C# Asp.net核心中间件中的访问模型状态_C#_Asp.net Core_Asp.net Core Middleware_.net Core 2.1

C# Asp.net核心中间件中的访问模型状态

c# asp.net-core

C# Asp.net核心中间件中的访问模型状态,c#,asp.net-core,asp.net-core-middleware,.net-core-2.1,C#,Asp.net Core,Asp.net Core Middleware,.net Core 2.1,我需要访问Asp.net Core 2.1中间件中的ModelState，但这只能从Controller访问例如，我有responseFormatMiddleware，在这个中间件中，我需要忽略ModelState错误，并在“响应消息”中显示它的错误： public class ResponseFormatterMiddleware { private readonly RequestDelegate _next; private readonly ILogger<Res

我需要访问Asp.net Core 2.1中间件中的

ModelState

，但这只能从

Controller

访问

例如，我有

responseFormatMiddleware

，在这个中间件中，我需要忽略

ModelState

错误，并在“响应消息”中显示它的错误：

public class ResponseFormatterMiddleware
{
    private readonly RequestDelegate _next;
    private readonly ILogger<ResponseFormatterMiddleware> _logger;
    public ResponseFormatterMiddleware(RequestDelegate next, ILoggerFactory loggerFactory)
    {
        _next = next ?? throw new ArgumentNullException(nameof(next));
        _logger = loggerFactory?.CreateLogger<ResponseFormatterMiddleware>() ?? throw new ArgumentNullException(nameof(loggerFactory));
    }

    public async Task Invoke(HttpContext context)
    {
        var originBody = context.Response.Body;

        using (var responseBody = new MemoryStream())
        {
            context.Response.Body = responseBody;
            // Process inner middlewares and return result.
            await _next(context);

            responseBody.Seek(0, SeekOrigin.Begin);
            using (var streamReader = new StreamReader(responseBody))
            {
                // Get action result come from mvc pipeline
                var strActionResult = streamReader.ReadToEnd();
                var objActionResult = JsonConvert.DeserializeObject(strActionResult);
                context.Response.Body = originBody;

                // if (!ModelState.IsValid) => Get error message

                // Create uniuqe shape for all responses.
                var responseModel = new GenericResponseModel(objActionResult, (HttpStatusCode)context.Response.StatusCode, context.Items?["Message"]?.ToString());

                // Set all response code to 200 and keep actual status code inside wrapped object.
                context.Response.StatusCode = (int)HttpStatusCode.OK;
                context.Response.ContentType = "application/json";
                await context.Response.WriteAsync(JsonConvert.SerializeObject(responseModel));
            }
        }
    }
}

// Extension method used to add the middleware to the HTTP request pipeline.
public static class ResponseFormatterMiddlewareExtensions
{
    public static IApplicationBuilder UseResponseFormatter(this IApplicationBuilder builder)
    {
        return builder.UseMiddleware<ResponseFormatterMiddleware>();
    }
}

[Serializable]
[DataContract]
public class GenericResponseModel
{
    public GenericResponseModel(object result, HttpStatusCode statusCode, string message)
    {
        StatusCode = (int)statusCode;
        Result = result;
        Message = message;
    }
    [DataMember(Name = "result")]
    public object Result { get; set; }

    [DataMember(Name = "statusCode")]
    public int StatusCode { get; set; }

    [DataMember(Name = "message")]
    public string Message { get; set; }

    [DataMember(Name = "version")]
    public string Version { get; set; } = "V1.0"
}

但现在观察到的结果是：

{
    "result": {
        "Name": [
            "Name is required"
        ]
    },
    "statusCode": 400,
    "message": null,
    "version": "V1"
}

如果您正在实现类似的内容，则可以通过“ActionFilterAttribute”基类的重写方法的参数来访问它

public class ModelStateValidationFilter : ActionFilterAttribute
{
     public override void OnActionExecuting(ActionExecutingContext context)
     {
         // You can access it via context.ModelState
         ModelState.AddModelError("YourFieldName", "Error details...");
         base.OnActionExecuting(context);
     }
}

ModelState

仅在模型绑定后可用。只需使用操作过滤器自动存储

ModelState

，就可以在中间件中使用它

首先，添加一个操作过滤器，将ModelState设置为功能：

public class ModelStateFeatureFilter : IAsyncActionFilter
{

    public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
    {
        var state = context.ModelState;
        context.HttpContext.Features.Set<ModelStateFeature>(new ModelStateFeature(state));
        await next();
    }
}

要使动作过滤器自动进行，我们需要配置MVC

services.AddMvc(opts=> {
    opts.Filters.Add(typeof(ModelStateFeatureFilter));
})

现在我们可以在中间件中使用

ModelState

，如下所示：

public class ResponseFormatterMiddleware
{
    // ...

    public async Task Invoke(HttpContext context)
    {
        var originBody = context.Response.Body;

        using (var responseBody = new MemoryStream())
        {
            context.Response.Body = responseBody;
            // Process inner middlewares and return result.
            await _next(context);

            var ModelState = context.Features.Get<ModelStateFeature>()?.ModelState;
            if (ModelState==null) {
                return ;      //  if you need pass by , just set another flag in feature .
            }

            responseBody.Seek(0, SeekOrigin.Begin);
            using (var streamReader = new StreamReader(responseBody))
            {
                // Get action result come from mvc pipeline
                var strActionResult = streamReader.ReadToEnd();
                var objActionResult = JsonConvert.DeserializeObject(strActionResult);
                context.Response.Body = originBody;

               // Create uniuqe shape for all responses.
                var responseModel = new GenericResponseModel(objActionResult, (HttpStatusCode)context.Response.StatusCode, context.Items?["Message"]?.ToString());

                // => Get error message
                if (!ModelState.IsValid)
                {
                    var errors= ModelState.Values.Where(v => v.Errors.Count > 0)
                        .SelectMany(v=>v.Errors)
                        .Select(v=>v.ErrorMessage)
                        .ToList();
                    responseModel.Result = null;
                    responseModel.Message = String.Join(" ; ",errors) ;
                } 

                // Set all response code to 200 and keep actual status code inside wrapped object.
                context.Response.StatusCode = (int)HttpStatusCode.OK;
                context.Response.ContentType = "application/json";
                await context.Response.WriteAsync(JsonConvert.SerializeObject(responseModel));
            }
        }
    }
}

和一个简单的控制器：

public class HomeController : Controller
{

    public IActionResult Index(string name)
    {
        return new JsonResult(new {
            Name=name
        });
    }

    [HttpPost]
    public IActionResult Person([Bind("Age,Name")]MyModel model)
    {
        return new JsonResult(model);
    }
}

如果我们发送带有有效负载的请求：

POST https://localhost:44386/Home/Person HTTP/1.1
content-type: application/x-www-form-urlencoded

name=helloo&age=20

答复将是：

HTTP/1.1 200 OK
Transfer-Encoding: chunked
Content-Type: application/json
Server: Kestrel
X-SourceFiles: =?UTF-8?B?RDpccmVwb3J0XDIwMThcOVw5LTE4XEFwcFxBcHBcQXBwXEhvbWVcUGVyc29u?=
X-Powered-By: ASP.NET

{
  "result": {
    "name": "helloo",
    "age": 20
  },
  "statusCode": 200,
  "message": null,
  "version": "V1.0"
}

如果我们发送的请求模型无效：

POST https://localhost:44386/Home/Person HTTP/1.1
content-type: application/x-www-form-urlencoded

name=hello&age=i20

答复将是：

HTTP/1.1 200 OK
Transfer-Encoding: chunked
Content-Type: application/json
Server: Kestrel
X-SourceFiles: =?UTF-8?B?RDpccmVwb3J0XDIwMThcOVw5LTE4XEFwcFxBcHBcQXBwXEhvbWVcUGVyc29u?=
X-Powered-By: ASP.NET

{
  "result": null,
  "statusCode": 200,
  "message": "The value 'i20' is not valid for Age. ; The field Name must be a string or array type with a minimum length of '6'.",
  "version": "V1.0"
}

我在.net core 2.2中也遇到了一些问题，似乎

IAsyncationFilter

在我的案例中不起作用，但使用了

IActionResult

。下面是我修改过的代码，但不确定这是否是我想要的

public class ModelStateFeatureFilter : IActionResult
{
    public Task ExecuteResultAsync(ActionContext context)
    {
        var state = context.ModelState;
        context.HttpContext.Features.Set(new ModelStateFeature(state));
        return Task.CompletedTask;
    }
}

和下面的启动类

services.Configure<ApiBehaviorOptions>(options =>
{
    options.InvalidModelStateResponseFactory = ctx => new ModelStateFeatureFilter();
});

services.Configure（选项=>
{
options.InvalidModelStateResponseFactory=ctx=>new-ModelStateFeatureFilter（）；
});

是的，我知道，但我需要它在Middleware什么样的

中间件？您能描述一下访问ModelState
的目的吗？确切地说，我需要一些模型绑定信号我没有得到它。为什么？你想忽略什么？在什么情况下使用？假设一个属性可以是单属性，也可以是多属性，这取决于AllowMultiple属性，在这种情况下，可能可以使用ModelState
在一般中间件中根本不存在。这是一个MVC概念。使用这种方法，当ModelState.IsValid==false时，我很难启动OnActionExecutionAsync。很明显，当你回答这个问题时，它起了作用，所以我想知道asp.net core 2.2中是否有什么变化？@raterus我只是在asp.net core 2.2中尝试上面的代码，它对我来说很好。您是否在UseMvc（）
之后注册了中间件。如果是这样，它就不会生效。并确保已将modelstateffeaturefilter添加到MVC服务中。
HTTP/1.1 200 OK
Transfer-Encoding: chunked
Content-Type: application/json
Server: Kestrel
X-SourceFiles: =?UTF-8?B?RDpccmVwb3J0XDIwMThcOVw5LTE4XEFwcFxBcHBcQXBwXEhvbWVcUGVyc29u?=
X-Powered-By: ASP.NET

{
  "result": null,
  "statusCode": 200,
  "message": "The value 'i20' is not valid for Age. ; The field Name must be a string or array type with a minimum length of '6'.",
  "version": "V1.0"
}

public class ModelStateFeatureFilter : IActionResult
{
    public Task ExecuteResultAsync(ActionContext context)
    {
        var state = context.ModelState;
        context.HttpContext.Features.Set(new ModelStateFeature(state));
        return Task.CompletedTask;
    }
} 

services.Configure<ApiBehaviorOptions>(options =>
{
    options.InvalidModelStateResponseFactory = ctx => new ModelStateFeatureFilter();
});