I am trying to get started with some onion architecture with some Code First Entity Framework for .NET Core.

Following this, I made this stuff today:

1. using Microsoft.EntityFrameworkCore;
   using FluffyNothing.Core.Objects;
   namespace FluffyNothing.Infrastructure.ExternalDependencies.Repositories
   {
      public class PlayerContext : DbContext
      {
         public PlayerContext(DbContextOptions options) : base(options)
         {
            
         }
         
         protected override void OnConfiguring(DbContextOptionsBuilder dbCob)
         {
            dbCob.UseSqlServer(ConnectionString.Use());
         }
         
         public DbSet<Player> Players { get; set; }
      }
   }
    
2. using System.ComponentModel.DataAnnotations.Schema;
   namespace FluffyNothing.Core.Objects
   {
      public class Player
      {
         [Key]
         [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
         public long PlayerId { get; set; }
         public string PlayerIp { get; set; }
      }
   }
    
3. using Microsoft.EntityFrameworkCore;
   using FluffyNothing.Core.Interfaces.Repositories;
   using FluffyNothing.Core.Objects;
   namespace FluffyNothing.Infrastructure.ExternalDependencies.Repositories
   {
      public class PlayerRepository : IPlayerRepository
      {
         public void AddPlayer(Player player)
         {
            var optionsBuilder = new DbContextOptionsBuilder<PlayerContext>();
            using (var context = new PlayerContext(optionsBuilder.Options))
            {
               //coming soon
            }
         }
      }
   }

 
 

At the NuGet console in Visual Studio 2019 I changed the "Default project:" to the infrastructure project and then I ran these two commands to make the database:

1. Add-Migration EFCoreCodeFirstSample.Models.PaymentContext
2. update-database

 
 

This sets up the database and storage for the migrations in a table at the database and a folder in the infrastructure project! When you cannot use .UseSqlServer with Microsoft.EntityFrameworkCore try this command:

Install-Package Microsoft.EntityFrameworkCore.SqlServer YourProjectNameHere

 
 

Addendum 7/20/2019: Add-Migration EFCoreCodeFirstSample.Models.PaymentContext above should really be Add-Migration EFCoreCodeFirstSample.Models.PlayerContext to tell the truth, you know? Another thing I should mention is that I had to have services.AddDbContext<PlayerContext>(); just inside ConfigureServices method in Startup.cs back in the UI project. Otherwise, the command I just mentioned won't run.