如何在 .Net Core ActionFilterAttribute 中使用依赖注入? [英] How can I use Dependency Injection in a .Net Core ActionFilterAttribute?

问题描述

AuthenticationRequiredAttribute 类

public class AuthenticationRequiredAttribute : ActionFilterAttribute
{
    ILoginTokenKeyApi _loginTokenKeyApi;
    IMemoryCache _memoryCache;

    public AuthenticationRequiredAttribute(IMemoryCache memoryCache)
    {
        _memoryCache = memoryCache;

        _loginTokenKeyApi = new LoginTokenKeyController(new UnitOfWork());
    }

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        var memory = _memoryCache.Get(Constants.KEYNAME_FOR_AUTHENTICATED_PAGES);

        string requestedPath = filterContext.HttpContext.Request.Path;

        string tokenKey = filterContext.HttpContext.Session.GetString("TokenKey")?.ToString();

        bool? isLoggedIn = _loginTokenKeyApi.IsLoggedInByTokenKey(tokenKey).Data;

        if (isLoggedIn == null ||
            !((bool)isLoggedIn) ||
            !Constants.AUTHENTICATED_PAGES_FOR_NORMAL_USERS.Contains(requestedPath))
        {
            filterContext.Result = new JsonResult(new { HttpStatusCode.Unauthorized });
        }
    }
    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
    }
}

HomeController

public class HomeController : Controller
{
    IUserApi _userApi;
    ILoginTokenKeyApi _loginTokenKey;
    IMemoryCache _memoryCache;

    public HomeController(IUserApi userApi, ILoginTokenKeyApi loginTokenKey, IMemoryCache memoryCache)
    {
        _loginTokenKey = loginTokenKey;
        _userApi = userApi;

        _memoryCache = memoryCache;
    }

    [AuthenticationRequired] // There is AN ERROR !!
    public IActionResult Example()
    {
        return View();
    }
}

错误:

错误 CS7036 没有给出对应于所需的形式参数 'memoryCache''AuthenticationRequiredAttribute.AuthenticationRequiredAttribute(IMemoryCache)' Project.Ground.WebUI

Error CS7036 There is no argument given that corresponds to the required formal parameter 'memoryCache' of 'AuthenticationRequiredAttribute.AuthenticationRequiredAttribute(IMemoryCache)' Project.Ground.WebUI

我的问题实际上是:我不能在属性类中使用依赖注入.

我想在没有任何参数的情况下使用该属性.有没有办法解决它?我使用依赖注入，但它不能用于属性.我如何使用它?

I want to use that attribute without any parameter. Is there any solution to solve it? I use dependency injection but it cant be used for attributes. How I can use it?

推荐答案

ActionExecutingContext.HttpContext.RequestServices 应该在构造时给您一个对请求的服务容器的引用，而不是在构造时解析请求.

Instead of resolving at construction, ActionExecutingContext.HttpContext.RequestServices should give you a reference to the request's service container at the time of the request.

所以:

public override void OnActionExecuting(ActionExecutingContext filterContext)
{
    var svc = filterContext.HttpContext.RequestServices;
    var memCache = svc.GetService<IMemoryCache>();
    //..etc

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