我的 Json 文件无法在 Visual Studio 2022 中运行

Question

在 Visual Studio 中向我的项目添加了一个 json 文件，当我在浏览器中运行它时，出现错误。

我对 Visual Studio 和 C# 还很陌生，所以我不太明白出了什么问题。

我的项目叫做恐龙 这是dinosaur.cs代码

using System.Text.Json;
using System.Text.Json.Serialization;

namespace Dinosaurs.Models
{
    public class Dinosaur
    {
        public string DinoName { get; set; }
        public string Pronounced { get; set; }
        public string BriefDesc { get; set; }
        public string NameMeans { get; set; }
        public int LengthFt { get; set; }
        public int WeightLbs { get; set; }
        public int LivedYearsAgo { get; set; }
        public string ClassID { get; set; }
        public string PeriodID { get; set; }
        public override string ToString() => JsonSerializer.Serialize<Dinosaur>(this);
    }
}

这是我的 models.cs 代码：

using System.Text.Json;
using System.Text.Json.Serialization;

namespace Dinosaurs.Models
{
    public class Dinosaur
    {
        public string DinoName { get; set; }
        public string Pronounced { get; set; }
        public string BriefDesc { get; set; }
        public string NameMeans { get; set; }
        public int LengthFt { get; set; }
        public int WeightLbs { get; set; }
        public int LivedYearsAgo { get; set; }
        public string ClassID { get; set; }
        public string PeriodID { get; set; }
        public override string ToString() => JsonSerializer.Serialize<Dinosaur>(this);
    }
}

我的 services.cs 代码

using Dinosaurs.Models;
using System.Text.Json;

namespace Dinosaurs.Services
{
    public class JsonDinosaurService
    {

        public IWebHostEnvironment WebHostEnvironment { get; }


        private string JsonFileName
        {
            get { return Path.Combine(WebHostEnvironment.WebRootPath, "data", "dinosaurs.json"); }
        }

        //Constructor
        public JsonDinosaurService(IWebHostEnvironment webHostEnvironment) 
        {
            WebHostEnvironment = webHostEnvironment;
        }

        //Get dinosaur method
        public IEnumerable<Dinosaur> GetDinosaurs()
        {
            using (var jsonFileReader = File.OpenText(JsonFileName)) 
            {
                return JsonSerializer.Deserialize<Dinosaur[]>(jsonFileReader.ReadToEnd(),
                    new JsonSerializerOptions
                    {
                        PropertyNameCaseInsensitive = true
                    });
            }
        }

    }
}

我的Startup.cs代码

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Dinosaurs.Services;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Dinosaurs
{
    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.AddRazorPages();
            services.AddTransient<JsonDinosaurService>();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Error");
                // 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.UseStaticFiles();

            app.UseRouting();

            app.UseAuthorization();

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

我尝试运行它的页面是 List.cshtml 这是List.cshtml代码

using Dinosaurs.Models;
using Dinosaurs.Services;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;

namespace Dinosaurs.Pages
{
    public class ListModel : PageModel
    {

        public JsonDinosaurService DinosaurService;

        public IEnumerable<Dinosaur> Dinosaurs { get; private set; }

        public ListModel(JsonDinosaurService dinosaurService)
        {
            DinosaurService = dinosaurService;
        }

        public void OnGet()
        {
            Dinosaurs = DinosaurService.GetDinosaurs();

        }
    }
}

是List.cshtml代码

@page
@model Dinosaurs.Pages.ListModel
@{
}




<h1>LIST OF DINOSAURS</h1>


@foreach (var dinosaur in Model.Dinosaurs)
{
    <h2>@dinosaur.DinoName</h2>
    <h2>@dinosaur.Pronounced</h2>
    <h2>@dinosaur.BriefDesc</h2>
    <h2>@dinosaur.NameMeans</h2>
    <h2>@dinosaur.LengthFt</h2>
    <h2>@dinosaur.WeightLbs</h2>
    <h2>@dinosaur.LivedYearsAgo</h2>
    <h2>@dinosaur.ClassID</h2>
    <h2>@dinosaur.PeriodID</h2>
}

Answer 1

异常说明是依赖注入失败

您没有在 Program.cs 中调用ConfigureServices，因此您的依赖项注入失败