efcore数据库自动生成

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.ConfigureNLog("nlog.config");
            loggerFactory.AddNLog();

            app.UseRequestIPMiddleware();

            InitializeNetCoreBBSDatabase(app.ApplicationServices);
            app.UseDeveloperExceptionPage();

            app.UseStaticFiles();
            app.UseAuthentication();
            app.UseStatusCodePages();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "areaRoute",
                    template: "{area:exists}/{controller}/{action}",
                    defaults: new { action = "Index" });
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }

        private void InitializeNetCoreBBSDatabase(IServiceProvider serviceProvider)
        {
            using (var serviceScope = serviceProvider.GetRequiredService<IServiceScopeFactory>().CreateScope())
            {
                var db = serviceScope.ServiceProvider.GetService<DataContext>();
                db.Database.Migrate();
                if (db.TopicNodes.Count() == )
                {
                    db.TopicNodes.AddRange(GetTopicNodes());
                    db.SaveChanges();
                }
            }
        }