ConfigurationBuilder尚未定义AddJson

Question

我尝试通过执行后续步骤来使用json文件中的连接字符串

Json文件

{
    "ConnectionStrings": {
        "PlatformDatabase": "Server=xxxx\\SQLEXPRESS;Database=xxxx;Trusted_Connection=True;"
    }
}

访问json

var builder = new ConfigurationBuilder()
              .SetBasePath(System.AppContext.BaseDirectory)
              .AddJsonFile("appsettings.json",
                  optional: true,
                  reloadOnChange: true);

Configuration = builder.Build();

optionsBuilder.UseSqlServer(Configuration.GetConnectionString("PlatformDatabase"));

  

错误： ConfigurationBuilder不包含   AddJsonFile。

以前有人有这个问题吗？我尝试搜索它，但我找到的所有解决方案现在都不起作用（我认为版本2）。

编辑

请注意。我创建了.Net Core 2.0控制台应用程序

Answer 1

安装nuget包

解决了这个问题

  

Microsoft.Extensions.Configuration.Json

Answer 2

您无需在ASP.NET Core 2中明确添加appsettings.json。

您只需要Startup.cs -

中的以下内容

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

public IConfiguration Configuration { get; }

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(
       Configuration.GetConnectionString("PlatformDatabase")));

    ...
    services.AddMvc();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    ...
}

<强> Program.cs的

public class Program
{
    public static void Main(string[] args)
    {
        BuildWebHost(args).Run();
    }

    public static IWebHost BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>()
            .Build();
}

另一种方法

您在 DI容器中将 IConfiguration 注册为 Singleton / strong>，然后将其注入您的DBContext构造函数。然后在OnConfiguring方法中获取连接字符串。

public class Startup
{
    public Startup(IConfiguration config)
    {
        _config = config;
    }

    private IConfiguration _config;

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton(_config);
        services.AddDbContext<YOUR_DB_Context>(ServiceLifetime.Scoped);

        ...

        services.AddMvc();
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        ...
    }
}

<强> YOUR_DB_Context.cs

public class YOUR_DB_Context : IdentityDbContext OR DbContext
{
    private IConfiguration _config;

    public YOUR_DB_Context(DbContextOptions options, IConfiguration config)
        : base(options)
    {
        _config = config;
    }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        ...
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        base.OnConfiguring(optionsBuilder);

        optionsBuilder.UseSqlServer(_config["Data:PlatformDatabase"]);
    }
}