c# - 我的 NET Core Web API Controller 出现“找不到页面”错误

Question

我在 Visual Studio 2019 上使用 C# 进行编码，我正在使用 2019 款 MacBook。我的应用程序是 NET Core Web API 2.2。我的 Controller 是一个 API Controller ，带有使用 Entity Framework 的操作。

我在开始项目之前运行了我的应用程序，它运行良好，我已经连接到我的 sql server，进行了迁移并更新了我的数据库。当我在没有调试的情况下运行应用程序时，它对值 Controller (https://localhost:5001/api/values)工作正常，但是当我输入我的“贷款 Controller ”(https://localhost:5001/api/loan)的名称时，它会收到 HTTP 错误“This localhost page can't找不到网页地址:https://localhost:5001/api/loan '

这是 LoanController.cs 文件的代码

using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.EntityFrameworkCore;
using WebAPI.Models;

namespace WebAPI.Controllers
{
    public class LoanController : Controller
    {
        private readonly LoanContext _context;

        public LoanController(LoanContext context)
        {
            _context = context;
        }

        // GET: Loan
        public async Task<IActionResult> Index()
        {
            return View(await _context.Loans.ToListAsync());
        }

        // GET: Loan/Details/5
        public async Task<IActionResult> Details(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var loan = await _context.Loans
                .FirstOrDefaultAsync(m => m.LoanCode == id);
            if (loan == null)
            {
                return NotFound();
            }

            return View(loan);
        }

        // GET: Loan/Create
        public IActionResult Create()
        {
            return View();
        }

        // POST: Loan/Create
        // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
        // more details see http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create([Bind("LoanCode,LoanID,BorrowerName,FundingAmount,RepaymentAmount")] Loan loan)
        {
            if (ModelState.IsValid)
            {
                _context.Add(loan);
                await _context.SaveChangesAsync();
                return RedirectToAction(nameof(Index));
            }
            return View(loan);
        }

        // GET: Loan/Edit/5
        public async Task<IActionResult> Edit(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var loan = await _context.Loans.FindAsync(id);
            if (loan == null)
            {
                return NotFound();
            }
            return View(loan);
        }

        // POST: Loan/Edit/5
        // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
        // more details see http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Edit(int id, [Bind("LoanCode,LoanID,BorrowerName,FundingAmount,RepaymentAmount")] Loan loan)
        {
            if (id != loan.LoanCode)
            {
                return NotFound();
            }

            if (ModelState.IsValid)
            {
                try
                {
                    _context.Update(loan);
                    await _context.SaveChangesAsync();
                }
                catch (DbUpdateConcurrencyException)
                {
                    if (!LoanExists(loan.LoanCode))
                    {
                        return NotFound();
                    }
                    else
                    {
                        throw;
                    }
                }
                return RedirectToAction(nameof(Index));
            }
            return View(loan);
        }

        // GET: Loan/Delete/5
        public async Task<IActionResult> Delete(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var loan = await _context.Loans
                .FirstOrDefaultAsync(m => m.LoanCode == id);
            if (loan == null)
            {
                return NotFound();
            }

            return View(loan);
        }

        // POST: Loan/Delete/5
        [HttpPost, ActionName("Delete")]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> DeleteConfirmed(int id)
        {
            var loan = await _context.Loans.FindAsync(id);
            _context.Loans.Remove(loan);
            await _context.SaveChangesAsync();
            return RedirectToAction(nameof(Index));
        }

        private bool LoanExists(int id)
        {
            return _context.Loans.Any(e => e.LoanCode == id);
        }
    }
}

这是 ValuesController.cs 文件

using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;

namespace WebAPI.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        // GET api/values
        [HttpGet]
        public ActionResult<IEnumerable<string>> Get()
        {
            return new string[] { "value1", "value2" };
        }

        // GET api/values/5
        [HttpGet("{id}")]
        public ActionResult<string> Get(int id)
        {
            return "value";
        }

        // POST api/values
        [HttpPost]
        public void Post([FromBody] string value)
        {
        }

        // PUT api/values/5
        [HttpPut("{id}")]
        public void Put(int id, [FromBody] string value)
        {
        }

        // DELETE api/values/5
        [HttpDelete("{id}")]
        public void Delete(int id)
        {
        }
    }
}

Startup.cs文件

using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Google.Protobuf.WellKnownTypes;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Routing;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using WebAPI.Models;

namespace WebAPI
{
    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.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

            services.AddDbContext<LoanContext>(options =>
            options.UseSqlServer(Configuration.GetConnectionString("DevConnection")));
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseMvc();
        }
    }
}

Launchsetting.JSON 文件

  "$schema": "http://json.schemastore.org/launchsettings.json",
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:41196",
      "sslPort": 44395
    }
  },
  "profiles": {
    "IIS Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "launchUrl": "api/values",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "WebAPI": {
      "commandName": "Project",
      "launchBrowser": true,
      "launchUrl": "api/values",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      },
      "applicationUrl": "https://localhost:5001;http://localhost:5000"
    }
  }
}

Answer 1

你需要添加

[Route("api/[controller]")]

以上

public class LoanController : Controller

这样它就可以定位到 Loan 路由。这已经适用于您的 ValuesController。

参见 Microsoft docs - Token replacement in route templates

[controller] 在设置路由时被你的 Controller 名称('Loan')替换，因此它匹配路由 'api/loan'。