错误：当 dotnet ef 迁移添加 InitialMigration 时构建失败

Question

我正在尝试创建一个 Web API。每次运行 dotnet ef migrations add InitialMigration 时，都会出现构建失败错误。我正在按照 youtube 教程使用 ASP.NET 和 Angular 以及 Postgresql 作为数据库构建仪表板。我尝试查找文档，浏览了过去的 StackOverflow 查询，但我能做的一切仍然无法解决这个问题。仅仅因为这个问题，我在我的项目中被困了 5 天。

.NET SDK 5.0

Advantage.API.csproj

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
    <UserSecretsId>User-Secret-Id</UserSecretsId>
  </PropertyGroup>

  <ItemGroup>
  <Folder Include="wwwroot\" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="5.0.7">
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
      <PrivateAssets>all</PrivateAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="5.0.7">
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
      <PrivateAssets>all</PrivateAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools.DotNet" Version="2.0.3" />
    <PackageReference Include="Microsoft.Extensions.SecretManager.Tools" Version="2.0.2" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.4" />
    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="5.0.6" />
    <PackageReference Include="Swashbuckle.AspNetCore" Version="5.6.3" />
  </ItemGroup>

</Project>

ApiContext.cs

using Microsoft.EntityFrameworkCore;

namespace Advantage.API.Demo.Models
{
    public class ApiContext : DbContext
    {
        public ApiContext(DbContextOptions<ApiContext> options) : base(options) { }

        public DbSet<Customer> Customers { get; set; }
        public DbSet<Order> Orders { get; set; }
        public DbSet<Server> Servers { get; set; }
    }
}

程序.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace Advantage.API
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}

Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.EntityFrameworkCore;
using Advantage.API.Models;


namespace Advantage.API
{
    public class Startup
    {
        private string _connectionString = null;
        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)
        {

            _connectionString = Configuration["secretConnectionString"];
            services.AddControllers();
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "Advantage.API", Version = "v1" });
            });
            services.AddEntityFrameworkNpgsql().AddDbContext<ApiContext>(opt=>opt.UseNpgsql(_connectionString));
        }

        // 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();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "Advantage.API v1"));
            }

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthorization();

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

Answer 1

从终端打开 VSCode 帮助我检测到错误。消除了这些错误并成功构建。