System.ArgumentNullException：'值不能为null。 （参数'connectionString'）'

Question

这是appsetting.json文件

{
  "Connection Strings": {
    "EmployeeDBConnection": "server=(localhost)\\SQLEXPRESS ; database=EmployeeDB; Trusted_Connection =true"
  },


  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },


  "AllowedHosts": "*",
  "MyKey": "Value of MYKey from appsettings.json"

}

这是startup.cs文件

namespace EmployeeManagement
{
    public class Startup
    {
        private IConfiguration _config;

      
        public Startup(IConfiguration config)
        {
            _config = config;

        }
        
        public void ConfigureServices(IServiceCollection services)
        {
            
            services.AddScoped<IEmployeeRepository, SQLEmployeeRepository>();
            services.AddControllersWithViews();

            services.AddDbContextPool<AppDbContext>(options => options.UseSqlServer(_config.GetConnectionString("EmployeeDBConnection")));
       

        }

        // 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();
            }

            app.UseStaticFiles();
            app.UseMvcWithDefaultRoute();

            app.Run(async (context) =>
            {
               
                await context.Response.WriteAsync("Hello World");
            });


        }
     
    }

}

我检查了“连接字符串”最后是否有s， 更改了连接字符串在appsetting.json文件中的位置 我将整个ConnectionString放在这里，而不是只在Startup.cs的Configuration.GetConnectionString（）中写入连接字符串的名称。 我仍然遇到此错误。

Answer 1

您的密钥"Connection Strings"包含空格。更改为"ConnectionStrings"以实现预期的行为

Answer 2

"Connection Strings"与您的参数"connectionStrings"不匹配。您需要在appsettings.cs中进行更改。也可能需要用"connectionString"代替，您的措辞让我有些困惑。无论如何，您的程序都在寻找"connectionString"，而不是"Connection Strings"。