不知道我在这里缺少什么，但我无法从我的.net核心应用程序中的appsettings.json获取值。我的appsettings.json为：
{
"AppSettings": {
"Version": "One"
}
}
启动：
public class Startup
{
private IConfigurationRoot _configuration;
public Startup(IHostingEnvironment env)
{
_configuration = new ConfigurationBuilder()
}
public void ConfigureServices(IServiceCollection services)
{
//Here I setup to read appsettings
services.Configure<AppSettings>(_configuration.GetSection("AppSettings"));
}
}
模型：
public class AppSettings
{
public string Version{ get; set; }
}
控制器：
public class HomeController : Controller
{
private readonly AppSettings _mySettings;
public HomeController(IOptions<AppSettings> settings)
{
//This is always null
_mySettings = settings.Value;
}
}
_mySettings总是空的。这里有什么我想念的吗？
感谢@Kirk指出我不应该假设它是.NET Core 2.0！
你不需要在IConfiguration构造函数中使用新的Startup。其实施将由DI系统注入。
// Program.cs
public class Program
{
public static void Main(string[] args)
{
BuildWebHost(args).Run();
}
public static IWebHost BuildWebHost(string[] args) =>
WebHost.CreateDefaultBuilder(args)
.UseStartup<Startup>()
.Build();
}
// Startup.cs
public class Startup
{
public IHostingEnvironment HostingEnvironment { get; private set; }
public IConfiguration Configuration { get; private set; }
public Startup(IConfiguration configuration, IHostingEnvironment env)
{
this.HostingEnvironment = env;
this.Configuration = configuration;
}
}
您需要告诉Startup加载appsettings文件。
// Program.cs
public class Program
{
public static void Main(string[] args)
{
var host = new WebHostBuilder()
.UseKestrel()
.UseContentRoot(Directory.GetCurrentDirectory())
.UseIISIntegration()
.UseStartup<Startup>()
.UseApplicationInsights()
.Build();
host.Run();
}
}
//Startup.cs
public class Startup
{
public IConfigurationRoot Configuration { get; private set; }
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();
this.Configuration = builder.Build();
}
...
}
您可以通过多种方式从应用设置中获取您配置的值：
ConfigurationBuilder.GetValue<T>的简单方法让我们说你的appsettings.json看起来像这样：
{
"ConnectionStrings": {
...
},
"AppIdentitySettings": {
"User": {
"RequireUniqueEmail": true
},
"Password": {
"RequiredLength": 6,
"RequireLowercase": true,
"RequireUppercase": true,
"RequireDigit": true,
"RequireNonAlphanumeric": true
},
"Lockout": {
"AllowedForNewUsers": true,
"DefaultLockoutTimeSpanInMins": 30,
"MaxFailedAccessAttempts": 5
}
},
"Recaptcha": {
...
},
...
}
您可以将整个配置注入控制器/类的构造函数（通过IConfiguration），并使用指定的键获取所需的值：
public class AccountController : Controller
{
private readonly IConfiguration _config;
public AccountController(IConfiguration config)
{
_config = config;
}
[AllowAnonymous]
public IActionResult ResetPassword(int userId, string code)
{
var vm = new ResetPasswordViewModel
{
PasswordRequiredLength = _config.GetValue<int>(
"AppIdentitySettings:Password:RequiredLength"),
RequireUppercase = _config.GetValue<bool>(
"AppIdentitySettings:Password:RequireUppercase")
};
return View(vm);
}
}
如果您只需要应用程序设置中的一个或两个值，ConfigurationBuilder.GetValue<T>的效果很好。但是，如果您想从应用程序设置中获取多个值，或者您不想在多个位置对这些键字符串进行硬编码，则可能更容易使用“选项模式”。选项模式使用类来表示层次结构/结构。
要使用选项模式：
IOptions<T>注入要获取值的控制器/类的构造函数中您可以定义具有需要与应用设置中的键完全匹配的属性的类。该类的名称不必与应用程序设置中的部分名称匹配：
public class AppIdentitySettings
{
public UserSettings User { get; set; }
public PasswordSettings Password { get; set; }
public LockoutSettings Lockout { get; set; }
}
public class UserSettings
{
public bool RequireUniqueEmail { get; set; }
}
public class PasswordSettings
{
public int RequiredLength { get; set; }
public bool RequireLowercase { get; set; }
public bool RequireUppercase { get; set; }
public bool RequireDigit { get; set; }
public bool RequireNonAlphanumeric { get; set; }
}
public class LockoutSettings
{
public bool AllowedForNewUsers { get; set; }
public int DefaultLockoutTimeSpanInMins { get; set; }
public int MaxFailedAccessAttempts { get; set; }
}
然后你需要在启动时在ConfigureServices()中注册这个配置实例：
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
...
namespace DL.SO.UI.Web
{
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
...
var identitySettingsSection =
_configuration.GetSection("AppIdentitySettings");
services.Configure<AppIdentitySettings>(identitySettingsSection);
...
}
...
}
}
最后，在想要获取值的控制器/类上，需要通过构造函数注入IOptions<AppIdentitySettings>：
public class AccountController : Controller
{
private readonly AppIdentitySettings _appIdentitySettings;
public AccountController(IOptions<AppIdentitySettings> appIdentitySettingsAccessor)
{
_appIdentitySettings = appIdentitySettingsAccessor.Value;
}
[AllowAnonymous]
public IActionResult ResetPassword(int userId, string code)
{
var vm = new ResetPasswordViewModel
{
PasswordRequiredLength = _appIdentitySettings.Password.RequiredLength,
RequireUppercase = _appIdentitySettings.Password.RequireUppercase
};
return View(vm);
}
}
添加David Liang对Core 2.0的回答 -
qazxsw poi文件链接到qazxsw poi变量。
appsettings.json可以设置为任何值，但框架支持三个值：ASPNETCORE_ENVIRONMENT，ASPNETCORE_ENVIRONMENT和Development。如果未设置Staging，则默认为Production。
对于这三个值，这些appsettings.ASPNETCORE_ENVIRONMENT.json文件支持开箱即用 - ASPNETCORE_ENVIRONMENT，Production和appsettings.Staging.json
以上三个应用程序设置json文件可用于配置多个环境。
示例 - appsettings.Development.json
appsettings.Production.json使用appsettings.Staging.json检索任何配置值。
{
"Logging": {
"IncludeScopes": false,
"LogLevel": {
"System": "Information",
"Microsoft": "Information"
}
},
"MyConfig": "My Config Value for staging."
}
只需创建一个AnyName.cs文件并粘贴以下代码即可。
Configuration["config_var"]必须用您的文件名替换YouAppSettingFile.json文件名。 您的.json文件应如下所示。
public class Startup
{
public Startup(IHostingEnvironment env, IConfiguration config)
{
Environment = env;
Configuration = config;
var myconfig = Configuration["MyConfig"];
}
public IConfiguration Configuration { get; }
public IHostingEnvironment Environment { get; }
}
现在你可以使用它了。 不要忘记在您要使用的班级中添加参考。
using System;
using System.IO;
using Microsoft.Extensions.Configuration;
namespace Custom
{
static class ConfigurationManager
{
public static IConfiguration AppSetting { get; }
static ConfigurationManager()
{
AppSetting = new ConfigurationBuilder()
.SetBasePath(Directory.GetCurrentDirectory())
.AddJsonFile("YouAppSettingFile.json")
.Build();
}
}
}
用于检索值的代码。
{
"GrandParent_Key" : {
"Parent_Key" : {
"Child_Key" : "value1"
}
},
"Parent_Key" : {
"Child_Key" : "value2"
},
"Child_Key" : "value3"
}
我想最简单的方法是DI。进入Controller的一个例子。
using Custom;
在Startup类的构造函数中，您可以使用注入的IConfiguration对象访问appsettings.json和许多其他设置：
Startup.cs构造函数
string value1 = ConfigurationManager.AppSetting["GrandParent_Key:Parent_Key:Child_Key"];
string value2 = ConfigurationManager.AppSetting["Parent_Key:Child_Key"];
string value3 = ConfigurationManager.AppSetting["Child_Key"];
appsettings.json的内容
// StartUp.cs
public void ConfigureServices(IServiceCollection services)
{
...
// for get appsettings from anywhere
services.AddSingleton(Configuration);
}
public class ContactUsController : Controller
{
readonly IConfiguration _configuration;
public ContactUsController(
IConfiguration configuration)
{
_configuration = configuration;
// sample:
var apiKey = _configuration.GetValue<string>("SendGrid:CAAO");
...
}
}
public Startup(IConfiguration configuration)
{
Configuration = configuration;
//here you go
var myvalue = Configuration["Grandfather:Father:Child"];
}
public IConfiguration Configuration { get; }
就我而言，在Configuration对象上使用Bind（）方法很简单。然后在DI中将对象添加为单例。
{
"Grandfather": {
"Father": {
"Child": "myvalue"
}
}
Instruction对象可以根据需要复杂化。
public static void GetSection()
{
Configuration = new ConfigurationBuilder()
.SetBasePath(env.ContentRootPath)
.AddJsonFile("appsettings.json")
.Build();
string BConfig = Configuration.GetSection("ConnectionStrings")["BConnection"];
}