Question

我正在尝试使用迁移将我的 ASP.NET Core 网站连接到数据库。我正在使用命令

Scaffold-DbContext "Data Source=localhost;Initial Catalog=BlogDB;Integrated Security=True" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models

生成模型等。但是我在运行命令时出现以下错误：

<块引用>

缺少必需的参数''

如果需要，启动类只是当前的标准模板：

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace Personal_Blog
{
    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.AddControllersWithViews();

        }

        // 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("/Home/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.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

问题的一个例子是：

PM> Scaffold-DbContext "Data Source=localhost;Initial Catalog=BlogDB;Integrated Security=True" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -Verbose
Using project 'Personal Blog'.
Using startup project 'Personal Blog'.
Build started...
Build succeeded.
C:\Program Files\dotnet\dotnet.exe exec --depsfile "D:\Code\Personal\Personal Blog\Personal Blog\Personal Blog\bin\Debug\netcoreapp3.1\Personal Blog.deps.json" --additionalprobingpath C:\Users\samh\.nuget\packages --additionalprobingpath "C:\Program Files\dotnet\sdk\NuGetFallbackFolder" --runtimeconfig "D:\Code\Personal\Personal Blog\Personal Blog\Personal Blog\bin\Debug\netcoreapp3.1\Personal Blog.runtimeconfig.json" C:\Users\samh\.nuget\packages\microsoft.entityframeworkcore.tools\6.0.0-preview.1.21102.2\tools\netcoreapp2.0\any\ef.dll dbcontext scaffold "Data Source=localhost;Initial Catalog=BlogDB;Integrated Security=True" Microsoft.EntityFrameworkCore.SqlServer --json --output-dir Models --verbose --no-color --prefix-output --assembly "D:\Code\Personal\Personal Blog\Personal Blog\Personal Blog\bin\Debug\netcoreapp3.1\Personal Blog.dll" --startup-assembly "D:\Code\Personal\Personal Blog\Personal Blog\Personal Blog\bin\Debug\netcoreapp3.1\Personal Blog.dll" --project-dir "D:\Code\Personal\Personal Blog\Personal Blog\Personal Blog\\" --language C# --working-dir "D:\Code\Personal\Personal Blog\Personal Blog" --root-namespace Personal_Blog
Microsoft.EntityFrameworkCore.Tools.CommandException: Missing required argument '<PROVIDER>'.
   at Microsoft.EntityFrameworkCore.Tools.Commands.DbContextScaffoldCommand.Validate()
   at Microsoft.EntityFrameworkCore.Tools.Commands.CommandBase.<>c__DisplayClass0_0.<Configure>b__0(String[] args)
   at Microsoft.DotNet.Cli.CommandLine.CommandLineApplication.Execute(String[] args)
   at Microsoft.EntityFrameworkCore.Tools.Program.Main(String[] args)
Missing required argument '<PROVIDER>'.

有人能告诉我我遗漏了什么吗？

非常感谢。

Answer 1

这也发生在我身上。我意识到我已经为 EF 安装了预览版 (6.0) 包，因此我将它们降级到最新的稳定版本。但是我仍然遇到同样的错误。

重新启动 Visual Studio 后，Scaffold-DbContext 命令工作正常。

实体框架核心缺少参数“提供者”

1 个答案: