ASP.NET Core 5搭配EF Core脚手架生成API控制器报连接字符串为空错误

该报错由两处拼写错误导致连接字符串读取为空：

• Startup.cs中读取连接字符串的键名拼写错误：代码中填写的键名为DefaultConection，比appsettings.json中定义的DefaultConnection少了字母n，导致读取配置返回null
• appsettings.json中的连接字符串存在语法错误：Initial,Catalog中间多写了逗号，正确格式为Initial Catalog

修正后的配置代码 #

1. appsettings.json #

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "DefaultConnection":"Data Source=DESKTOP-THJSEM4;Initial Catalog=M_VPSA_V3;Integrated Security=True"
  }
}

2. Startup.cs ConfigureServices方法 #

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers();
    services.AddDbContext<M_VPSA_V3Context>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "API_MOBEXX", Version = "v1" });
            });
}

修正后重新编译项目，再执行脚手架生成API控制器操作即可正常运行。

内容的提问来源于stack exchange，提问作者Roman Sadowski