SampleDataSeeder.cs

using Microsoft.EntityFrameworkCore;
using System.Threading;
using System.Threading.Tasks;
using MySample.Entities;
using SSW.DataOnion.Interfaces;

namespace MySample.Data.SampleData
{
    public class SampleDataSeeder : IDataSeeder
    {
        public void Seed<TDbContext>(TDbContext dbContext) where TDbContext : DbContext
        {
            this.PopulateData(dbContext);

            dbContext.SaveChanges();
        }

        public async Task SeedAsync<TDbContext>(TDbContext dbContext, CancellationToken cancellationToken = new CancellationToken()) where TDbContext : DbContext
        {
            this.PopulateData(dbContext);
            await dbContext.SaveChangesAsync(cancellationToken);
        }

        private void PopulateData<TDbContext>(TDbContext dbContext) where TDbContext : DbContext
        {
            var category1 = new ProductCategory {Name = "TVs"};
            var category2 = new ProductCategory { Name = "Microwaves" };
            var category3 = new ProductCategory { Name = "Fridges" };

            var product1 = new Product { Category = category1, Name = "42 inch Plazma TV", Sku = "42P" };
            var product2 = new Product { Category = category1, Name = "55 inch LED TV", Sku = "55LED" };
            var product3 = new Product { Category = category3, Name = "Small bar fridge", Sku = "SBF" };
            var product4 = new Product { Category = category3, Name = "Medium Fridge", Sku = "MF" };
            var product5 = new Product { Category = category3, Name = "Large French Door Fridge", Sku = "FDF" };

            dbContext.Set<ProductCategory>().AddOrUpdate(category1);
            dbContext.Set<ProductCategory>().AddOrUpdate(category2);
            dbContext.Set<ProductCategory>().AddOrUpdate(category3);

            dbContext.Set<Product>().AddOrUpdate(product1);
            dbContext.Set<Product>().AddOrUpdate(product2);
            dbContext.Set<Product>().AddOrUpdate(product3);
            dbContext.Set<Product>().AddOrUpdate(product4);
            dbContext.Set<Product>().AddOrUpdate(product5);

        }
    }
}