c# - Blazor 服务器实体框架：值不能为空。（参数“连接字符串”）

Question

我创建了一个 blazor 服务器应用程序，并试图将其连接到我的 mysql 数据库。我已经在启动内部设置了连接字符串和服务，但是当我尝试添加初始迁移时，Add-Migration init -Context ApplicationDbContext我得到了错误：

Value cannot be null. (Parameter 'connectionString')

我的启动看起来像这样：

        public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        string identityConnectionString = Configuration.GetConnectionString("IdentityConnection");
        string dbConnectionString = Configuration.GetConnectionString("DebateBuddyConnection");

        services.AddDbContext<ApplicationDbContext>(options =>
        {
            options.UseMySql(identityConnectionString, ServerVersion.AutoDetect(identityConnectionString));
            options.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking);
        });

        services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
            .AddEntityFrameworkStores<ApplicationDbContext>();

        services.AddEntityFrameworkMySql().AddDbContext<BuddyDbContext>(options => 
        {
            options.UseMySql(dbConnectionString, ServerVersion.AutoDetect(dbConnectionString));
            options.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking);
        });       

        services.AddRazorPages();
        services.AddServerSideBlazor();
        services.AddBlazoredModal();
        services.AddSingleton<AppData>();
        services.AddScoped<AuthenticationStateProvider, RevalidatingIdentityAuthenticationStateProvider<IdentityUser>>();
        services.AddScoped<ClipboardService>();
        services.AddScoped<SMTPSender>();
        services.AddDatabaseDeveloperPageExceptionFilter();
    }

还有我的 appsettings.json：

{
"ConnectionStrings": {
    "IdentityConnection": "Server=ipaddress; Database=dbname; Uid=username; Pwd=password;Trusted_Connection=True;MultipleActiveResultSets=true",
    "DebateBuddyConnection": "Server=ipaddress; Database=dbname; Uid=username; Pwd=password;Trusted_Connection=True;MultipleActiveResultSets=true"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}

如果我在运行应用程序时设置断点，我可以看到我的两个变量：

 string identityConnectionString = Configuration.GetConnectionString("IdentityConnection");
 string dbConnectionString = Configuration.GetConnectionString("DebateBuddyConnection");

都包含来自 appsettings.json 的连接字符串

如果我运行Add-Migration init -Context ApplicationDbContext或Add-Migration init -Context BuddyDbContext

因为我的数据库是 MySQL 数据库，所以我使用的是 pomelo.EntityFrameworkCore.MySql nuget 包 v5.0.0。

编辑：

如果我手动输入字符串，我也会得到同样的错误：

 services.AddDbContext<ApplicationDbContext>(options =>
        {
            options.UseMySql("Server=ipaddress; Database=dbname; Uid=username; Pwd=password;Trusted_Connection=True;MultipleActiveResultSets=true", ServerVersion.AutoDetect("Server=ipaddress; Database=database; Uid=username; Pwd=password;Trusted_Connection=True;MultipleActiveResultSets=true"));
            options.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking);
        });

或喜欢

 string identityConnectionString = "Server=ipaddress; Database=dbname; Uid=username; Pwd=password;Trusted_Connection=True;MultipleActiveResultSets=true";
        
        services.AddDbContext<ApplicationDbContext>(options =>
        {
            options.UseMySql(identityConnectionString, ServerVersion.AutoDetect(identityConnectionString));
            options.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking);
        });

标签： c#entity-framework-coreblazorentity-framework-migrationsblazor-server-side