部分服务无法构建

Question

我有一个 ASP.NET Core 3.1 MVC 解决方案，我在其中创建了一个 class 用于收集解决方案中常用的函数。

我已经在 startup.cs 中注册了 class，如下所示：

services.AddSingleton<ITeamFunctions, TeamFunctions>();

class 的接口 (ITeamFunctions) 如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace PI.Interfaces
{
    public interface ITeamFunctions
    {
        Task UpdateTeamStat(int teamId);
        Task<float> CalculatePriceToPay();
    }
}

而 class 本身是这样的：

using System.Linq;
using System.Security.Claims;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using System.Transactions;

namespace PI.Utility
{
    public class TeamFunctions : ITeamFunctions
    {
        private readonly ApplicationDbContext _db;
        private readonly UserManager<IdentityUser> _userManager;
        private readonly IHttpContextAccessor _httpContextAccessor;

        public TeamFunctions(ApplicationDbContext db, UserManager<IdentityUser> userManager, IHttpContextAccessor httpContextAccessor)
        {
            _db = db;
            _userManager = userManager;
            _httpContextAccessor = httpContextAccessor;
        }

        Task UpdateTeamStat(int teamId)
        {
        //code here
        }

        Task<float> CalculatePriceToPay();
        {
        //code here
        }

当运行解决方案时，它给我这个错误：

System.AggregateException: 'Some services are not able to be constructed (Error while validating the service descriptor 'ServiceType: PI.Interfaces.ITeamFunctions Lifetime: Singleton ImplementationType: PI.Utility.TeamFunctions': Unable to resolve service for type 'Microsoft.AspNetCore.Identity.UserManager`1[Microsoft.AspNetCore.Identity.IdentityUser]' while attempting to activate 'PI.Utility.TeamFunctions'.)'

在 TeamFunction 中禁用 IdentityUser 注入，它抱怨我的 ApplicationDbContext。我已经在 startup.cs 中尝试了范围（用 AddScoped 更改 AddSingleton）但没有任何区别。我在 Core 2.2 解决方案中有一个类似的架构。

想知道我错过了什么吗？

编辑：完整的 startup.cs 如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.UI;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.EntityFrameworkCore;
using PI.Data;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using PI.Models;
using Microsoft.AspNetCore.Http;
using PI.Utility;
using PI.Interfaces;
using Microsoft.AspNetCore.Identity.UI.Services;
using PI.Service;
using PI.Installers;

namespace PI
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<ApplicationDbContext>(options =>
                options.UseSqlServer(
                    Configuration.GetConnectionString("DefaultConnection")));

            services.AddDefaultIdentity<ApplicationUser>()
                .AddRoles<IdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext>();

            services.Configure<IdentityOptions>(options =>                  
            {
                // Default Password settings.
                options.Password.RequireDigit = false;
                options.Password.RequireLowercase = true;
                options.Password.RequireNonAlphanumeric = false;
                options.Password.RequireUppercase = false;
                options.Password.RequiredLength = 6;
                options.Password.RequiredUniqueChars = 0;
            });

            services.Configure<CookiePolicyOptions>(options =>
            {
                options.CheckConsentNeeded = context => false;
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });

            services.AddSession(options =>                                  
            {
                options.Cookie.IsEssential = true;
                options.IdleTimeout = TimeSpan.FromMinutes(60);
                options.Cookie.HttpOnly = true;
            });

            services.AddSingleton<IEmailSender, EmailSender>();
            services.Configure<EmailOptions>(Configuration);
            services.AddSingleton<ITeamFunctions, TeamFunctions>();
            services.AddControllersWithViews();
            services.AddRazorPages().AddRazorRuntimeCompilation();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseDatabaseErrorPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();
            app.UseSession();                                              

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapAreaControllerRoute(
                    name: "admin",
                    areaName: "admin",
                    pattern: "Admin/{controller=User}/{action=Index}/{id?}"
                    );

                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{area=Main}/{controller=Home}/{action=Index}/{id?}");
                endpoints.MapRazorPages();
            });

            app.UseCookiePolicy(); 
        }
    }
}

Answer 1

如图所示ConfigureServices

services.AddDefaultIdentity<ApplicationUser>()
//...

内部注册了UserManager<ApplicationUser>，但是要解析的class(TeamFunctions)的构造函数依赖于UserManager<IdentityUser>。

因此，容器不知道如何根据启动时显示的配置服务处理该依赖关系，并抛出所述异常。

更新构造函数以明确期望配置的类型。

//ctor
public TeamFunctions(
    ApplicationDbContext db, 
    UserManager<ApplicationUser> userManager, //<-- note the type used.
    IHttpContextAccessor httpContextAccessor) {

    //...omitted for brevity

}

其次，UserManager添加了范围服务生命周期

//...

services.TryAddScoped<UserManager<TUser>>();

//...

Source code

并且由于 Scoped 生命周期不能很好地与 Singleton 配合使用，因此该服务也应该添加为 scoped。

//...

services.AddScoped<ITeamFunctions, TeamFunctions>();

//...

部分服务无法构建

Some services are not able to be constructed

c#

dependency-injection

asp.net-core-mvc

asp.net-core-3.1