如何从appsettings获取值。在控制台应用程序中使用json。净核心？

Question

我正在创建一个控制台应用程序使用。NET Core 3.1和我想有一个app设置json加载所有的环境，路径，变量，...在执行开始，然后从其他库类获取值。我创建了一个设置类，其中的数据包含在应用设置json中。这是我已经在教程中找到的，但我无法获得任何价值。

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

            Configuration = builder.Build();
        }

        public IConfiguration Configuration { get; }

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

//Settings.cs
 public class Settings
    {
        public ConnectionStrings ConnectionStrings { get; set; }
        public Logging Logging { get; set; }
        public AppSettings AppSettings { get; set; }
    ...

//A class to use it in other lib
 public class Extractor
    {
        private readonly IConfiguration _configuration;

        public Extractor(IConfiguration configuration) : this()
        {
            _configuration = configuration;
            Init();
        }

        public void Init()
        {
            // Extractor:Min is a variable included in appsettings.json
            Min = _configuration.GetValue<int>("Extractor:Min")
                                  
        }

因为我不知道如何初始化所有东西，所以我不能做一个正确的主。。。我错过了什么？我想我一直在为这么简单的事情兜圈子。提前谢谢！注意：我需要从另一个库类中获取这些变量，而不是在Main中。我不知道如何在其他类中初始化“配置”以使用它。谢谢

Answer 1

http://www.techtutorhub.com/article/how-to-read-appsettings-json-configuration-file-in-dot-net-core-console-application/83

帮帮忙！

1. 应用设置。json（添加appsettings.json后，转到属性并将文件标记为copy to out目录）

{
  "ConnectionString": "Server=localhost;Database=tempDB;Uid=<dbUserName>;Pwd=<dbPassword>",
  "Smtp": {
    "Host": "smtp.gmail.com",
    "Port": "587",
    "Username": "<YourGmailUserName>",
    "Password": "<YourGmailPassword>",
    "From": "Your Name"
  }
}

2.package需要

dotnet add package Microsoft.Extensions.Configuration
dotnet add package Microsoft.Extensions.Configuration.Json

using System; 
using Microsoft.Extensions.Configuration;

    class Program
        {
            static void Main(string[] args)
            {
                  var builder = new ConfigurationBuilder()
                   .AddJsonFile($"appsettings.json", true, true);
    
                var config = builder.Build();
                var connectionString = config["ConnectionString"];
                var emailHost = config["Smtp:Host"];
                Console.WriteLine($"Connection String is: {connectionString}");
                Console.WriteLine($"Email Host is: {emailHost}");
                Console.ReadLine();
            }
        }

Answer 2

我也有同样的问题。NET Core和我发现这个解决方案运行良好：

    {
      "App": 
      {
        "LoginCredentials": 
        {
           "ClientId": "xxx",
           "ClientSecret": "xxx",
           "TenantId": "xxx"
        },
        "DataBase": 
        {
            "PathToDatabases": "xxx"
        },
        "General": 
        {
           "PathToLogFiles": "xxx"
        }
      }

    }

1. 我创建了一个类AppSettingsHandler。cs

    public class AppSettingsHandler
    {
        private string _filename;
        private AppSettings _config;

        public AppSettingsHandler(string filename)
        {
            _filename = filename;
            _config = GetAppSettings();
        }

        public AppSettings GetAppSettings()
        {
            var config = new ConfigurationBuilder()
               .SetBasePath(AppContext.BaseDirectory)
               .AddJsonFile(_filename, false, true)
               .Build();

            return config.GetSection("App").Get<AppSettings>();
        }
    }

    public class AppSettings
    {
        public LoginCredentialsConfiguration LoginCredentials { get; set; }
        public DatabaseConfiguration DataBase { get; set; }
        public GeneralConfiguration General { get; set; }
    }

每个包含的子类都有一个模型类，我这里只举一个例子：

    public class LoginCredentialsConfiguration
    {
        public string ClientId { get; set; }
        public string ClientSecret { get; set; }
        public string TenantId { get; set; }
    }

            var aH = new AppSettingsHandler("appsettings.json");
            var aS = aH.GetAppSettings();
            var myPath = aS.DataBase.PathToDatabases;

当然，你可以调整代码，使其符合你的需求，也就是说，你必须定义自己的类和子类，当然你可以扩展AppSettingsHandler。通过获取应用程序设置的其他部分来实现cs。json。

Answer 3

您的示例混合了一些ASP NET核心方法，这些方法希望您的代码能够被托管。为了从JSON配置中最低限度地获得选项或设置的问题，请考虑以下内容：

Aconfig。json文件，设置为“复制到输出目录”，以便将其包含在构建中：

{
  "MyFirstClass": {
    "Option1": "some string value",
    "Option2": 42
  },
  "MySecondClass": {
    "SettingOne": "some string value",
    "SettingTwo": 42
  }
}

以下方法将从JSON文件加载内容，然后将内容绑定到两个强类型的选项/设置类，这比逐个值要简洁得多：

using System;
using System.IO;
using Microsoft.Extensions.Configuration;

// NuGet packages:
// Microsoft.Extensions.Configuration.Binder
// Microsoft.Extensions.Configuration.Json

namespace SampleConsole
{
    class Program
    {
        static void Main(string[] args)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("config.json", optional: false);

            IConfiguration config = builder.Build();

            var myFirstClass = config.GetSection("MyFirstClass").Get<MyFirstClass>();
            var mySecondClass = config.GetSection("MySecondClass").Get<MySecondClass>();
            Console.WriteLine($"The answer is always {myFirstClass.Option2}");
        }
    }

    public class MyFirstClass
    {
        public string Option1 { get; set; }
        public int Option2 { get; set; }
    }

    public class MySecondClass
    {
        public string SettingOne { get; set; }
        public int SettingTwo { get; set; }
    }
}