DBcontext 类在单独的类库和Asp.net core webapi 应用是一个单独的项目

如何解决DBcontext 类在单独的类库和Asp.net core webapi 应用是一个单独的项目

包管理器控制台图像 1

1. 我将开始项目作为 Sample.API 和默认项目作为 DataRepository\SampleApplicationDatabase。我正在尝试添加通过给出这样的命令进行迁移：Add-Migration addtable -Context SampleApplicationContext"
  
  它抛出如下错误“无法创建'SampleApplicationContext'类型的对象。添加一个实现 'IDesignTimeDbContextFactory' 到项目，或查看 https://go.microsoft.com/fwlink/?linkid=851728 额外设计时支持的模式。 mypackagemanagerconsole"
  
  我不明白我犯了什么错误，谁能帮我解决这个问题，谢谢。

Sample.Api 应用设置

{
  "SampleApplicationConnectionstring": {
    "ConnectionString": "Server=TEKFRIDAY281;Database=SampleApplication;User ID=sa;Password=friday123!;Trusted_Connection=True;MultipleActiveResultSets=true;Integrated Security=false"
    
      },"Logging": {
        "LogLevel": {
          "Default": "information","Microsoft": "Warning","Microsoft.Hosting.Lifetime": "information"
        }
      },"AllowedHosts": "*"
    }

Sample.Api 的启动

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using API_Interface;
using DataAccessLayer;
using IRepository;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Repository;
using SampleApplicationDatabase;

namespace Sample.API
{
    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.AddTransient<IData,Data>();
            services.AddTransient<IUnitOfWork,UnitOfWork>();
            services.AddControllers();
            services.AddMvc();
            services.AddDbContext<SampleApplicationContext>(options => options.UsesqlServer(Configuration.GetConnectionString("ConnectionString")));
          
        }

        // 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.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

DataRepository 中的 SampleApplicationContext.cs 文件

using Microsoft.EntityFrameworkCore;
using SampleApplicationModels;
using System;
using System.Linq;

namespace SampleApplicationDatabase
{
    public class SampleApplicationContext:DbContext
    {
        public SampleApplicationContext(DbContextOptions<SampleApplicationContext> options) : base(options)
        {

        }

        public DbSet<AdminCredentials> AdminCredentials { get; set; }
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            foreach (var relationship in modelBuilder.Model.GetEntityTypes().SelectMany(e => e.GetForeignKeys()))
            {
                relationship.DeleteBehavior = DeleteBehavior.Restrict;
            }

            base.OnModelCreating(modelBuilder);
        }
    }
}