C# 但是，通过dotnet run运行终端的ion似乎可以在生产环境中运行应用程序。将终端中使用的环境更改为开发（export-ASPNETCORE\u-environment=development）后，一切正常。您是从与项目相同的目录中使用dotnet r

---

但是，通过

dotnet run

运行终端的ion似乎可以在生产环境中运行应用程序。将终端中使用的环境更改为开发（

export-ASPNETCORE\u-environment=development

）后，一切正常。

您是从与项目相同的目录中使用

dotnet run

，还是从不同的目录中使用它？（例如，

dotnet运行-p path/to.csproj

）是的，我使用的dotnet运行来自与项目源相同的目录。如果我从代码中删除DbSeeder，它就可以正常工作。因为对

UseNpgsql（）

的调用抛出后，连接字符串似乎无法从配置中读取（这是在解析

DbSeeder

时传递执行的，因为它可能取决于上下文）

Unhandled Exception: System.Exception: Could not resolve a service of type 'OpenGameListApp.Data.DbSeeder' for the parameter 'dbSeeder' of method 'Configure' on type 'OpenGameListApp.Startup'. ---> System.ArgumentNullException: Value cannot be null.
Parameter name: connectionString
   at Microsoft.EntityFrameworkCore.Utilities.Check.NotEmpty(String value, String parameterName)
   at Microsoft.EntityFrameworkCore.NpgsqlDbContextOptionsExtensions.UseNpgsql(DbContextOptionsBuilder optionsBuilder, String connectionString, Action`1 NpgsqlOptionsAction)
   at OpenGameListApp.Startup.<ConfigureServices>b__4_0(DbContextOptionsBuilder options) in /home/noam/projects/dotnet/OpenGameListApp/src/Startup.cs:line 43
   at Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.DbContextOptionsFactory[TContext](IServiceProvider applicationServiceProvider, Action`2 optionsAction)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.<>c__DisplayClass16_0.<RealizeService>b__0(ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.AspNetCore.Hosting.Internal.ConfigureBuilder.Invoke(Object instance, IApplicationBuilder builder)
   --- End of inner exception stack trace ---
   at Microsoft.AspNetCore.Hosting.Internal.ConfigureBuilder.Invoke(Object instance, IApplicationBuilder builder)
   at Microsoft.AspNetCore.Hosting.ConventionBasedStartup.Configure(IApplicationBuilder app)
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()
   at Microsoft.AspNetCore.Hosting.WebHostBuilder.Build()
   at OpenGameListApp.Program.Main(String[] args) in /home/noam/projects/dotnet/OpenGameListApp/src/Program.cs:line 15

public void ConfigureServices(IServiceCollection services)
{
    // Add framework services
    services.AddMvc();

    // Add entity framework
    services.AddEntityFrameworkNpgsql()
        .AddDbContext<ApplicationDbContext>(options => 
            options.UseNpgsql(Configuration["Data:DefaultConnection:ConnectionString"]));    

    // Add database seeder
    services.AddSingleton<DbSeeder>();
}

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, DbSeeder dbSeeder)
{
    // Add logger
    loggerFactory.AddConsole(Configuration.GetSection("Logging"));
    loggerFactory.AddDebug();

    // Rewrite all routing urls including the root one to the index.html file by adding the following rules
    var rewriteOptions = new RewriteOptions().AddIISUrlRewrite(env.ContentRootFileProvider, "rewrite-rules.xml");

    // Add iis url rewrite features to kestrel            
    // Note: the app.UseRewriter method must be called before app.UseDefaultFiles and app.UseStaticFiles
    app.UseRewriter(rewriteOptions);

    // In order for your Web app to serve a default page without the user having to fully qualify the URI,
    app.UseDefaultFiles();

    // Enable service of static files in wwwroot folder
    app.UseStaticFiles(new StaticFileOptions()
    {
        OnPrepareResponse = (context) => 
        {
            // Disable caching for all static files
            context.Context.Response.Headers["Cache-Control"] = Configuration["StaticFiles:Headers:Cache-Control"];
            context.Context.Response.Headers["Pragma"] = Configuration["StaticFiles:Headers:Pragma"];
            context.Context.Response.Headers["Expires"] = Configuration["StaticFiles:Headers:Expires"];
        }
    });

    // Enable the use of asp.net mvc framework
    app.UseMvc();     

    // Initialize auto mapper
    Mapper.Initialize(cfg => cfg.CreateMap<Item, ItemViewModel>());

    // Seed database
    dbSeeder.SeedIt();               
}