将 ApplicationModel 的一个实例注入到 MVC 服务中，该服务本身就是一个单例

Question

我希望仅当主体有权访问这些组件时才显示导航树的组件（无论是基于角色还是基于策略）。

我对 MVC 核心不是特别熟悉，但迄今为止的阅读表明我可以构建一个列表，列出哪些授权过滤器将应用于某个操作，例如：

    public NavigationNodePermissionResolver(ApplicationModel appModel)
    {
        foreach (var controllerModel in appModel.Controllers)
        {
            var contextFilters = controllerModel.Filters.OfType<IAsyncAuthorizationFilter>().ToList();
            foreach (ActionModel action in controllerModel.Actions)//todo restrain to HttpGet
            {
                var actionFilters = action.Filters.OfType<IAsyncAuthorizationFilter>().ToList();
            }
        }

如何将应用程序模型的实例注入 NavigationNodePermissionResolver 的实例化器中？

NavigationNodePermissionResolver 本身可以注入为：

services.TryAddSingleton<INavigationNodePermissionResolver, NavigationNodePermissionResolver>();

编辑

这个问题的后续 - 当我有一个 IAsyncAuthorizationFilters 列表时该怎么办是in this so question。

作为后续信息，ApplicationModel 是我在this SO answer 中发现的 ApplicationModelProviderContext 的一个属性 - 它似乎大致是我所追求的，但它可能是我用来获取然后执行的方法授权过滤器完全错误

Answer 1

我发现我可以实例化和注入实现 2 个接口的同一个实例。我最终进入了 Startup.ConfigureServices：

var customAppModelProvider = new CustomApplicationModelProvider();
services.AddSingleton<IApplicationModelProvider>(customAppModelProvider);
services.AddSingleton<IActionFilterMap>(customAppModelProvider);

以及实现：

public interface IActionFilterMap
{
    IEnumerable<IAsyncAuthorizationFilter> GetFilters(string area, string controller, string action);
}
public class CustomApplicationModelProvider : IApplicationModelProvider, IActionFilterMap
{
    //It will be executed after AuthorizationApplicationModelProvider, which has order -990
    public int Order => 0;

    private ReadOnlyDictionary<ActionKey, IEnumerable<IAsyncAuthorizationFilter>> _authDictionary;

    public IEnumerable<IAsyncAuthorizationFilter> GetFilters(string area, string controller, string action)
    {
        var key = new ActionKey(area, controller, action);
        if (_authDictionary.TryGetValue(key, out IEnumerable<IAsyncAuthorizationFilter> returnVar))
        {
            return returnVar;
        }
        return null;//returning null rather than Enumerable.Empty so consuming method can detect if action found and has no Authorization, or action not found

    }

    public void OnProvidersExecuted(ApplicationModelProviderContext context)
    {
        var returnVar = new Dictionary<ActionKey, IEnumerable<IAsyncAuthorizationFilter>>();
        foreach (var controllerModel in context.Result.Controllers)
        {
            var controllerFilters = controllerModel.Filters.OfType<IAsyncAuthorizationFilter>().ToList();
            string area = controllerModel.Attributes.OfType<AreaAttribute>().FirstOrDefault()?.RouteValue;
            foreach (ActionModel action in controllerModel.Actions)//todo restrain to get
            {
                var method = action.Attributes.OfType<HttpMethodAttribute>().FirstOrDefault();
                if (method == null || method.HttpMethods.Contains("GET"))
                {
                    var key = new ActionKey(area, controllerModel.ControllerName, action.ActionName);
                    if (action.Filters.OfType<AllowAnonymousFilter>().Any())
                    {
                        returnVar.Add(key, Enumerable.Empty<IAsyncAuthorizationFilter>());
                    }
                    else
                    {
                        var filters = controllerFilters.Concat(action.Filters.OfType<IAsyncAuthorizationFilter>()).ToArray();
                        returnVar.Add(key, filters);
                    }
                }
            }
            _authDictionary = new ReadOnlyDictionary<ActionKey, IEnumerable<IAsyncAuthorizationFilter>>(returnVar);
        }
    }

    public void OnProvidersExecuting(ApplicationModelProviderContext context)
    {
        //empty
    }

    private class ActionKey : Tuple<string, string, string>
    {
        public ActionKey(string area, string controller, string action) : base(area ?? string.Empty, controller, action)
        {
            _hashCode = base.GetHashCode();
        }

        int _hashCode;
        public override int GetHashCode()
        {
            return _hashCode;
        }
    }
}