Второй параметр AsWebApiAuthorizationFilterFor - это селектор действий, используемый для выбора одного метода, для которого создается фильтр.
Чтобы применить условную регистрацию, вы можете использовать OnlyIf:
// Conditionally register filter for all controller actions
services.GetContainerBuilder()
.RegisterType<Filter>()
.AsWebApiAuthorizationFilterFor<DummyController>()
.OnlyIf(_ => typeof(DummyController).GetCustomAttributes<SomeAttribute>().Any());
// Conditionally register filter for selected controller action
services.GetContainerBuilder()
.RegisterType<Filter>()
// x => x.Get selects Get method defined by DummyController
.AsWebApiAuthorizationFilterFor<DummyController>(x => x.Get())
.OnlyIf(_ =>
typeof(DummyController).GetMethod("Get").GetCustomAttributes<SomeAttribute>().Any());
Вы также можете создать собственное расширение AsWebApiAuthorizationFilterForOnlyIf и сделать:
if (typeof(DummyController).GetCustomAttributes<SomeAttribute>().Any())
{
services.GetContainerBuilder()
.RegisterType<Filter>()
.AsWebApiAuthorizationFilterFor<DummyController>();
}
ОБНОВЛЕНИЕ
Если вам нравится scan-and-add-automatically метод, вы можете использовать дерево выражений для динамического вызова AsWebApiAuthorizationFilterFor для каждого найденного контроллера и метода. Там будет довольно много кода, как вы могли видеть ниже:
ContainerBuilder containerBuilder = ...
Type[] controllerTypes = ...
// Keep the type registration builder here, and use it for all As actions
var typeRegistrationBuilder = containerBuilder
.RegisterType<Filter>()
.InstancePerRequest();
// Scan controllers and methods and build registrations
foreach (Type controllerType in controllerTypes)
{
// Which means ALL actions in the controller should have the filter registered
if (controllerType.GetCustomAttributes<SomeAttribute>().Any())
{
// Because AsWebApiAuthorizationFilterFor doesn't take non-generic type parameter,
// so we need to build delegate to invoke AsWebApiAuthorizationFilterFor<controllerType>.
// Use expression tree.
// This will build:
// () => typeRegistrationBuilder.AsWebApiAuthorizationFilterFor<controllerType>()
Expression.Lambda<Action>(
Expression.Call(
typeof(Autofac.Integration.WebApi.RegistrationExtensions),
"AsWebApiAuthorizationFilterFor",
new[] { controllerType },
Expression.Constant(typeRegistrationBuilder))
).Compile()(); // Just compile and run this Action
continue;
}
// Controller doesn't have the attribute
// Scan action methods
var methods = controllerType.GetMethods()
.Where(mi => mi.GetCustomAttributes<SomeAttribute>().Any());
foreach (MethodInfo method in methods)
{
// Now the method has the attribute
// Again, use expression tree to build method call, but this time, with a selector
// First, build method call expression parameters for each parameter on the method
// Just need to pass default(T) in, because Autofac literally just need the method
IEnumerable<Expression> parameters = method.GetParameters()
.Select(p => p.ParameterType)
.Select(Expression.Default);
// Build method selector
// This will build:
// _ => _.SomeMethod(parameters)
ParameterExpression controller = Expression.Parameter(controllerType, "_");
LambdaExpression methodSelector = Expression.Lambda(
typeof(Action<>).MakeGenericType(controllerType),
Expression.Call(controller, method, parameters),
controller);
// This will build:
// () => typeRegistrationBuilder.AsWebApiAuthorizationFilterFor<controllerType>(
// _ => _.SomeMethod(parameters));
Expression.Lambda<Action>(
Expression.Call(
typeof(Autofac.Integration.WebApi.RegistrationExtensions),
"AsWebApiAuthorizationFilterFor",
new[] { controllerType },
Expression.Constant(typeRegistrationBuilder),
methodSelector)
).Compile()(); // Just compile and run this Action
}
}