约束引用 'string' 无法解析为类型

Question

大家早上好。我正在 .net 5 上创建一个应用程序，直到昨晚它都运行良好，现在我正在测试并且我收到一条错误消息，即使没有对代码进行任何更改，所以我真的不知道为什么。

那是错误：

    System.InvalidOperationException: The constraint reference 'string' could not be resolved to a type. Register the constraint type with 'Microsoft.AspNetCore.Routing.RouteOptions.ConstraintMap'.
   at Microsoft.AspNetCore.Routing.DefaultParameterPolicyFactory.Create(RoutePatternParameterPart parameter, String inlineText)
   at Microsoft.AspNetCore.Routing.ParameterPolicyFactory.Create(RoutePatternParameterPart parameter, RoutePatternParameterPolicyReference reference)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.CreateCandidate(Endpoint endpoint, Int32 score)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.CreateCandidates(IReadOnlyList`1 endpoints)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.AddNode(DfaNode node, DfaState[] states, Int32 exitDestination)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.AddNode(DfaNode node, DfaState[] states, Int32 exitDestination)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.<AddNode>g__Transition|26_0(DfaNode next, <>c__DisplayClass26_0& )
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.AddNode(DfaNode node, DfaState[] states, Int32 exitDestination)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.AddNode(DfaNode node, DfaState[] states, Int32 exitDestination)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.AddNode(DfaNode node, DfaState[] states, Int32 exitDestination)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.AddNode(DfaNode node, DfaState[] states, Int32 exitDestination)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherBuilder.Build()
   at Microsoft.AspNetCore.Routing.Matching.DataSourceDependentMatcher.CreateMatcher(IReadOnlyList`1 endpoints)
   at Microsoft.AspNetCore.Routing.DataSourceDependentCache`1.Initialize()
   at System.Threading.LazyInitializer.EnsureInitializedCore[T](T& target, Boolean& initialized, Object& syncLock, Func`1 valueFactory)
   at System.Threading.LazyInitializer.EnsureInitialized[T](T& target, Boolean& initialized, Object& syncLock, Func`1 valueFactory)
   at Microsoft.AspNetCore.Routing.Matching.DataSourceDependentMatcher..ctor(EndpointDataSource dataSource, Lifetime lifetime, Func`1 matcherBuilderFactory)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcherFactory.CreateMatcher(EndpointDataSource dataSource)
   at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.InitializeCoreAsync()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.<Invoke>g__AwaitMatcher|8_0(EndpointRoutingMiddleware middleware, HttpContext httpContext, Task`1 matcherTask)
   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

HEADERS
=======
Accept: text/plain
Accept-Encoding: gzip, deflate, br
Accept-Language: pt-PT,pt;q=0.9,en-US;q=0.8,en;q=0.7
Connection: close
Host: localhost:44335
Referer: https://localhost:44335/swagger/index.html
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.131 Safari/537.36
sec-ch-ua: "Chromium";v="92", " Not A;Brand";v="99", "Google Chrome";v="92"
sec-ch-ua-mobile: ?0
sec-fetch-site: same-origin
sec-fetch-mode: cors
sec-fetch-dest: empty
dnt: 1

这是我的初创公司：

    using System.Reflection;
using AutoMapper;
using AviationSystem.Api.Configurations;
using FluentValidation.AspNetCore;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.OpenApi.Models;
using Newtonsoft.Json;

namespace AviationSystem.Api
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDependencyInjection(Configuration);

            services
                .AddControllers()
                .AddNewtonsoftJson(
                      options => { options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore; }
                )
                .AddFluentValidation(opt =>
                {
                    opt.RegisterValidatorsFromAssembly(Assembly.GetExecutingAssembly(), lifetime: ServiceLifetime.Singleton);
                });

            services.AddAutoMapper();

            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "AviationSystem.Api", Version = "v1" });
            });

            services.AddCors(options => options.AddPolicy("Development", x => x
                .AllowAnyMethod()
                .AllowAnyHeader()
                .WithOrigins("http://localhost:4200")
                .AllowCredentials()));

            services.AddCors(options => options.AddPolicy("Production", x => x
                .AllowAnyMethod()
                .AllowAnyHeader()
                .WithOrigins("http://localhost:4200")
                .AllowCredentials()));
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IMapper mapper)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "AviationSystem.Api v1"));
            }

            mapper.ConfigurationProvider.AssertConfigurationIsValid();

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseCors(env.EnvironmentName);

            app.UseAuthentication();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

我不明白为什么会发生这种情况，因为它在昨天之前运行良好，但现在却不行了。

我也遇到了 CORS 错误，即使在我的启动时配置了这个，正如你在上面看到的那样。

Answer 1

如果您正在使用类似于 [HttpGet("example/{param1:string}/{param2:Guid}")] 的控制器，则只需删除 :string。将其更改为 [HttpGet("example/{param1}/{param2:Guid}")].

对于你的 cors 问题：-

使用下面的代码：-

app.UseCors(x => x.AllowAnyHeader().AllowAnyMethod().WithOrigins("https://localhost:4200"));

显然，你必须安装Microsoft.AspNetCore.Cors

希望它能解决您的问题。

更新

实际上并不清楚主要问题出在哪里。

如果您想确保只允许使用字母字符，则必须在收到数据后在控制器内部执行该检查。

 public async Task<IActionResult> GetUserByNameIdentifier([FromRoute] string nameIdentifier)

Answer 2

尝试：

[HttpGet("{nombre:string}",Name = "GetListaCursoporNombre")]

约束引用 'string' 无法解析为类型

The constraint reference 'string' could not be resolved to a type

c#

asp.net-core

.net-5