ASP.NET中无需求的Authorization Handler如何调用context.Succeed()？

我实现了如下的Authorization Handler：

public class StationToIDMMatchHandler : IAuthorizationHandler
{
    private readonly IHttpContextAccessor _httpContextAccessor = null;
    private readonly AftermarketDbContext _db;

    public StationToIDMMatchHandler(IHttpContextAccessor httpContextAccessor, AftermarketDbContext db)
    {
        _httpContextAccessor = httpContextAccessor;
        _db = db;
    }


    public Task HandleAsync(AuthorizationHandlerContext context)
    {
        HttpContext httpContext = _httpContextAccessor.HttpContext; // Access context here

        string StationUniqueId = httpContext.Request.Headers.Where(x => x.Key == " StationUniqueId").FirstOrDefault().Value;

        var listOfRoles = context.User.Claims.Where(c => c.Type == "groups").Select(x => x.Value).ToList();

        string requiredIDMRole = _db.StationRole.Where(DbStationUniqueId => DbStationUniqueId.StationId == StationUniqueId).ToString();


        if (listOfRoles.Contains(requiredIDMRole))
        {
            context.Succeed();
            return Task.CompletedTask;
        }
        else
            return Task.CompletedTask;
    }
}

但我除了已校验的逻辑外没有其他需求，无法调用无参的context.Succeed()。请问该如何处理？是否必须创建实现IAuthorizationRequirement的空类？这似乎不是好方法。

方法一：创建空Requirement类（官方标准方案） #

这是ASP.NET Core授权系统的设计要求——context.Succeed()必须接收一个IAuthorizationRequirement实例，用来标记对应的授权要求已通过。你只需要定义一个最简单的空类即可：

public class StationToIDMMatchRequirement : IAuthorizationRequirement { }

接着修改Handler，继承泛型的AuthorizationHandler<StationToIDMMatchRequirement>而非直接实现IAuthorizationHandler，这样就能在HandleRequirementAsync方法中调用带参数的context.Succeed(requirement)：

public class StationToIDMMatchHandler : AuthorizationHandler<StationToIDMMatchRequirement>
{
    private readonly IHttpContextAccessor _httpContextAccessor;
    private readonly AftermarketDbContext _db;

    public StationToIDMMatchHandler(IHttpContextAccessor httpContextAccessor, AftermarketDbContext db)
    {
        _httpContextAccessor = httpContextAccessor;
        _db = db;
    }

    protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, StationToIDMMatchRequirement requirement)
    {
        HttpContext httpContext = _httpContextAccessor.HttpContext;
        // 修正Header键的空格问题，同时处理空值
        string stationUniqueId = httpContext.Request.Headers["StationUniqueId"].FirstOrDefault()?.Trim();

        if (string.IsNullOrEmpty(stationUniqueId))
        {
            context.Fail();
            return Task.CompletedTask;
        }

        var userRoles = context.User.Claims.Where(c => c.Type == "groups").Select(x => x.Value).ToList();
        // 修正原代码的错误：Where+ToString会输出SQL，应该用FirstOrDefault获取实体
        var stationRole = _db.StationRole.FirstOrDefault(s => s.StationId == stationUniqueId);
        
        if (stationRole != null && userRoles.Contains(stationRole.RoleName)) // 假设RoleName是存储角色的字段
        {
            context.Succeed(requirement);
        }
        else
        {
            context.Fail();
        }

        return Task.CompletedTask;
    }
}

最后在Program.cs/Startup.cs中注册授权策略和Handler：

services.AddAuthorization(options =>
{
    options.AddPolicy("StationToIDMMatch", policy =>
        policy.Requirements.Add(new StationToIDMMatchRequirement()));
});

services.AddScoped<IAuthorizationHandler, StationToIDMMatchHandler>();

方法二：遍历现有Requirements（不推荐的取巧方式） #

如果你实在不想创建空Requirement类，可以在HandleAsync中遍历context.Requirements，取任意一个实例传入context.Succeed()。但这种方式属于绕过框架设计的技巧，可读性和可维护性差，不建议在生产环境使用：

public Task HandleAsync(AuthorizationHandlerContext context)
{
    HttpContext httpContext = _httpContextAccessor.HttpContext;
    string stationUniqueId = httpContext.Request.Headers["StationUniqueId"].FirstOrDefault()?.Trim();

    if (string.IsNullOrEmpty(stationUniqueId))
        return Task.CompletedTask;

    var userRoles = context.User.Claims.Where(c => c.Type == "groups").Select(x => x.Value).ToList();
    var stationRole = _db.StationRole.FirstOrDefault(s => s.StationId == stationUniqueId);

    if (stationRole != null && userRoles.Contains(stationRole.RoleName))
    {
        var requirement = context.Requirements.FirstOrDefault();
        if (requirement != null)
        {
            context.Succeed(requirement);
        }
    }

    return Task.CompletedTask;
}

原代码的关键问题修正 #

• 读取Header时，原代码中键带有空格" StationUniqueId"，容易导致匹配失败，建议统一去掉空格或用Trim()处理
• _db.StationRole.Where(...).ToString()会返回SQL语句而非实际角色值，必须改用FirstOrDefault()获取实体后取对应字段
• 增加空值判断，避免空引用异常导致程序崩溃

内容的提问来源于stack exchange，提问作者Mr.Gomer