Asp.net core 学习笔记 ( Configuration 配置 )

更新 2020-01-11

IOptions 默认值

  var config = ServiceProvider.GetService<IOptions<UploadedFilesPathOptions>>();

即便我们忘了 setup (下图), 我们依然会拿到一个对象(上图), 里面的 value 是 default value

services.Configure<UploadedFilesPathOptions>(Configuration.GetSection("UploadedFilesPath"));

https://blog.wille-zone.de/post/is-ioptions-t-bad/

可能这个行为不是很好理解，因为一般上 DI 如果没有 provide, inject 时是返回 null.

文章说如果你不喜欢可以使用 IOption Factory 改掉这个行为...

更新 : 2019-05-05

name options

 services.Configure<SlackApiSettings>("Dev", Configuration.GetSection("SlackApi:DevChannel")); 

第一个变量是名字, 然后如下获取

    public SlackNotificationService(IOptionsSnapshot<SlackApiSettings> options)
    {
        SlackApiSettings devSettings = options.Get("Dev");
    }

identity 就是用了这个手法在 CookieAuthenticationOptions 上哦.

更新 : 2019-05-03

set options in startup config

services.Configure<BusinessOptions>(Configuration.GetSection("Email")) // set from appsetting
        .Configure<BusinessOptions>(options => { add more
            options.Price = ;
            options.Name = "zhu ba jie";
        });

参考 : https://cnblogs.com/nianming/p/7083964.html

配置写在 appsettings.json 里头

比如

{
  "object": {
    "prop": "value"
  },
  "array": [
    { "prop": "value" }
  ],
  "businessConfig": {
    "paypalEmail" : "hengkeat87@gmail.com"
  }
}

startup.cs

namespace Project
{
    public class BusinessConfig
    {
        public string paypalEmail { get; set; }
    }

    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            this.configuration = configuration;
        }

        public IConfiguration configuration { get; }
        public void ConfigureServices(IServiceCollection services)
        {
            // 各种获取 config 的方式
            var value = configuration["object:prop"];
            value = configuration["array:0:prop"];
            var obj = configuration.GetSection("object");
            value = obj["prop"];

            // 绑定类型
            string stringValue = configuration.GetValue<string>("object:prop");
            BusinessConfig businessConfig = configuration.GetSection("businessConfig").Get<BusinessConfig>();

            // 注册到 service 让 control 可以注入
            services.Configure<BusinessConfig>(configuration.GetSection("businessConfig"));
        }
    }
}

controller.cs

public class HomeController : Controller
{
    private readonly BusinessConfig businessConfig;
    public HomeController(

        // IOptionsSnapshot 对比 IOptions 特色是更新 config file 时, snapshot 能获取新值, 很奇怪, 不是说 snapshot 吗 ? 怎么反而可以获取到新值...纳闷
        IOptionsSnapshot<BusinessConfig> businessConfigOptionsAccessor, // 能
        // IOptions<BusinessConfig> businessConfigOptionsAccessor // 不能
    )
    {
        businessConfig = businessConfigOptionsAccessor.Value;
    }

    public IActionResult Index()
    {
        string paypalEmail = businessConfig.paypalEmail;
        return View();
    }
}

Configuration 是可以随时 set 的. 要使用 options 获取 config 就一定要执行 services.Configure.

由于 key-vault 只能放在第一层，所以我们通常需要额外功夫 set 进去.

Configuration["email:password"] = Configuration["key-vault-secret-email-password"];
services.Configure<Email>(Configuration.GetSection("email"));