ASP.NET Core 2.1 如何调用引用类的过滤器

Question

我有一个要从函数调用的操作过滤器。但是，在此过滤器中，我指的是另一个名为 ValidateRoleClient 的类。如何进行服务注入？或者在我的函数中正确调用这个类？

public class RolesFilterAttribute : ActionFilterAttribute
{
    public ValidateRoleClient validateRoleClient;
    public string Role { get; set; }

    public RolesFilterAttribute(ValidateRoleClient validateRoleClient)
    {
        this.validateRoleClient = validateRoleClient;
    }

    public override void OnActionExecuting(ActionExecutingContext context)
    {
        if (context.HttpContext.Request.Cookies["Token"] != null || context.HttpContext.Request.Cookies["RefreshToken"] != null)
        {
            TokenViewModel tvm = new TokenViewModel
            {
                Token = context.HttpContext.Request.Cookies["Token"],
                RefreshToken = context.HttpContext.Request.Cookies["RefreshToken"]
            };
            ValidateRoleViewModel vrvm = new ValidateRoleViewModel
            {
                Role = Role,
                Token = tvm
            };
            validateRoleClient.ValidateRole(vrvm);
        }
    }
}

这就是我在函数中引用过滤器的方式

[RolesFilter]
public IActionResult About()
{
    return View();
}

我从中得到的当前错误是

严重性代码描述项目文件行抑制 状态错误 CS7036 没有给出对应于的参数 所需的形式参数“validateRoleClient” 'RolesFilterAttribute.RolesFilterAttribute(ValidateRoleClient)'

Answer 1

您可以像这样将属性包装在 FilterFactory 中：

public class RolesFilterAttribute : Attribute, IFilterFactory
{
    public string Role { get; set; }       

    public IFilterMetadata CreateInstance(IServiceProvider serviceProvider)
    {
        return new RolesFilterAttributeImplementation(
            serviceProvider.GetRequiredService<ValidateRoleClient>(),
            Role
        );
    }

    private class RolesFilterAttributeImplementation : ActionFilterAttribute
    {
        private readonly ValidateRoleClient validateRoleClient;
        private readonly string role;

        public RolesFilterAttributeImplementation(ValidateRoleClient validateRoleClient, string role)
        {
            this.validateRoleClient = validateRoleClient;
            this.role = role;
        }

        public override void OnActionExecuting(ActionExecutingContext context)
        {
            if (context.HttpContext.Request.Cookies["Token"] != null || context.HttpContext.Request.Cookies["RefreshToken"] != null)
            {
                TokenViewModel tvm = new TokenViewModel
                {
                    Token = context.HttpContext.Request.Cookies["Token"],
                    RefreshToken = context.HttpContext.Request.Cookies["RefreshToken"]
                };
                ValidateRoleViewModel vrvm = new ValidateRoleViewModel
                {
                    Role = role,
                    Token = tvm
                };
                validateRoleClient.ValidateRole(vrvm);
            }
        }
    }

    public bool IsReusable => false;
}

当然ValidateRoleClient服务必须先配置为注入。

然后您可以像往常一样使用RolesFilterAttribute 属性。

您可以在此处阅读有关IFilterFactory 的更多信息：https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/filters?view=aspnetcore-2.1#ifilterfactory