c# - Entity Framework Core 添加迁移给出的值不能为空。 (参数 'connectionString')

Question

我是 .NET Core 新手，正在学习 Udemy 类(class)。我正在尝试启用迁移以代码优先，但我不断收到错误

Value cannot be null. (Parameter 'connectionString')

我做了一些研究，似乎大多数时候都是 appsetttings.json 文件中的 ConnectionStrings 拼写错误。然而，我已经检查了我的所有内容并尝试了几次复制/粘贴以确保我的拼写正确。要么是别的东西，要么是我看这个太多而忽略了一些东西。

应用程序设置.json

{
    "ConnectionStings": {
        "DbConnection": "Server=DAVIDPC\\SQLEXPRESS01;Database=dotnet-rpg;Trusted_Connection=true;MultipleActiveResultSets=true;"
    },
    "Logging": {
        "LogLevel": {
            "Default": "Information",
            "Microsoft": "Warning",
            "Microsoft.Hosting.Lifetime": "Information"
        }
    },
    "AllowedHosts": "*"
}

启动.cs

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.AddDbContext<DataContext>(x => x.UseSqlServer(Configuration.GetConnectionString("DbConnection")));
    services.AddControllers();
    services.AddAutoMapper(typeof(Startup));
    services.AddScoped<ICharacterService, CharacterService>();
}

Answer 1

在您的示例中，您拼写错误ConnectionStrings

 {
        "ConnectionStrings": {
            "DbConnection": "Server=DAVIDPC\\SQLEXPRESS01;Database=dotnet-rpg;Trusted_Connection=true;MultipleActiveResultSets=true;"
        },
        "Logging": {
            "LogLevel": {
                "Default": "Information",
                "Microsoft": "Warning",
                "Microsoft.Hosting.Lifetime": "Information"
            }
        },
        "AllowedHosts": "*"
    }