7

I'm using Windsor to manage IoC for my controllers in a WebAPI project. I've got a DependencyResolver working nicely to resolve controller dependencies, but now I'm looking to inject dependencies into a custom action filter I'm using to manage authentication.

I've looked into using a custom ActionInvoker but it's not clear from the interface that WebAPI is using how I would go about resolving property dependencies on the custom action filter attribute before it executes. Anyone have a good example of how to do this in the MVC 4 RC?

EDIT: I'm aware you can't do constructor injection on filters, because they're attributes and therefore instantiated by the .NET framework - but I'm hoping there's some point in the execution lifecycle that happens AFTER the filter is instantiated but BEFORE it gets executed, where I could run some custom code to enumerate across the filters' public properties and inject the necessary services.

4

2 回答 2

11

操作过滤器是属性。在 .NET 属性中，实例化过程由 .NET 运行时管理，您无法控制它。因此，一种可能性是使用Poor Man's Dependency Injection，我个人建议您不要这样做。

另一种可能性是使用标记属性：

public class MyActionFilterAttribute : Attribute 
{ 

}

然后使用构造函数注入操作过滤器：

public class MyActionFilter : ActionFilterAttribute
{
    private readonly IFoo _foo;
    public MyActionFilter(IFoo foo)
    {
        _foo = foo;
    }

    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        if (actionContext.ActionDescriptor.GetCustomAttributes<MyActionFilterAttribute>().Any())
        {
            // The action is decorated with the marker attribute => 
            // do something with _foo
        }
    }
}

然后将其注册为全局操作过滤器Application_Start：

IFoo foo = ....
GlobalConfiguration.Configuration.Filters.Add(new MyActionFilter(foo));
于 2012-06-11T11:30:19.360 回答
5

我遇到了同样的问题，但决定为此使用 ServiceLocator (DependencyResolver.GetService)，因为它在框架中似乎是一种有效的方法

public class RequiresSessionAttribute :
    ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        var sessionService =
            (ISessionService) actionContext
                    .ControllerContext.Configuration.DependencyResolver
                    .GetService(typeof (ISessionService));

        var sessionId = HttpUtility
            .ParseQueryString(actionContext.Request.RequestUri.Query)
            .Get("sessionId");

        if (sessionId == null
            || !sessionService.IsValid(sessionId))
            throw new SessionException();

        base.OnActionExecuting(actionContext);
    }
}

这是对这个属性的测试，有点痛苦但可能

public class requires_sessionId
{
    [Fact]
    void can_call_action_with_session_id()
    {
        var context = GetContext("http://example.com/?sessionId=blaa");

        var sut = new RequiresSessionAttribute();

        Assert.DoesNotThrow(
            () => sut.OnActionExecuting(context));
    }

    [Fact]
    void can_not_call_action_without_session_id()
    {
        var context = GetContext("http://example.com/");

        var sut = new RequiresSessionAttribute();

        Assert.Throws<SessionException>(
            () => sut.OnActionExecuting(context));
    }

    HttpActionContext GetContext(string url)
    {
        var sessionServiceMock = new Mock<ISessionService>();
        sessionServiceMock
            .Setup(x => x.IsValid(It.IsAny<string>()))
            .Returns(true);

        var dependancyResolverMock = new Mock<IDependencyResolver>();
        dependancyResolverMock
            .Setup(x => x.GetService(It.IsAny<Type>()))
            .Returns(sessionServiceMock.Object);

        var config = new HttpConfiguration
               {
                   DependencyResolver = dependancyResolverMock.Object
               };
        var controllerContext = new HttpControllerContext
               {
                    Configuration = config,
                    Request = new HttpRequestMessage(
                               HttpMethod.Get,
                               url)
                };

        return
            new HttpActionContext
                {
                    ControllerContext = controllerContext,
                };
    }
}
于 2012-08-16T13:09:26.510 回答