在 Console 取得 appsetings.json

var config = new ConfigurationBuilder()
    .AddJsonFile("appSettings.json", optional: true)
    .AddJsonFile($"appSettings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT")}.json", optional: true)
    .Build();

var connectionString = config.GetConnectionString("DefaultConnection");

var logPath = config.GetSection("LogPath").Value;

var mailSetting = config.GetSection("MailSettings").Get<MailSettingModel>();