Programmatically Seeding Large Amounts of Data using EFCore 7.0

DbSeeder.cs

using System.Reflection;
using Blog.Models;
using Newtonsoft.Json;

namespace Blog.Data;

public class DbSeeder
{
    private readonly PostContext _postContext;  

    public DbSeeder(PostContext postContext)
    {
        _postContext = postContext;
    }
    
    public void SeedData()
    {
        _postContext.Database.EnsureCreated();
        var hasData = _postContext.Post.FirstOrDefault();

        if (hasData == null)
        {
            var posts = new List<Post>();
            Assembly asm = Assembly.GetExecutingAssembly();
            var allFileNames = asm.GetManifestResourceNames();

            using (Stream resStream = asm.GetManifestResourceStream(allFileNames[0]))
            {
                if (resStream == null)
                {
                    Console.WriteLine($"\nResource was found to be null!\n");
                    return;
                }

                using (StreamReader r = new StreamReader(resStream))
                {
                    string json = r.ReadToEnd();
                    posts = JsonConvert.DeserializeObject<List<Post>>(json);
                }
            }

            foreach (var post in posts)
            {
                _postContext.Post.Add(post);
            }

            _postContext.SaveChanges();

            Console.WriteLine($"Seeded {posts.Count} posts to the database.");
        }
    }
}

Post.cs

/*
 * This class is a model class containing properties to describe a blog post.
 * The properties defined in this class map to an array of JSON objects describing
 * thousands of blog posts.
 *
 * In the JSON file I am using, some post id's are null, and so a post's title
 * has been used as a key instead. 
 */

using System.ComponentModel.DataAnnotations;

namespace Blog.Models;

public class Post
{
    public int? Id { get; set; }
    [Key]
    public string Title { get; set; }
    public string Content { get; set; }
    public string Url { get; set; }
}

PostContext.cs

using Microsoft.EntityFrameworkCore;

public class PostContext : DbContext
    {
        public PostContext (DbContextOptions<PostContext> options)
            : base(options)
        {
        }

        public DbSet<Blog.Models.Post> Post { get; set; } = default!;
        
    }

Program.cs

using Blog.Data;
using Microsoft.EntityFrameworkCore;
var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddRazorPages();
builder.Services.AddDbContext<PostContext>(options =>
    options.UseSqlite(builder.Configuration.GetConnectionString("PostContext") ?? throw new InvalidOperationException("Connection string 'PostContext' not found.")));

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.MapRazorPages();

using (var scope = app.Services.CreateScope())
{
    var serviceProvider = scope.ServiceProvider;
    var postContext = serviceProvider.GetRequiredService<PostContext>();
    var dbSeeder = new DbSeeder(postContext);
    dbSeeder.SeedData();
}

app.Run();