我有一个基于 ASP.NET Core 3.1 的应用程序。在应用程序启动期间,在ConfigureServices(IServiceCollection services)
我想注册我的服务。但在配置服务期间,我想根据数据库中找到的设置启动应用程序。
这是我的代码
public void ConfigureServices(IServiceCollection services)
{
// Register context
services.AddDbContext<AppDbContext>(options =>
{
options.UseMySql(Configuration.GetConnectionString("MySqlServerConnection"));
});
// Reister the setting provider
services.AddSingleton<IAppSetting, AppSettings>();
// Create a resolver which is WRONG!!
var resolver = services.BuildServiceProvider();
var setting = resolver.GetService<IAppSetting>();
List<string> allowedCors = new List<string>()
{
setting.MainUrl.ToString()
};
if (setting.HasCustomAssetsUri)
{
allowedCors.Add(settings.AssetsUrl.ToString());
}
if (settings.HasCustomPhotosUri)
{
allowedCors.Add(settings.PhotosUrl.ToString());
}
services.AddCors(options =>
{
options.AddPolicy("AllowSubDomainTraffic",
builder =>
{
builder.WithOrigins(allowedCors.ToArray())
.AllowAnyHeader()
.AllowAnyMethod();
});
});
// More services
}
正如您在上面的代码中看到的,我注册了IAppSetting
但我立即想用来访问数据库,以便获取当前配置。我目前正在打电话services.BuildServiceProvider()
创建一个新的解析器,然后我可以使用它来创建一个实例IAppSetting
.
My AppSetting
实施取决于AppDbContext
这也已注册。这是我的应用程序设置
public class AppSetting : IAppSetting
{
private AppDbContext context;
public AppSetting(AppDbContext context)
{
this.context = context;
}
// methods...
}
Calling BuildServiceProvider()
将导致创建单例服务的附加副本。所以我试图避免这样做。
如何正确注册然后解决IAppSetting
in the ConfigureServices()
方法,以便我可以使用它来访问数据库中找到的设置?
Updated
我尝试使用 Nkosi 提出的解决方案,但出现以下错误
System.InvalidOperationException:“无法解析范围服务
来自根提供商的“IAppSetting”。
这是完整的堆栈跟踪。
This exception was originally thrown at this call stack:
Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteValidator.ValidateResolution(System.Type, Microsoft.Extensions.DependencyInjection.IServiceScope, Microsoft.Extensions.DependencyInjection.IServiceScope)
Microsoft.Extensions.DependencyInjection.ServiceProvider.Microsoft.Extensions.DependencyInjection.ServiceLookup.IServiceProviderEngineCallback.OnResolve(System.Type, Microsoft.Extensions.DependencyInjection.IServiceScope)
Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(System.Type, Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope)
Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(System.Type)
Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(System.IServiceProvider, System.Type)
Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(Microsoft.Extensions.DependencyInjection.ServiceLookup.FactoryCallSite, Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext)
Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitDisposeCache(Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceCallSite, Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext)
...
[Call Stack Truncated]