InvalidOperationException：没有为此 DbContext 配置数据库提供程序。

Question

使用 entityframeworkcore 2.03 .net core 构建一个 web api

不断收到以下错误尝试了我能想到的一切以克服它不确定是什么问题有没有其他人有这个问题？

InvalidOperationException：未配置数据库提供程序 对于这个 DbContext。可以通过覆盖来配置提供程序 DbContext.OnConfiguring 方法或通过使用 AddDbContext 上 应用服务提供商。如果使用了 AddDbContext，那么也 确保您的 DbContext 类型接受 DbContextOptions 构造函数中的对象并将其传递给基构造函数 数据库上下文

startup.cs

using churchy.Repository;
    using churchy.Service;
    using churchy.Service.Abstractions;
    using Microsoft.AspNetCore.Builder;
    using Microsoft.AspNetCore.Hosting;
    using Microsoft.EntityFrameworkCore;
    using Microsoft.Extensions.Configuration;
    using Microsoft.Extensions.DependencyInjection;

namespace churchy
{
    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)
        {

            // Database connection
            services.AddDbContext<ChurchContext>(options =>
        options.UseSqlServer(Configuration.GetConnectionString("ChurchConnection")));

            // Repositories
            services.AddScoped<IRepository, Repository.Repository>();
            services.AddScoped<IRepositoryFactory, RepositoryFactory>();

            // Services
            services.AddScoped<IChurchService, ChurchService>();

            services.AddMvc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseMvc();
        }
    }
}

churchcontext.cs

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.EntityFrameworkCore;
using churchy.Model;


namespace churchy.Repository
{
    public class ChurchContext: DbContext
    {
        public ChurchContext()
        {
        }

        public ChurchContext(DbContextOptions<ChurchContext> options) : base(options)
        {
        }


        public DbSet<Church> Churches { get; set; }
        public DbSet<Location> Locations { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Church>().ToTable("Church");
        }
    }
}

Repository.cs

using Microsoft.EntityFrameworkCore;
using System.Linq;
using System.Threading.Tasks;

namespace churchy.Repository
{
    public class Repository : IRepository
    {
        private readonly ChurchContext _context;

        public Repository()
        {
            _context = new ChurchContext();
        }

        public IQueryable<T> GetAll<T>() where T : class
        {
            return  _context.Set<T>();
        }

        public Task Create<T>(T entity) where T : class
        {
            throw new System.NotImplementedException();
        }

        public Task Delete<T>(int id) where T : class
        {
            throw new System.NotImplementedException();
        }

        public Task Update<T>(int id, T entity) where T : class
        {
            throw new System.NotImplementedException();
        }

        public void Dispose()
        {
            _context?.Dispose();
        }
    }
}

IRepository.cs

using System;
using System.Linq;
using System.Threading.Tasks;

namespace churchy.Repository
{
    public interface IRepository : IDisposable
    {
        IQueryable<T> GetAll<T>() where T : class;
        Task Create<T>(T entity) where T :class;
        Task Update<T>(int id, T entity) where T : class;
        Task Delete<T>(int id) where T : class;
    }
}

ChurchController

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using churchy.Service.Abstractions;

namespace churchy.Controllers
{
    [Route("api/church")]
    public class ChurchController : Controller
    {
        private readonly IChurchService _churchService;
        public ChurchController(IChurchService churchService)
        {
            _churchService = churchService;
        }
        // GET: api/<controller>
        [HttpGet]
        public IActionResult GetAllAsync()
        {
            var response = _churchService.getChurches();

            return Ok(response);
        }

        // GET api/<controller>/5
        [HttpGet("{id}")]
        public string Get(int id)
        {
            return "value3";
        }

        // POST api/<controller>
        [HttpPost]
        public void Post([FromBody]string value)
        {
        }

        // PUT api/<controller>/5
        [HttpPut("{id}")]
        public void Put(int id, [FromBody]string value)
        {
        }

        // DELETE api/<controller>/5
        [HttpDelete("{id}")]
        public void Delete(int id)
        {
        }
    }
}

Answer 1

这是你最基本的问题：

public Repository()
{
    _context = new ChurchContext();
}

这与依赖注入相反。您手动创建的上下文未配置。

快速回答：

public Repository(ChurchContext context)
{
    _context = context;
}

此外：

• 您应该熟悉 ASP.NET Core 中的依赖注入：Dependency Injection in ASP.NET Core。
• 您可能需要阅读this answer of mine，了解有关 ASP.NET Core 中的 UoW 和存储库模式的一些观点。