Installing EF Core with Empty Template in ASP.NET MVC Core 3.0

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Threading.Tasks;

namespace MvcCoreApplication.Models
{
    public class Employee
    {
        [Key]
        public int Id { get; set; }

        [Required(ErrorMessage = "Please enter first name")]
        [Display(Name = "First Name")]
        [StringLength(100)]
        public string FirstName { get; set; }

        [Required(ErrorMessage = "Please enter last name")]
        [Display(Name = "Last Name")]
        [StringLength(100)]
        public string LastName { get; set; }

        [Required(ErrorMessage = "Please choose gender")]
        [StringLength(10)]
        public string Gender { get; set; }

        [Required(ErrorMessage = "Please enter age")]
        public int Age { get; set; }

        [Required(ErrorMessage = "Please enter position")]
        [StringLength(100)]
        public string Position { get; set; }

        [Required(ErrorMessage = "Please enter office")]
        [StringLength(100)]
        public string Office { get; set; }

        [Required(ErrorMessage = "Please enter first name")]
        public int Salary { get; set; }
    }
}

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

namespace MvcCoreApplication.Models
{
    public class EmployeeDbContext : DbContext
    {
        public EmployeeDbContext(DbContextOptions options)
            : base(options)
        {

        }

        public DbSet<Employee> Employees { get; set; }
    }
}

Step 4. Now open the appsettings.json file and add connect how we use set the connection in web config file. Similarly here you need to setup connect string.

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "DefaultConnection": "server=(localdb)\\MSSQLLocalDB;database=DemoDB;Trusted_Connection=true"
  }
}

Step 5. Visual Studio 2019 generates program and startup classes. Now open the startup file and configure ASP.Net MVC Core Application development. Under app.UseEndpoints method just map endpoints.MapControllerRoute. Add connection middleware in services.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using MvcCoreApplication.Models;

namespace MvcCoreApplication
{
    public class Startup
    {
        private readonly IConfiguration Configuration;

        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public void ConfigureServices(IServiceCollection services)
        {
            // Add MVC Middleware
            services.AddControllersWithViews();

            // Add Connection Middleware
            services.AddDbContext<EmployeeDbContext>(
                options => options.UseSqlServer(this.Configuration.GetConnectionString("DefaultConnection")));
        }

        // 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.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                // Add MVC Default route
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}"
                    );
            });
        }
    }
}

Step 6. Now go to tools select nuget package manage than click on package manager console. It will bring console window below in visual studio 2019. Now write the following commands to enable migration.

• enable-migrations
• add-migration InitialModel (add migration can be anything you wish to)
• update-database
  
  
  

Here is the complete code.