An code base changes when we switch from text file as a storage to a database. Context classes are out of scope as they are not important

2.js

using System.Diagnostics;
using Akka.Actor;
using Akka.Cluster.Hosting;
using Akka.Event;
using Akka.Hosting;
using Akka.Routing;
using Akka.Remote.Hosting;
using ASimpleApiwithActor;
using Microsoft.EntityFrameworkCore;

var environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ?? "Development";

var builder = WebApplication.CreateBuilder(args);
builder.Configuration
    .AddJsonFile("appsettings.json")
    .AddJsonFile($"appsettings.{environment}.json", optional: true)
    .AddEnvironmentVariables();

builder.Logging.ClearProviders().AddConsole();
builder.Services.AddControllers();

var app = builder.Build();
app.UseRouting();

var system = ActorSystem.Create("example");
var bookActor = system.ActorOf(Props.Create(() => new BookActor()), "book");

app.UseEndpoints(endpoints => {
    endpoints.MapControllers();
    endpoints.MapPost("/actor", async(HttpContext context, BookData bd) =>
        {
            var bookId = await bookActor.Ask < ulong > (bd);
            await context.Response.WriteAsync(bookId.ToString());
        });

    endpoints.MapPost("/class", async(HttpContext context, BookData bd) =>
        {
            //this is normally injected as DI in the constructory
            var bookWriterForClass = new BookWriter();
            var bookId = bookWriterForClass.WriteBook(bd);
            await context.Response.WriteAsync(bookId.ToString());
        });
});

await app.RunAsync();

public class BookWriter {
    private FirstoneContext _ctx;
    public ulong WriteBook(BookData bd) {
        _ctx = new FirstoneContext();
        var book = new Book
        {
            AuthorName = bd.AuthorName,
                Title = bd.Title
        };

        _ctx.Add(book);
        _ctx.SaveChanges();

        return book.Id;
    }
}

public sealed class BookActor : ReceiveActor
{
    private readonly ILoggingAdapter _log = Context.GetLogger();
    private BookWriter _bookWriter = new BookWriter();

    public BookActor()
    {
        Receive < BookData > (_ => {
            var id = _bookWriter.WriteBook(_);
            Sender.Tell(id);
        });
    }
}

public class BookData {
    public long Id { get; set; }
    public string Title { get; set; } = string.Empty;
    public string AuthorName { get; set; } = string.Empty;
}