ASP.NET 核心 Web API InvalidOperationException：无法解析服务

Question

我正在尝试构建一个简单的 api 作为对项目未来 api 的测试。但是我一直有这个错误

InvalidOperationException: Unable to resolve service for type 'AspnetCore_WebApi.Models.TarefaContext' while attempting to activate 'AspnetCore_WebApi.Models.TarefaRepositorio'.

这里是TarefaContext.cs

using Microsoft.EntityFrameworkCore;
namespace AspnetCore_WebApi.Models
{
    public class TarefaContext : DbContext
    {
        public TarefaContext(DbContextOptions<TarefaContext> options)
            : base(options)
        { }
        public DbSet<TarefaItem> TarefaItens { get; set; }
    }
}

TarefaRepositorio.cs

using System.Collections.Generic;
using System.Linq;
namespace AspnetCore_WebApi.Models
{
    public class TarefaRepositorio : ITarefaRepositorio
    {
        private readonly TarefaContext _context;
        public TarefaRepositorio(TarefaContext context)
        {
            _context = context;
            Add(new TarefaItem { Nome = "Item1" });
        }
        public IEnumerable<TarefaItem> GetAll()
        {
            return _context.TarefaItens.ToList();
        }
        public void Add(TarefaItem item)
        {
            _context.TarefaItens.Add(item);
            _context.SaveChanges();
        }
        public TarefaItem Find(long key)
        {
            return _context.TarefaItens.FirstOrDefault(t => t.Chave == key);
        }
        public void Remove(long key)
        {
            var entity = _context.TarefaItens.First(t => t.Chave == key);
            _context.TarefaItens.Remove(entity);
            _context.SaveChanges();
        }
        public void Update(TarefaItem item)
        {
            _context.TarefaItens.Update(item);
            _context.SaveChanges();
        }
    }
}

TarefaController.cs

using System.Collections.Generic;
using AspnetCore_WebApi.Models;
using Microsoft.AspNetCore.Mvc;
namespace AspnetCore_WebApi.Controllers
{
    [Route("api/[controller]")]
    public class TarefaController : Controller
    {
        private readonly ITarefaRepositorio _tarefaRepositorio;
        public TarefaController(ITarefaRepositorio tarefaRepositorio)
        {
            _tarefaRepositorio = tarefaRepositorio;
        }
        [HttpGet]
        public IEnumerable<TarefaItem> GetAll()
        {
            return _tarefaRepositorio.GetAll();
        }

        [HttpGet("{id}", Name = "GetTarefa")]
        public IActionResult GetById(long id)
        {
            var item = _tarefaRepositorio.Find(id);
            if (item == null)
            {
                return NotFound();
            }
            return new ObjectResult(item);
        }

        [HttpPost]
        public IActionResult Create([FromBody] TarefaItem item)
        {
            if (item == null)
            {
                return BadRequest();
            }
            _tarefaRepositorio.Add(item);
            return CreatedAtRoute("GetTarefa", new { id = item.Chave }, item);
        }
    }
}

我TarefaRepositorio.cs

using System.Collections.Generic;
namespace AspnetCore_WebApi.Models
{
    public interface ITarefaRepositorio
    {
        void Add(TarefaItem item);
        IEnumerable<TarefaItem> GetAll();
        TarefaItem Find(long key);
        void Remove(long key);
        void Update(TarefaItem item);
    }
}

Answer 1

错误消息描述依赖注入无法解析您的 TarefaContext class。您应该使用 services.AddDbContext 方法在启动 ConfigureServices 方法中注册您的数据库上下文。有关详细信息，请参阅 Microsoft 文档：https://docs.microsoft.com/en-us/ef/core/miscellaneous/configuring-dbcontext

Answer 2

As Scott and Artis said in I haven't added my Context Class to the startup.cs file. I had some trouble with the article mentioned by Artis 因为我使用的是 EF Core InMemory 所以我不得不添加

services.AddDbContext<TarefaContext>(options => options.UseInMemoryDatabase());

改为 Startup.cs 的 ConfigureServices

services.AddDbContext<TarefaContext>(options => options.UseSqlite("Data Source=someDB.db"));

谢谢大家的帮助

ASP.NET 核心 Web API InvalidOperationException：无法解析服务

ASP.NET Core Web API InvalidOperationException: Unable to resolve service

c#

asp.net-mvc

asp-net-core-spa-services