I'm migrating an application from Ninject to Autofac.
We used a special naming convention for injecting app settings into constructors:
public class Example{
public Example(AppSetting settingName){
...
}
}
AppSetting parameter was injected automatically using ConfigurationManager.AppSettings["settingName"].
In Ninject this was accomplished by using a custom provider:
public class AppSettingProvider : Ninject.Activation.IProvider
{
public object Create(IContext context)
{
var varName = ((Context)context).Request.Target.Name;
var value = new AppSetting(ConfigurationManager.AppSettings[varName]);
if (value.Value == null)
{
... log ...
}
return value;
}
public Type Type
{
get { return typeof(AppSetting); }
}
}
I was not able to find an alternative for this feature in Autofac. If this is not possible in an automated way I'm ok with looping over all app settings during the initial configuration step.
Any idea what to do?
Thanks,
Vilem
I have created a solution using this SO question:
Register string value for concrete name of parameter
and subsequently improved it using Travis Illig's suggestion.
Currently this seems to work exactly the same as the Ninject equivalent.
Here's the result:
public class AppSettingsModule : Module
{
protected override void AttachToComponentRegistration(
IComponentRegistry componentRegistry,
IComponentRegistration registration)
{
// Any time a component is resolved, it goes through Preparing
registration.Preparing += InjectAppSettingParameters;
}
private void InjectAppSettingParameters(object sender, PreparingEventArgs e)
{
// check if parameter is of type AppSetting and if it is return AppSetting using the parameter name
var appSettingParameter = new ResolvedParameter((par, ctx) => par.ParameterType == typeof(AppSetting), (par, ctx) => new AppSetting(ConfigurationManager.AppSettings[par.Name]));
e.Parameters = e.Parameters.Union(new List<Parameter>{ appSettingParameter});
}
}
Related
I have a Web project and a Windows Service project in my solution. I have created 2 different binding modules for these 2 projects, but as you can see it has a lot of duplicate code... the only difference is that I am using InRequestScope() for the Web project and InTransientScope() for Windows Service project.
Is it possible combine the bindings, and add the scope depending on the project/entry point?
public class WebModule : NinjectModule
{
public override void Load()
{
Bind<ApplicationDbContext>().ToSelf().InRequestScope();
Bind<IMyRepository>().To<MyRepository>().InRequestScope();
// more types ... InRequetScope();
}
}
public class ServiceModule : NinjectModule
{
public override void Load()
{
Bind<ApplicationDbContext>().ToSelf().InTransientScope();
Bind<IMyRepository>().To<MyRepository>().InTransientScope();
// more types ... InTransientScope();
}
}
Update:
As explained by ninject team, we can use InRequestScope() in both scenarios... since there is no concept of Request in a Windows Service project, ninject would use the default scope, which is InTransientScope() in the service project.
Original Answer
The best solution that I have come up with is to create an extension method:
public static class NinjectExtensions
{
public static IBindingNamedWithOrOnSyntax<T> GetScopeByName<T>(this IBindingInSyntax<T> syntax, string scope)
{
if (scope.Equals("request", StringComparison.InvariantCultureIgnoreCase))
{
return syntax.InRequestScope();
}
else if (scope.Equals("thread", StringComparison.InvariantCultureIgnoreCase))
{
return syntax.InThreadScope();
}
else if (scope.Equals("singleton", StringComparison.InvariantCultureIgnoreCase))
{
return syntax.InSingletonScope();
}
return syntax.InTransientScope();
}
}
And set the scope dynamically.
public class MyModule : NinjectModule
{
private string _scope = "transient";
public MyModule()
{
if (Convert.ToBoolean(ConfigurationManager.AppSettings["IsWebProject"]))
{
_scope = "request";
}
}
public override void Load()
{
Bind<ApplicationDbContext>().ToSelf().GetScopeByName(_scope);
Bind<IMyRepository>().To<MyRepository>().GetScopeByName(_scope);
// more types ... InRequetScope();
}
}
Note: I am not sure if there is a better solution... this is just the cleanest approach that has come to my mind.
I want to inject some ValueType variable values using autofac, as we do same for Interfaces. I don't want to additionally mention in bootstrapper that this class have named parameterized injection or with Key.
For eg: This is easily injectable
Registration =>
builder.RegisterType<SqlProvider>().As<ISqlProvider>();
Injection=>
MyClass(ISqlProvider provider)
So Can we do something like:
Registration =>
builder.RegisterType<int>().Named<int>("maxRetries");
Injection=>
MyClass(int maxRetries)
I think what you need is property injection.
http://autofac.readthedocs.io/en/latest/register/prop-method-injection.html
You could for the sake of simplicity use a factory or settingsprovider just like your sqlprovider.
Because i think you want to create some servicelayer.
Pseudocode:
private iSqlProvider _sqlprovider;
private ISettingsProvider _settingsProvider;
MyClass(ISqlProvider sqlprovider, ISettingProvider settingProvider)
{
_sqlprovider = sqlprovider;
_settingsProvider = settingsProvider
}
public MyClassModel GetMyAwesomeModels()
{
var settings = _setingsprovider.getSetting()
settings.maxTries
//do your magic with maxtries
}
You can use a custom parameter and a module to have this feature.
A module allows you to add custom parameter for every registration. A parameter is a special class that Autofac will call each time a registration is resolved to check whether it can provide the requested parameter.
For example :
public class ResolvedNamedParameter : Parameter
{
public override Boolean CanSupplyValue(ParameterInfo pi,
IComponentContext context,
out Func<Object> valueProvider)
{
if (pi.ParameterType.IsValueType
&& context.IsRegisteredWithName(pi.Name, pi.ParameterType))
{
valueProvider = () => context.ResolveNamed(pi.Name, pi.ParameterType);
return true;
}
else
{
valueProvider = null;
return false;
}
}
}
Then the module to add the parameter for every registration :
public class ResolvedNamedParameterModule : Module
{
protected override void AttachToComponentRegistration(IComponentRegistry componentRegistry,
IComponentRegistration registration)
{
registration.Preparing += (sender, e) =>
{
e.Parameters = new Parameter[] { new ResolvedNamedParameter() }.Concat(e.Parameters);
};
base.AttachToComponentRegistration(componentRegistry, registration);
}
}
And you can use it like this :
builder.RegisterModule<ResolvedNamedParameterModule>();
builder.Register(c => 3).Named<Int32>("x");
builder.Register(c => 5).Named<Int32>("y");
Try this:
Injection=>
MyClass([KeyFilter("maxRetries")]int maxRetries)
Is that what you were looking for?
I have this CacheAttribute that accepts Duration Value like such
public class MyTestQuery : IMyTestQuery
{
private readonly ISomeRepository _someRepository;
public TestQuery(ISomeRepository someRepository)
{
_someRepository = someRepository;
}
[Cache(Duration = 10)]
public MyViewModel GetForeignKeysViewModelCache()
{
...code here...
return viewModel;
}
}
The Attribute looks like this
[AttributeUsage(AttributeTargets.Method)]
public class CacheAttribute : Attribute
{
public int Duration { get; set; }
}
When Intercepted using Castle.Proxy.IInterceptor it works but when I perform an Attribute.GetCustomAttribute either by IInvocation.MethodInvocationTarget or IInvocation.Method both returns a null value
Here it is in code
public class CacheResultInterceptor : IInterceptor
{
public CacheAttribute GetCacheResultAttribute(IInvocation invocation)
{
var methodInfo = invocation.MethodInvocationTarget;
if (methodInfo == null)
{
methodInfo = invocation.Method;
}
return Attribute.GetCustomAttribute(
methodInfo,
typeof(CacheAttribute),
true
)
as CacheAttribute;
}
public void Intercept(IInvocation invocation)
{
var cacheAttribute = GetCacheResultAttribute(invocation);
//cacheAttribute is null always
...more code here...
}
}
And this is how I register them
public class Bootstrapper
{
public static ContainerBuilder Builder;
public static void Initialise()
{
Builder = new ContainerBuilder();
...other codes in here...
CacheInstaller.Install();
var container = Builder.Build();
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
}
}
public class CacheInstaller
{
public static void Install()
{
Bootstrapper.Builder.RegisterType<CacheResultInterceptor>()
.SingleInstance();
Bootstrapper.Builder.RegisterAssemblyTypes(Assembly.Load("MyApplication.Web"))
.Where(t => t.Name.EndsWith("Query"))
.AsImplementedInterfaces()
.EnableInterfaceInterceptors()
.InterceptedBy(typeof(CacheResultInterceptor))
.SingleInstance();
}
}
My Expensive Method Class Ends with Query
Now the question is why invocation.MethodInvocationTarget and/or invocation.Method returns null?
What am I doing wrong?
Any other strategies so I can pass a parameter value without creating a Method for each value I can think of?
BTW I am using
Autofac 4.3.0.0
Autofac.Extras.DynamicProxy 4.2.1.0
Autofac.Integration.Mvc 4.0.0.0
Castle.Core 4.0.0.0
UPDATE 1
Here is what it returns when it runs for clarity
Here's what I found.
invocation.Method returns the method declaration on the interface, in your case IMyTestQuery.
On the other hand, invocation.MethodInvocationProxy returns the method that is going to be called when invoking invocation.Proceed(). This means it can be:
the next interceptor if you have several
a decorator if you have decorators over your interface
the final implementation of your interface
As you can see, MethodInvocationProxy is less deterministic than Method, which is why I would recommend you avoid using it, at least for what you're trying to achieve.
When you think about it, an interceptor should not be tied to an implementation as it proxies an interface, so why don't you put the [Cache] attribute at the interface level?
Using your code, I could successfully retrieve it when put on the interface.
Edit:
OK, I've put together a repository on GitHub that uses the specific versions of the NuGet packages you mentioned and shows how to retrieve an attribute on intercepted methods.
As a reminder, here are the used NuGet packages:
Microsoft.AspNet.Mvc v5.2.3
Autofac v4.3.0
Autofac.Mvc5 4.0.0
Autofac.Extras.DynamicProxy v4.2.1
Castle.Core v4.0.0
I created 2 query interfaces, IMyQuery and IMySecondQuery. Please note that as mentioned in my original answer, the [Cache] attributes are placed on the interfaces methods, not on the implementing classes.
public interface IMyQuery
{
[Cache(60000)]
string GetName();
}
public interface IMySecondQuery
{
[Cache(1000)]
string GetSecondName();
}
Then we have 2 very basic implementations of these classes. Not relevant at all, but for the sake of completeness:
public class DefaultMyQuery : IMyQuery
{
public string GetName()
{
return "Raymund";
}
}
public class DefaultMySecondQuery : IMySecondQuery
{
public string GetSecondName()
{
return "Mickaël Derriey";
}
}
And then the interceptor:
public class CacheResultInterceptor : IInterceptor
{
public void Intercept(IInvocation invocation)
{
var cacheAttribute = invocation.Method.GetCustomAttribute<CacheAttribute>();
if (cacheAttribute != null)
{
Trace.WriteLine($"Found a [Cache] attribute on the {invocation.Method.Name} method with a duration of {cacheAttribute.Duration}.");
}
invocation.Proceed();
}
}
Note that the GetCustomAttribute<T> method is an extension method over MemberInfo present in the System.Reflection namespace.
Let's move on to the registration in the Autofac container. I tried to follow you registration style as much as I could:
var builder = new ContainerBuilder();
builder.RegisterControllers(typeof(MvcApplication).Assembly);
builder
.RegisterType<CacheResultInterceptor>()
.SingleInstance();
builder
.RegisterAssemblyTypes(typeof(MvcApplication).Assembly)
.Where(x => x.Name.EndsWith("Query"))
.AsImplementedInterfaces()
.EnableInterfaceInterceptors()
.InterceptedBy(typeof(CacheResultInterceptor));
DependencyResolver.SetResolver(new AutofacDependencyResolver(builder.Build()));
The queries are then used in the HomeController:
public class HomeController : Controller
{
private readonly IMyQuery _myQuery;
private readonly IMySecondQuery _mySecondQuery;
public HomeController(IMyQuery myQuery, IMySecondQuery mySecondQuery)
{
_myQuery = myQuery;
_mySecondQuery = mySecondQuery;
}
public ActionResult MyQuery()
{
return Json(_myQuery.GetName(), JsonRequestBehavior.AllowGet);
}
public ActionResult MySecondQuery()
{
return Json(_mySecondQuery.GetSecondName(), JsonRequestBehavior.AllowGet);
}
}
What I did to test this is just put a breakpoint in the interceptor, F5 the application, open a browser and navigate to both http://localhost:62440/home/myquery and http://localhost:62440/home/myquery.
It did hit the interceptor and find the [Cache] attribute. In the Visual Studio Output window, it did show:
Found a [Cache] attribute on the GetName method with a duration of 60000.
Found a [Cache] attribute on the GetSecondName method with a duration of 1000.
Hopefully that helps you pinpoint what's going on in your project.
I pushed changes to the repository so that the first query calls the second one.
It still works. You should really make an effort and put some code on the question.
I'm trying to inject a service using the IoC container into a Validation class. See the example below:
[Validator(typeof(UserPayloadValidator))]
public class UserPayload
{
public int UserId { get; set; }
}
public class UserPayloadValidator : AbstractValidator<UserPayload>
{
private IUserService _userService;
public UserPayloadValidator(IUserService userService)
{
_userService = userService;
RuleFor(x => x.UserId).Must(BeUnique).WithMessage("This user already exists");
}
private bool BeUnique(int userId)
{
var user = _userService.GetUser(userId);
return user == null;
}
}
At this point I was hoping everything would auto-magically work and the userService would be injected into the validation class. Instead, I get an exception complaining about a parameter-less constructor not being found.
After some reasearch I've attempted to create a ValidationFactory as in the example linked.
public class LightInjectValidationFactory : ValidatorFactoryBase
{
private readonly ServiceContainer _serviceContainer;
public LightInjectValidationFactory(ServiceContainer serviceContainer)
{
_serviceContainer = serviceContainer;
}
public override IValidator CreateInstance(Type validatorType)
{
return _serviceContainer.TryGetInstance(validatorType) as IValidator;
}
}
and in the LightInject configuration
//Set up fluent validation
FluentValidationModelValidatorProvider.Configure(httpConfiguration, provider =>
{
provider.ValidatorFactory = new LightInjectValidationFactory(container);
});
This results in an exception:
Unable to resolve type: FluentValidation.IValidator`1
I guess the IoC container doesn't know how to resolve the correct instance for the validator.
Any ideas are much appreciated.
Thanks to the comment above I realized I wasn't actually registering the validator in container. This can be done like this for all the validators:
FluentValidation.AssemblyScanner.FindValidatorsInAssemblyContaining<UserPayloadValidator>()
.ForEach(result =>
{
container.Register(result.InterfaceType, result.ValidatorType);
});
Please note that UserPayloadValidator needs to be just one of your validators. Based on this type, FindValidatorsInAssembly can infer all the other available validators.
Also, in the validation factory you should use TryGetInstance instead of GetInstance in case the factory tries to instantiate non existant validators (parameter in the controller for which validators do not exist)
I have found solution for all validation classes use injected service.
Replace below code
FluentValidation.AssemblyScanner.FindValidatorsInAssemblyContaining<UserPayloadValidator>()
.ForEach(result =>
{
container.Register(result.InterfaceType, result.ValidatorType);
});
With
FluentValidation.AssemblyScanner findValidatorsInAssembly = FluentValidation.AssemblyScanner.FindValidatorsInAssembly(typeof(UserPayloadValidator).Assembly);
foreach (FluentValidation.AssemblyScanner.AssemblyScanResult item in findValidatorsInAssembly)
{
container.Register(item.InterfaceType, item.ValidatorType);
}
Using this your all validator classes use injected service.
I am trying to create a custom resolver for automapper which needs to access one of my data repositories to retreive the logged in users account.
Here is my code so far...
public class FollowingResolver : ValueResolver<Audio, bool>
{
readonly IIdentityTasks identityTasks;
public FollowingResolver(IIdentityTasks identitTasks)
{
this.identityTasks = identitTasks;
}
protected override bool ResolveCore(Audio source)
{
var user = identityTasks.GetCurrentIdentity();
if (user != null)
return user.IsFollowingUser(source.DJAccount);
return false;
}
}
However I am getting this error:
FollowingResolver' does not have a default constructor
I have tried adding a default contrstructor but my repository never gets initialised then.
This is my autoampper initialisation code:
public static void Configure(IWindsorContainer container)
{
Mapper.Reset();
Mapper.Initialize(x =>
{
x.AddProfile<AccountProfile>();
x.AddProfile<AudioProfile>();
x.ConstructServicesUsing(container.Resolve);
});
Mapper.AssertConfigurationIsValid();
}
Am I missing something, is it even possible to do it like this or am I missing the boat here?
Found the solution shorlty after...i was forgetting to add my resolvers as an IoC container.
Works great now!
I was getting the same error using Castle Windsor while trying to inject a service.
I had to add:
Mapper.Initialize(map =>
{
map.ConstructServicesUsing(_container.Resolve);
});
before Mapper.CreateMap calls.
Created a ValueResolverInstaller like this:
public class ValueResolverInstaller : IWindsorInstaller
{
public void Install(IWindsorContainer container, IConfigurationStore store)
{
container.Register(Classes.FromThisAssembly()
.BasedOn<IValueResolver>()
.LifestyleTransient());
}
}
and the ValueResolver itself:
public class DivergencesResolver : ValueResolver<MyClass, int>
{
private AssessmentService assessmentService;
public DivergencesResolver(AssessmentService assessmentService)
{
this.assessmentService = assessmentService;
}
protected override int ResolveCore(MyClass c)
{
return assessmentService.GetAssessmentDivergences(c.AssessmentId).Count();
}
}