将配置绑定到 .NET Core 2.0 中的对象图
Binding a configuration to an object graph in .NET Core 2.0
我正在制作 .NET Core 2.0 应用程序，我需要对其进行配置。我正在查看 this documentation，似乎在 .NET Core 1.0 中你可以这样做：
var appConfig = new AppSettings();
config.GetSection("App").Bind(appConfig);
在 .NET Core 1.1 中你可以这样做：
var appConfig = config.GetSection("App").Get<AppSettings>();
但 .NET Core 2.0 中不存在 Bind 和 Get。实现这一目标的新方法是什么？
谢谢，
乔什
如果您想在 Startup 期间注册配置，请将此添加到 Startup.cs:
services.Configure<AppSettings>(Configuration.GetSection("App"));
然后您可以通过注入 IOptions<>:
的实例来访问它
private readonly AppSettings _appSettings;
public MyClass(IOptions<AppSettings> appSettings) {
_appSettings = appSettings.Value;
}
为了更简单的配置，我创建了一个帮助程序 class，它扫描配置对象的嵌套配置，然后尝试在加载的程序集中找到相应的 class 并使用给定的配置对其进行初始化.
appsettings.json:
{
"MyState": {
"SomeSimpleValue": "Hello World",
"MyTimeSpan": "00:15:00"
}
}
MyStateOptions.cs
// Class has same name as in appsettings.json with Options suffix.
public class MyStateOptions
{
// Properties must be deserializable from string
// or a class with a default constructor that has
// only properties that are deserializable from string.
public string SomeSimpleValue { get; set; }
public DateTime MyTimeSpan { get; set; }
}
Startup.cs
public class Startup
{
public IConfigurationRoot Configuration { get; }
public Startup(IHostingEnvironment env)
{
// Create configuration as you need it...
var builder = new ConfigurationBuilder()
.SetBasePath(env.ContentRootPath)
.AddJsonFile(...)
.AddEnvironmentVariables();
// Save configuration in property to access it later.
Configuration = builder.Build();
}
public void ConfigureServices(IServiceCollection services)
{
// Register all your desired services...
services.AddMvc(options => ...);
// Call our helper method
services.RegisterOptions(Configuration);
}
}
HelperClass.cs
public static class IServiceCollectionExtensions
{
public static void RegisterOptions(
this IServiceCollection services,
IConfiguration configuration)
{
// Create all options from the given configuration.
var options = OptionsHelper.CreateOptions(configuration);
foreach (var option in options)
{
// We get back Options<MyOptionsType> : IOptions<MyOptionsType>
var interfaces = option.GetType().GetInterfaces();
foreach (var type in interfaces)
{
// Register options IServiceCollection
services.AddSingleton(type, option);
}
}
}
}
OptionsHelper.cs
public static class OptionsHelper
{
public static IEnumerable<object> CreateOptions(IConfiguration configuration)
{
// Get all sections that are objects:
var sections = configuration.GetChildren()
.Where(section => section.GetChildren().Any());
foreach (var section in sections)
{
// Add "Options" suffix if not done.
var name = section.Key.EndsWith("Options")
? section.Key
: section.Key + "Options";
// Scan AppDomain for a matching type.
var type = FirstOrDefaultMatchingType(name);
if (type != null)
{
// Use ConfigurationBinder to create an instance with the given data.
var settings = section.Get(type);
// Encapsulate instance in "Options<T>"
var options = CreateOptionsFor(settings);
}
}
}
private static Type FirstOrDefaultMatchingType(string typeName)
{
// Find matching type that has a default constructor
return AppDomain.CurrentDomain.GetAssemblies()
.Where(assembly => !assembly.IsDynamic)
.SelectMany(assembly => assembly.GetTypes())
.Where(type => type.Name == typeName)
.Where(type => !type.IsAbstract)
.Where(type => type.GetMatchingConstructor(Type.EmptyTypes) != null)
.FirstOrDefault();
}
private static object CreateOptionsFor(object settings)
{
// Call generic method Options.Create<TOptions>(TOptions options)
var openGeneric = typeof(Options).GetMethod(nameof(Options.Create));
var method = openGeneric.MakeGenericMethod(settings.GetType());
return method.Invoke(null, new[] { settings });
}
}
完成所有这些工作后，您可以在服务集合中拥有一个服务，该服务在其构造函数中需要一个 IOptions<MyStateOptions> 并且您无需显式配置您拥有的每个选项即可获得它。只需使用所需的服务和选项实例创建一个新项目。将项目添加到您的主项目并将所需的配置添加到您的 appsettings.json.
ExampleService.cs
public class MyExampleService
{
private readonly MyStateOptions _options;
public MyExampleService(IOptions<MyStateOptions> options)
{
_options = options?.Value ?? throw new ArgumentNullException(nameof(options));
}
}
您仍然可以同时执行这两项操作。由于您在控制台应用程序中，因此可能没有使用 ASP.NET 核心元数据包，因此您需要确保具有正确的依赖项。
为了将配置绑定到对象，您需要 Microsoft.Extensions.Configuration.Binder 包。那么，这两种解决方案应该都能正常工作。
顺便说一句。即使您在控制台应用程序中，您仍然可以使用 ASP.NET Core 附带的依赖注入容器。我个人发现它的设置非常简单，所以如果你仍然可以修改你的应用程序来使用它，那可能是值得的。设置看起来像这样：
var configuration = new ConfigurationBuilder()
.AddJsonFile("config.json", optional: false)
.Build();
var services = new ServiceCollection();
services.AddOptions();
// add your services here
services.AddTransient<MyService>();
services.AddTransient<Program>();
// configure options
services.Configure<AppSettings>(configuration.GetSection("App"));
// build service provider
var serviceProvider = services.BuildServiceProvider();
// retrieve main application instance and run the program
var program = serviceProvider.GetService<Program>();
program.Run();
然后，您所有已注册的服务都可以像在 ASP.NET Core 中那样获取依赖项。为了使用您的配置，您可以像往常一样注入 IOptions<AppSettings> 类型。
直到今天我终于弄明白之前，我仍然对此有疑问。
代码 运行 没有问题，但所有属性仍然为 null，即使在绑定之后也是如此。我是这样做的：
public class AppSettings
{
public string MyProperty
}
事实证明你必须这样做：
public class AppSettings
{
public string MyProperty { get; set; }
}
它仅在您的 class 具有属性而非字段时才有效。我不清楚。
这就是我绑定设置对象并将它们添加为 .Net Core 3.0 中的单例的方式
public void ConfigureServices(IServiceCollection services)
{
var jwtSettings = new JwtSettings();
Configuration.Bind(jwtSettings);
services.AddSingleton(jwtSettings);
var databaseSettings = new DatabaseSettings();
Configuration.Bind(databaseSettings);
services.AddSingleton(databaseSettings);
services.AddControllersWithViews();
}
我的设置对象如下所示：
public class DatabaseSettings
{
public string ConnectionString { get; set; }
public string DatabaseName { get; set; }
}
public class JwtSettings
{
public string Secret { get; set; }
public string Lifetime { get; set; }
}
我的 appsettings.json 文件如下所示：
{
"DatabaseSettings": {
"ConnectionString": "mongodb://localhost:27017",
"DatabaseName": "TestDb"
},
"JwtSettings": {
"Secret": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
"Lifetime": "170"
},
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"
}
},
"AllowedHosts": "*"
}
我正在制作 .NET Core 2.0 应用程序，我需要对其进行配置。我正在查看 this documentation，似乎在 .NET Core 1.0 中你可以这样做：
var appConfig = new AppSettings();
config.GetSection("App").Bind(appConfig);
在 .NET Core 1.1 中你可以这样做：
var appConfig = config.GetSection("App").Get<AppSettings>();
但 .NET Core 2.0 中不存在 Bind 和 Get。实现这一目标的新方法是什么？
谢谢，
乔什
如果您想在 Startup 期间注册配置，请将此添加到 Startup.cs:
services.Configure<AppSettings>(Configuration.GetSection("App"));
然后您可以通过注入 IOptions<>:
private readonly AppSettings _appSettings;
public MyClass(IOptions<AppSettings> appSettings) {
_appSettings = appSettings.Value;
}
为了更简单的配置，我创建了一个帮助程序 class，它扫描配置对象的嵌套配置，然后尝试在加载的程序集中找到相应的 class 并使用给定的配置对其进行初始化.
appsettings.json:
{
"MyState": {
"SomeSimpleValue": "Hello World",
"MyTimeSpan": "00:15:00"
}
}
MyStateOptions.cs
// Class has same name as in appsettings.json with Options suffix.
public class MyStateOptions
{
// Properties must be deserializable from string
// or a class with a default constructor that has
// only properties that are deserializable from string.
public string SomeSimpleValue { get; set; }
public DateTime MyTimeSpan { get; set; }
}
Startup.cs
public class Startup
{
public IConfigurationRoot Configuration { get; }
public Startup(IHostingEnvironment env)
{
// Create configuration as you need it...
var builder = new ConfigurationBuilder()
.SetBasePath(env.ContentRootPath)
.AddJsonFile(...)
.AddEnvironmentVariables();
// Save configuration in property to access it later.
Configuration = builder.Build();
}
public void ConfigureServices(IServiceCollection services)
{
// Register all your desired services...
services.AddMvc(options => ...);
// Call our helper method
services.RegisterOptions(Configuration);
}
}
HelperClass.cs
public static class IServiceCollectionExtensions
{
public static void RegisterOptions(
this IServiceCollection services,
IConfiguration configuration)
{
// Create all options from the given configuration.
var options = OptionsHelper.CreateOptions(configuration);
foreach (var option in options)
{
// We get back Options<MyOptionsType> : IOptions<MyOptionsType>
var interfaces = option.GetType().GetInterfaces();
foreach (var type in interfaces)
{
// Register options IServiceCollection
services.AddSingleton(type, option);
}
}
}
}
OptionsHelper.cs
public static class OptionsHelper
{
public static IEnumerable<object> CreateOptions(IConfiguration configuration)
{
// Get all sections that are objects:
var sections = configuration.GetChildren()
.Where(section => section.GetChildren().Any());
foreach (var section in sections)
{
// Add "Options" suffix if not done.
var name = section.Key.EndsWith("Options")
? section.Key
: section.Key + "Options";
// Scan AppDomain for a matching type.
var type = FirstOrDefaultMatchingType(name);
if (type != null)
{
// Use ConfigurationBinder to create an instance with the given data.
var settings = section.Get(type);
// Encapsulate instance in "Options<T>"
var options = CreateOptionsFor(settings);
}
}
}
private static Type FirstOrDefaultMatchingType(string typeName)
{
// Find matching type that has a default constructor
return AppDomain.CurrentDomain.GetAssemblies()
.Where(assembly => !assembly.IsDynamic)
.SelectMany(assembly => assembly.GetTypes())
.Where(type => type.Name == typeName)
.Where(type => !type.IsAbstract)
.Where(type => type.GetMatchingConstructor(Type.EmptyTypes) != null)
.FirstOrDefault();
}
private static object CreateOptionsFor(object settings)
{
// Call generic method Options.Create<TOptions>(TOptions options)
var openGeneric = typeof(Options).GetMethod(nameof(Options.Create));
var method = openGeneric.MakeGenericMethod(settings.GetType());
return method.Invoke(null, new[] { settings });
}
}
完成所有这些工作后，您可以在服务集合中拥有一个服务，该服务在其构造函数中需要一个 IOptions<MyStateOptions> 并且您无需显式配置您拥有的每个选项即可获得它。只需使用所需的服务和选项实例创建一个新项目。将项目添加到您的主项目并将所需的配置添加到您的 appsettings.json.
ExampleService.cs
public class MyExampleService
{
private readonly MyStateOptions _options;
public MyExampleService(IOptions<MyStateOptions> options)
{
_options = options?.Value ?? throw new ArgumentNullException(nameof(options));
}
}
您仍然可以同时执行这两项操作。由于您在控制台应用程序中，因此可能没有使用 ASP.NET 核心元数据包，因此您需要确保具有正确的依赖项。
为了将配置绑定到对象，您需要 Microsoft.Extensions.Configuration.Binder 包。那么，这两种解决方案应该都能正常工作。
顺便说一句。即使您在控制台应用程序中，您仍然可以使用 ASP.NET Core 附带的依赖注入容器。我个人发现它的设置非常简单，所以如果你仍然可以修改你的应用程序来使用它，那可能是值得的。设置看起来像这样：
var configuration = new ConfigurationBuilder()
.AddJsonFile("config.json", optional: false)
.Build();
var services = new ServiceCollection();
services.AddOptions();
// add your services here
services.AddTransient<MyService>();
services.AddTransient<Program>();
// configure options
services.Configure<AppSettings>(configuration.GetSection("App"));
// build service provider
var serviceProvider = services.BuildServiceProvider();
// retrieve main application instance and run the program
var program = serviceProvider.GetService<Program>();
program.Run();
然后，您所有已注册的服务都可以像在 ASP.NET Core 中那样获取依赖项。为了使用您的配置，您可以像往常一样注入 IOptions<AppSettings> 类型。
直到今天我终于弄明白之前，我仍然对此有疑问。
代码 运行 没有问题，但所有属性仍然为 null，即使在绑定之后也是如此。我是这样做的：
public class AppSettings
{
public string MyProperty
}
事实证明你必须这样做：
public class AppSettings
{
public string MyProperty { get; set; }
}
它仅在您的 class 具有属性而非字段时才有效。我不清楚。
这就是我绑定设置对象并将它们添加为 .Net Core 3.0 中的单例的方式
public void ConfigureServices(IServiceCollection services)
{
var jwtSettings = new JwtSettings();
Configuration.Bind(jwtSettings);
services.AddSingleton(jwtSettings);
var databaseSettings = new DatabaseSettings();
Configuration.Bind(databaseSettings);
services.AddSingleton(databaseSettings);
services.AddControllersWithViews();
}
我的设置对象如下所示：
public class DatabaseSettings
{
public string ConnectionString { get; set; }
public string DatabaseName { get; set; }
}
public class JwtSettings
{
public string Secret { get; set; }
public string Lifetime { get; set; }
}
我的 appsettings.json 文件如下所示：
{
"DatabaseSettings": {
"ConnectionString": "mongodb://localhost:27017",
"DatabaseName": "TestDb"
},
"JwtSettings": {
"Secret": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
"Lifetime": "170"
},
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"
}
},
"AllowedHosts": "*"
}