Net core AP層的變數設定

Net 8 AP層的變數設定

載入變數的順序

當Asp.net core 服務開啟時，會有載入的順序，越晚載入的變數，會蓋掉之前設定的變數

appsettings.{Enviroment}.json -> Environment variables -> Command-line argument ->other sources

使用appsettings.{Enviroment}.json，設定應用程式變數

 {
  "AppConfig": {
    "SmptIP": "gmail.com.tw",
    "SmptPort": "512"
  }
}

使用環境變數，設定應用程式變數

 set AppConfig__SmptIP=smpt.google.com
 set AppConfig__SmptPort=433

使用Command-line argument，設定應用程式變數

 F:\source\WebApplication1\WebApplication1\bin\>WebApplication1.exe --AppConfig:SmptIP="smpt.hotmail.com" --AppConfig:SmptPort=500
 

自我設定appsettings.json檔案路徑

Program.cs 加上AddJsonFile方式來讓保護環境參數檔案

builder.Configuration.AddJsonFile(@"E:\site.appsettings.json");

取得appsettings.{Enviroment}.json的方式

• (1) 設定建構子IConfiguration參數

 public WeatherForecastController(IConfiguration configuration)
 {
    _configuration = configuration;
 }

• (2) 設定IConfiguration參數

新增類別:AppSettingOptions

    public class AppSettingOptions
    {
        public const string Appsettings = "AppConfig";
        public required string Site { get; set; } = "www.example.com";
        public required int Port { get; set; } = 500;
    }

appsettings.json

 {
  "ConnectionStrings": {},
  "AppConfig": {
    "Site": "www.google.com.tw",
    "Port": 90
 }

WeatherForecastController.cs: 新增TestGet()方法

  [HttpGet("TestGet", Name = "TestGet")]
 
  public string TestGet() 
  {
      AppSettingOptions? appSettingOptions = _configuration.Get();

      return $"Site:{appSettingOptions?.Site}, Port:{appSettingOptions?.Port}"; 
  }

WeatherForecastController.cs: 新增TestGetValue()方法

 [HttpGet("TestGetValue", Name = "TestGetValue")]
 
 public string TestGetValue()
 {
     string? Site = _configuration.GetValue("AppConfig:Site");
     string? Port = _configuration.GetValue("AppConfig:Port");
 
     return $"Site:{Site}, Port:{Port}";
 }

• (3) 設定環境變數的方式

WeatherForecastController.cs: 新增TestGetEnv()方法

public string TestGetEnv()
{
    //第一種抓取環境變數的方法
    string? Port2  = System.Environment.GetEnvironmentVariable("SmptPort2");

    //第二種抓取環境變數的方法
    string? Site = _configuration["SmptIP"];
    string? Port = _configuration["SmptPort"]; 

    return $"Site:{Site}, Port:{Port}, Port2:{Port2}";
}

結果:Site:gmail333.com.tw, Port:, Port2:test

取得appsettings.json 檢查變數去卡控

• AppSettingOptions :加上檢查機制

    public class AppSettingOptions
    {
        public const string Appsettings = "AppConfig";

        public required string Site { get; set; } = "www.example.com";

        [RegularExpression("^\\d{4}$")]
        public required int Port { get; set; } ;
    }

• appsettings.json : 將port改成字串，後面希望啟動時可以檢查出錯誤

{
  "AppConfig": {
    "Site": "www.google.com.tw",
    "Port": "test"
  }
}

• Programs.cs

//註冊AppSettingOptions時，可以檢查屬性有沒有符合RegularExpression

builder.Services.AddOptions()
    .Bind(builder.Configuration.GetSection(AppSettingOptions.Appsettings))
    .ValidateDataAnnotations()
    .ValidateOnStart();

出現錯誤，訊息告訴你'AppConfig:Port' to type 'System.Int32，應該是整數

• WeatherForecastController.cs

 
  private readonly ILogger _logger;
  private readonly IConfiguration _configuration;
  private readonly IOptions _options;
  public WeatherForecastController(ILogger logger,
      IConfiguration configuration,
      IOptions options)
  {
      _logger = logger;
      _configuration = configuration;
      this._options = options;
  }

 [HttpGet("TestGet", Name = "TestGet")]
 public string TestGet() 
 {
     return $"Site:{_options?.Value.Site}, Port:{_options?.Value.Port}"; 
 }

可以看到將Port 改成8080就成功