c# - 访问 ASP.NET Core 中的配置选项 : options pattern

Question

我有一个 ASP.NET Core 应用程序。我尝试使用选项模式，但它似乎不起作用。

我有以下 appsettings.json:

{
    "ConnectionStrings": {
        "MyTablesConnectionString": "Default[...];EndpointSuffix=core.windows.net"
    },

    "Logging": { "IncludeScopes": false, "LogLevel": { "Default": "Warning" }  }
}

下面的 ConnectionStrings 类

public class ConnectionStrings {
    public ConnectionStrings()  {
        MyTablesConnectionString = "default value";
    }

    public string MyTablesConnectionString { get; set; }
}

这是我的Startup.cs

public Startup(IHostingEnvironment env)
{
    var builder = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
        .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true)
        .AddEnvironmentVariables();
    Configuration = builder.Build();

    // HERE IS THE GOOD VALUE !!!!!!!!
    Debug.WriteLine($"Connection string is:{Configuration["ConnectionStrings:MyTablesConnectionString"]}");
}

public void ConfigureServices(IServiceCollection services)
{
    // Adds services required for using options.
    services.AddOptions();
    // Register the IConfiguration instance which "ConnectionStrings" binds against.
    services.Configure<ConnectionStrings>(Configuration);

    // Add framework services.
    services.AddMvc();            
}

但是，在带有以下 Controller 的开发机器上使用它时

private readonly ConnectionStrings azureConnectionString;
public HelloWorldController(IOptions<ConnectionStrings> optionsAccessor)
{
    // HERE IS THE "DEFAULT" VALUE ?!!!!!!!!
    azureConnectionString = optionsAccessor.Value;            
}

我看到使用的是“默认值”而不是 json 文件中的值(无效的)。我错过了什么吗？

Answer 1

您需要像这样绑定(bind) ConnectionStrings 部分:

services.Configure<ConnectionStrings>(Configuration.GetSection("ConnectionStrings"));

目前它期望从您的类中找到属性“ConnectionStrings”或“Logging”，因为您正在绑定(bind)根。