I'm setting a transient attribute in the screen controller using a service to retrieve the information I need (which is a list of instances that need the attribute to be set). The problem is that after using a filter, the transient attribute reset. Is it expected? Is there a listener to be used after a filter is applied?
Yes, there is such listener:
#Inject
private Filter filter;
#Override
public void init(Map<String, Object> params) {
filter.setAfterFilterAppliedHandler(() -> {
});
}
Related
When getting a request in any action of any controller, I look at the jwt know which user is requesting and lookup the user in the database to get some user-data that I want to use throughout the application. E.g. which departments the user belongs to or the users preferred language.
Now I could create a object which wraps these information and send it down the layers and pass it to every method that likes to use some of this data. But I like the data to be available to every method throughout the application without passing it in every method. Like e.g. dependency injection (Seems to late at that point) or something else I can get access to that data quickly.
Any advice of how to handle it?
Try it with the Items property on the HttpContext. By using it you can store data during a single request. The only downside with this approach is that every service needs to have access to the HttpContext to read the values. Values can be added to the Items Dictionary as shown below
public class IndexModel : PageModel
{
//
public void OnGet()
{
HttpContext.Items.Add("Key", new RequestInfo { Key = "RequestKey" });
}
}
class RequestInfo
{
public string Key { get; set; }
}
You can then access the value by registering the IHttpContextAccessor to the IServiceCollection and then using Constructor injection to use the HttpContext in your service so that you can work with the Items Dictionary.
public class Service
{
private IHttpContextAccessor _htp;
public Service(IHttpContextAccessor http)
{
_htp = http;
}
public void Log()
{
Console.WriteLine(((RequestInfo)_htp.HttpContext.Items["Key"]).Key);
}
}
I am trying to inject a service into my action filter but I am not getting the required service injected in the constructor. Here is what I have:
public class EnsureUserLoggedIn : ActionFilterAttribute
{
private readonly ISessionService _sessionService;
public EnsureUserLoggedIn()
{
// I was unable able to remove the default ctor
// because of compilation error while using the
// attribute in my controller
}
public EnsureUserLoggedIn(ISessionService sessionService)
{
_sessionService = sessionService;
}
public override void OnActionExecuting(ActionExecutingContext context)
{
// Problem: _sessionService is null here
if (_sessionService.LoggedInUser == null)
{
context.HttpContext.Response.StatusCode = (int)HttpStatusCode.Unauthorized;
context.Result = new JsonResult("Unauthorized");
}
}
}
And I am decorating my controller like so:
[Route("api/issues"), EnsureUserLoggedIn]
public class IssueController : Controller
{
}
Startup.cs
services.AddScoped<ISessionService, SessionService>();
Using these articles as reference:
ASP.NET Core Action Filters
Action filters, service filters and type filters in ASP.NET 5 and MVC 6
Using the filter as a ServiceFilter
Because the filter will be used as a ServiceType, it needs to be registered with the framework IoC. If the action filters were used directly, this would not be required.
Startup.cs
public void ConfigureServices(IServiceCollection services) {
services.AddMvc();
services.AddScoped<ISessionService, SessionService>();
services.AddScoped<EnsureUserLoggedIn>();
...
}
Custom filters are added to the MVC controller method and the controller class using the ServiceFilter attribute like so:
[ServiceFilter(typeof(EnsureUserLoggedIn))]
[Route("api/issues")]
public class IssueController : Controller {
// GET: api/issues
[HttpGet]
[ServiceFilter(typeof(EnsureUserLoggedIn))]
public IEnumerable<string> Get(){...}
}
There were other examples of
Using the filter as a global filter
Using the filter with base controllers
Using the filter with an order
Take a look, give them a try and see if that resolves your issue.
Hope this helps.
Global filters
You need to implement IFilterFactory:
public class AuthorizationFilterFactory : IFilterFactory
{
public bool IsReusable => false;
public IFilterMetadata CreateInstance(IServiceProvider serviceProvider)
{
// manually find and inject necessary dependencies.
var context = (IMyContext)serviceProvider.GetService(typeof(IMyContext));
return new AuthorizationFilter(context);
}
}
In Startup class instead of registering an actual filter you register your filter factory:
services.AddMvc(options =>
{
options.Filters.Add(new AuthorizationFilterFactory());
});
One more way for resolving this problem. You can get your service via Context as in the following code:
public override void OnActionExecuting(ActionExecutingContext context)
{
_sessionService = context.HttpContext.RequestServices.GetService<ISessionService>();
if (_sessionService.LoggedInUser == null)
{
context.HttpContext.Response.StatusCode = (int)HttpStatusCode.Unauthorized;
context.Result = new JsonResult("Unauthorized");
}
}
Please note that you have to register this service in Startup.cs
services.AddTransient<ISessionService, SessionService>();
Example
private ILoginService _loginService;
public override void OnActionExecuting(ActionExecutingContext context)
{
_loginService = (ILoginService)context.HttpContext.RequestServices.GetService(typeof(ILoginService));
}
Hope it helps.
After reading this article ASP.NET Core - Real-World ASP.NET Core MVC Filters (Aug 2016) I implemented it like this:
In Starup.cs / ConfigureServices:
services.AddScoped<MyService>();
In MyFilterAttribute.cs:
public class MyFilterAttribute : TypeFilterAttribute
{
public MyFilterAttribute() : base(typeof (MyFilterAttributeImpl))
{
}
private class MyFilterAttributeImpl : IActionFilter
{
private readonly MyService _sv;
public MyFilterAttributeImpl(MyService sv)
{
_sv = sv;
}
public void OnActionExecuting(ActionExecutingContext context)
{
_sv.MyServiceMethod1();
}
public void OnActionExecuted(ActionExecutedContext context)
{
_sv.MyServiceMethod2();
}
}
}
In MyFooController.cs :
[MyFilter]
public IActionResult MyAction()
{
}
Edit: Passing arguments like [MyFilter("Something")] can be done using the Arguments property of the TypeFilterAttribute class: How do I add a parameter to an action filter in asp.net? (rboe's code also shows how to inject things (the same way))
While the question implicitly refers to "filters via attributes", it is still worth highlighting that adding filters "globally by type" supports DI out-of-the-box:
[For global filters added by type] any constructor dependencies will be populated by dependency injection (DI). Adding a filter by type is equivalent to filters.Add(new TypeFilterAttribute(typeof(MyFilter))).
https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/filters?view=aspnetcore-2.2#dependency-injection
With regards to attribute-based filters:
Filters that are implemented as attributes and added directly to controller classes or action methods cannot have constructor dependencies provided by dependency injection (DI). This is because attributes must have their constructor parameters supplied where they're applied. This is a limitation of how attributes work.
https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/filters?view=aspnetcore-2.2#dependency-injection
However, as mentioned in the previous answers to the OP, there are ways of indirection that can be used to achieve DI. For the sake of completeness, here are the links to the official docs:
ServiceFilterAttribute
TypeFilterAttribute
IFilterFactory implemented on your attribute
I have next event handler:
#Component
#RepositoryEventHandler
public class EntityEventHandler {
private final EntityService entityService;
#HandleAfterSave
public void handleAfterSave(final Entity entity) {
// need old entity here to validate if specific field has changed
}
}
Is there any way to get old entity in handleAfterSave ?
I use unity and then ninject in mvc4, mvc5.
I inject service or dbcontext to action filter as public property this way:
public class MyActionFilterAttribute: FilterAttribute,IActionFilter
{
[Inject]
public IDbContext DbContext { get; set; }
[Inject]
public IProductService ProductService { get; set; }
public void OnActionExecuting(ActionExecutingContext filterContext)
{
Debug.WriteIf(DbContext == null, "db context is null");
Debug.WriteIf(ProductService == null, "productservice is null");
}
public void OnActionExecuted(ActionExecutedContext filterContext)
{ }
}
}
If I register a global filter, filters.Add(new MyActionFilterAttribute()); DbContext and ProductService are always null.
But if i mark [MyActionFilter] attribute to Controller everything works fine.
I'd like to register some filter as global, please help.
Wen you are registering global filters like this filters.Add(new MyActionFilterAttribute()); you are registering filter instance. This same instance will be used on every call. This instance doesn't have your dependencies populated because you created it yourself using default constructor instead of resolving it from the container. Of course you cant resolve instance of your filter during global filter registration because your dependencies (DbContext for example) need to be scoped per request.
So you have 4 options.
Decorate all your controllers with the action filter
Create controller base class, decorate this class with the action filter and then derive all your controllers from this class.
Use some form of service locator inside your action filter code to resolve your dependencies from the container every time they are needed. Then you can register your filter as a global filter.
Create custom IFilterProvider and resolve your filter from the container in the GetFilters method. Then register your provider FilterProviders.Providers.Add(new MyFilterProvider(diContainer));
The simple example is to register your filter globally in the NinjectWebCommon class, you can do like this:
kernel.BindFilter<MyActionFilterAttribute>(FilterScope.Global, 1).InRequestScope();
and remove the line from Global.asax
I'm migrating code from NSBv4 to NSBv5 (5.2.12 to be exact) and I have a custom profile implementation:
public class MyProfileHandler : IHandleProfile<PerformanceCounters>
{
public MyProfileHandler()
{
}
public void ProfileActivated(BusConfiguration config)
{
// I need to do something based on endpoint configuration, e.g. endpoint name
// this used to work in NSBv4:
// var endpointName = Configure.EndpointName;
}
}
How can I access endpoint configuration here?
I'm hosting this app using NServiceBus.Host (v6.0.0 if it matters) and this is where the IHandleProfile<T> interface comes from.
BusConfiguration is a configuration builder and it seems it's not possible to read anything useful from it. I tried to inject an instance of Configure to the constructor of my profile handler, but then it crashes - NSB needs the handler to have a parameterless constructor.
Implementing IWantTheEndpointConfig is not an option as well, as it is deprecated in v5 and it causes a compilation error. Its obsolete error message states:
IHandleProfile is now passed an instance of Configure
(which would be perfect for my case), but this is not true as far as I can tell (there is no Configure passed to ProfileActivated() and I can't see how I can inject it).
Is my only option to reimplement the profile handler using a completely different approach, or am I missing something?
NServiceBus.Core has an issue how it sets the endpoint name (and unfortunately also the endpoint version) on the BusConfiguration. The set endpoint name is added to the settings dictionary too late. You can work around that issue by doing the following:
public class EndpointConfig : IConfigureThisEndpoint
{
public void Customize(BusConfiguration configuration)
{
var customConfig = new EndpointConfiguration
{
EndpointName = "YourEndpointName",
};
configuration.EndpointName(customConfig.EndpointName);
configuration.GetSettings().Set<EndpointConfiguration>(customConfig);
}
}
public class EndpointConfiguration
{
public string EndpointName { get; set; }
}
BusConfiguration is essentially a dictionary on steroids. If you want to get access to what has been set in the BusConfiguration in the profile handler you can do the following (i.ex. get the endpoint name):
public class MyProfileHandler : IHandleProfile<PerformanceCounters>
{
public void ProfileActivated(BusConfiguration config)
{
var customConfig = config.GetSettings().Get<EndpointConfiguration>();
var endpointName = customConfig.EndpointName;
}
}
In the normal NServiceBus Host the interface offers only the one parameter, BusConfiguration. On Azure the interface offers two methods, where one actually has the Configure object.