ASP.NET MVC项目添加Identity后运行出现依赖注入错误

错误信息：构造服务描述符时出错（验证服务描述符 'ServiceType: CandySoap.DataAccess.Repository.IRepository.IUnitOfWork Lifetime: Scoped ImplementationType: CandySoap.DataAccess.Repository.UnitOfWork' 失败：无法解析依赖项）

问题原因 #

依赖注入容器无法解析UnitOfWork初始化时用到的仓储接口（ICategoryRepository、ICovertypesRepository、IProductRepository），因为这些接口未注册到服务容器中。

解决方案 #

在Program.cs的服务注册环节，新增所有仓储接口与实现类的依赖注入配置：

// 注册仓储接口及其实现
builder.Services.AddScoped<ICategoryRepository, CategoryRepository>();
builder.Services.AddScoped<ICovertypesRepository, CovertypesRepository>();
builder.Services.AddScoped<IProductRepository, ProductRepository>();

同时检查以下两点：

• 确保所有仓储类已正确实现对应接口
• ApplicationContext的继承与连接字符串配置无问题

相关代码参考 #

Program.cs 代码

using CandySoap.Data;
using CandySoap.DataAccess.Repository;
using CandySoap.DataAccess.Repository.IRepository;
using Microsoft.EntityFrameworkCore;
using Microsoft.AspNetCore.Identity;

var builder = WebApplication.CreateBuilder(args);

// 向容器添加服务
builder.Services.AddControllersWithViews();
builder.Services.AddDbContext<ApplicationContext>(option => option.UseSqlServer(builder.Configuration.GetConnectionString("ConnectionLink")));

builder.Services.AddDefaultIdentity<IdentityUser>()
    .AddEntityFrameworkStores<ApplicationContext>();

// 新增：注册所有仓储接口
builder.Services.AddScoped<ICategoryRepository, CategoryRepository>();
builder.Services.AddScoped<ICovertypesRepository, CovertypesRepository>();
builder.Services.AddScoped<IProductRepository, ProductRepository>();
builder.Services.AddScoped<IUnitOfWork, UnitOfWork>();

var app = builder.Build();

// 配置HTTP请求管道
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Home/Error");
    // 默认HSTS值为30天，生产环境可根据需要修改
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();
app.UseAuthentication();

app.UseAuthorization();

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

app.Run();

// 注：此处using语句位置错误，应移至文件顶部
// using Microsoft.AspNetCore.Identity.EntityFrameworkCore;

ApplicationContext 类代码

using Microsoft.EntityFrameworkCore;

namespace CandySoap.Data
{
    public class ApplicationContext : IdentityDbContext
    {
        public ApplicationContext(DbContextOptions<ApplicationContext> option) : base(option) { }
        public DbSet<Category> categories { get; set; }
        public DbSet<Covertype> covertypes { get; set; }
        public DbSet<Product> products { get; set; }
    }
}

UnitOfWork 类代码

using CandySoap.Data;
using CandySoap.DataAccess.Repository.IRepository;

namespace CandySoap.DataAccess.Repository
{
    public class UnitOfWork : IUnitOfWork
    {
        private ApplicationContext _db;

        public UnitOfWork(ApplicationContext db)
        {
            _db = db;
            Category = new CategoryRepository(_db);
            Covers = new CovertypesRepository(_db);
            Product = new ProductRepository(_db);
        }
        public ICategoryRepository Category { get; private set; }

        public ICovertypesRepository Covers { get; private set; }

        public IProductRepository Product { get; private set; }

        public void Save()
        {
            _db.SaveChanges();
        }
    }
}

内容的提问来源于stack exchange，提问作者baba