScoped<IMyComponent, MyComponent>();
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
//other middlewares
app.UseSession();
app.UseMvc();
}
}
API Controller:
public class ForumsController : ControllerBase
{
private readonly IMyComponent _myComponent;
public ForumsController(IMyComponent myComponent)
{
_myComponent = myComponent;
}
// GET api/forums
[HttpGet]
public ActionResult<string> Get()
{
var data = _myComponent.GetDataFromSession();//call method and return "value"
return data;
}
I am building a web application where I will have a lot of controllers with their corresponding action methods in them.
I want to save every exception in database and for this reason I have created
ExceptionService (DbContext is injected in it).
let's say that this is the general form of my controllers:
[Route("api/[controller]")]
[ApiController]
public class UserController : ControllerBase
{
private readonly UserManager userManager;
private readonly IExceptionService exceptionService;
public UserController(UserManager userManager, IExceptionService exceptionService)
{
this.userManager = userManager;
this.exceptionService = exceptionService;
}
[HttpPost]
public async Task<IActionResult> Post([FromBody] User user)
{
try
{
//some code
}
catch (Exception e)
{
exceptionService.Save(e);
//some code
}
}
}
In order to avoid so many try-catch blocks I decided to create a filter which looks like this:
public class ApiExceptionFilterAttribute : ExceptionFilterAttribute
{
private readonly IExceptionService exceptionService;
public ApiExceptionFilterAttribute(IExceptionService exceptionService)
{
this.exceptionService = exceptionService;
}
public override void OnException(ExceptionContext context)
{
Exception e = context.Exception;
exceptionService.Save(e);
//some code
}
}
Code in ConfigureServices method in StartUp.cs looks like this (some code removed for simplicity):
services
.AddMvc()
.SetCompatibilityVersion(CompatibilityVersion.Version_2_1)
.AddJsonOptions(options => options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore);
services
.AddDbContext<AppDbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("Default")));
services.AddScoped<UserManager>();
services.AddScoped<SignInManager>();
services.AddScoped<IExceptionService, ExceptionService>();
services.AddSingleton<IConfigureOptions<MvcOptions>, ConfigureMvcOptions>();
ConfgureMvcOptions class looks like this:
public class ConfigureMvcOptions : IConfigureOptions<MvcOptions>
{
private readonly IExceptionService exceptionService;
public ConfigureMvcOptions(IExceptionService exceptionService)
{
this.exceptionService = exceptionService;
}
public void Configure(MvcOptions options)
{
options.Filters.Add(new ApiExceptionFilterAttribute(exceptionService));
}
}
When I run this application, I get the following error:
System.InvalidOperationException: 'Cannot consume scoped service 'SmartWay.Services.IExceptionService' from singleton 'Microsoft.Extensions.Options.IConfigureOptions`1[Microsoft.AspNetCore.Mvc.MvcOptions]'.'
If I change IExceptionServcise's lifetime to transient than I have to do so for
Dbcontext, then for DbContextOptions... It seems that it isn't right way..
So, How can I solve this problem?
For resolving scoped service from singleton service, try _serviceProvider.CreateScope.
Follow steps below:
ExceptionService
public interface IExceptionService
{
void Save(Exception ex);
}
public class ExceptionService : IExceptionService
{
private readonly IServiceProvider _serviceProvider;
public ExceptionService(IServiceProvider serviceProvider)
{
_serviceProvider = serviceProvider;
}
public void Save(Exception ex)
{
using (var scope = _serviceProvider.CreateScope())
{
var _context = scope.ServiceProvider.GetRequiredService<MVCProContext>();
_context.Add(new Book() { Title = ex.Message });
_context.SaveChanges();
}
}
}
Startup.cs
services.AddSingleton<IExceptionService, ExceptionService>();
services.AddSingleton<IConfigureOptions<MvcOptions>, ConfigureMvcOptions>();
I want to access JwtHelper from ExceptionHelper. But problem is ExceptionHelper must be static. And so, we can't create constructor and not access jwtHelper Method. How can I achieve access jwHelper from ExcewptionHelper.
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpContextAccessor();
services.AddMvc();
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddDbContext<MyDbContext>();
services.AddTransient<IUnitOfWork, UnitOfWork>();
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseExceptionHandler(builder => builder.Run(async context =>
{
var error = context.Features.Get<IExceptionHandlerFeature>();
context.Response.AddApplicationError(error);
await context.Response.WriteAsync(error.Error.Message);
}));
app.UseHttpsRedirection();
app.UseMvc();
}
ExceptionHelper.cs
public static class ExceptionHelper
{
public static async Task AddApplicationError(this HttpResponse response)
{
Log log = new Log();
log.UserId = jwtHelper.GetValueFromToken(token, "UserId");??????
//in this line I can't access jwtHelper.
}
}
JwtHelper.cs
public class JwtHelper : IJwtHelper
{
private readonly IHttpContextAccessor httpContextAccessor;
public JwtHelper(IHttpContextAccessor httpContextAccessor)
{
this.httpContextAccessor = httpContextAccessor;
}
public string GetValueFromToken(string stream, string propertyName)
{
var jwt = httpContextAccessor.HttpContext.Request.Headers["Authorization"];
var handler = new JwtSecurityTokenHandler();
var tokens = handler.ReadToken(stream.Replace("Bearer ", "")) as JwtSecurityToken;
return tokens.Claims.FirstOrDefault(claim => claim.Type == propertyName).Value;
}
}
If I were you I would register JwtHelper with a Interface known as IJwtHelper.
It would look like this then
public class JwtHelper : IJwtHelper
{
private readonly IHttpContextAccessor httpContextAccessor;
public JwtHelper(IHttpContextAccessor httpContextAccessor)
{
this.httpContextAccessor = httpContextAccessor;
}
public string GetValueFromToken(string propertyName)
{
var jwt= httpContextAccessor.HttpContext.Request.Headers["Authorization"];
// I can't access httpContextAccessor in this line.
var handler = new JwtSecurityTokenHandler();
var tokens = handler.ReadToken(jwt) as JwtSecurityToken;
return tokens.Claims.FirstOrDefault(claim => claim.Type == propertyName).Value;
}
}
public interface IJwtHelper
{
string GetValueFromToken(string propertyName);
}
In my startup.cs class I would then do
services.AddSingleton<IJwtHelper, JwtHelper>();
And then when you want to access your helper I would inject IJwtHelper
private IJwtHelper _jwtHelper;
public SomeConstructerOnClass(IJwtHelper jwtHelper)
{
_jwtHelper = jwtHelper;
}
public void SomeMethod(string property) {
var token = _jwtHelper.GetValueFromToken(property);
//Do something with token
}
where _jwtHelper is field of type IJwtHelper.
You will then be able to use GetValueFromToken quite fine anywhere you inject IJwtHelper
UPDATE
Your problem is that ExceptionHandler is Static , implement an interface and add it to container
public class ExceptionHelper : IExceptionHelper
{
private IJwtHelper _jwtHelper;
public ExceptionHelper(IJwtHelper jwtHelper)
{
_jwtHelper = jwtHelper;
}
public async Task AddApplicationError(this HttpResponse response)
{
Log log = new Log();
log.UserId = _jwtHelper.GetValueFromToken(token, "UserId");??????
}
}
public interface IExceptionHelper
{
Task AddApplicationError( HttpResponse response);
}
Then
services.AddSingleton<IExceptionHelper, ExceptionHelper>();
Now You will be able to inject it into your Configure method like so
public void Configure(IApplicationBuilder app, IHostingEnvironment env, IExceptionHelper exceptionHelper)
{
app.UseExceptionHandler(builder => builder.Run(async context =>
{
var error = context.Features.Get<IExceptionHandlerFeature>();
//Resolved and available!
exceptionHelper.AddApplicationError(error);
await context.Response.WriteAsync(error.Error.Message);
}));
app.UseHttpsRedirection();
app.UseMvc();
}
If you follow me advice above from my initial response and my update everything should be fine and registered nicely in your container :)
You'll have to instantiate the JwtHelper class in order to access the instance variable (httpContextAccessor) from another class. Static methods, like GetValueFromToken, cannot access instance variables.