Optymistyczna współbieżność w EF Core

DataContext.cs

public class DataContext : DbContext
{
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer(@"Server=.\SQLEXPRESS;Database=EFCoreOptimisticConcurrency;Trusted_Connection=True;");
    }

    public DbSet<Product> Products { get; set; }
}

DataContext2.cs

public class DataContext : DbContext
{
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer(@"Server=.\SQLEXPRESS;Database=EFCoreOptimisticConcurrency;Trusted_Connection=True;");
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());
    }

    public DbSet<Product> Products { get; set; }
}

EditProduct.cs

private static async Task EditProduct(Guid productId, Action<Product> editAction, int delay)
{
    await using var db = new DataContext();

    var product = await db.Products.FirstOrDefaultAsync(p => p.Id == productId);

    await Task.Delay(delay);

    editAction(product);

    await db.SaveChangesAsync();
}

EditProduct2.cs

private static async Task EditProduct(Guid productId, Action<Product> editAction, int delay)
{
    await using var db = new DataContext();

    try
    {
        var product = await db.Products.FirstOrDefaultAsync(p => p.Id == productId);

        await Task.Delay(delay);

        editAction(product);

        await db.SaveChangesAsync();
    }
    catch (DbUpdateConcurrencyException ex)
    {
        foreach (var entry in ex.Entries)
        {
            var databaseValues = await entry.GetDatabaseValuesAsync();

            foreach (var property in entry.CurrentValues.Properties)
            {
                var proposedValue = entry.CurrentValues[property];
                var databaseValue = databaseValues[property];
                var originalValue = entry.OriginalValues[property];

                if (proposedValue.Equals(databaseValue) || originalValue.Equals(databaseValue) || property.Name == "RowVersion")
                {
                    continue;
                }

                Console.WriteLine($"ProposedValue: {proposedValue}, DatabaseValue: {databaseValue}, OriginalValue: {originalValue}.");

                //proposedValues[property] = wartość do zapisu;
            }

            entry.OriginalValues.SetValues(databaseValues);
        }
    }
}

Main.cs

static async Task Main(string[] args)
{
    var productId = Guid.Parse("E440B325-AD1F-4B4D-9162-36DFB0F3A357");

    await Setup(productId);

    var tasks = new[]
    {
        EditProduct(productId, p => p.Price = 11, 1000),
        EditProduct(productId, p => p.Price = 12, 100)
    };

    await Task.WhenAll(tasks);

    var product = await GetProduct(productId);

    Console.WriteLine($"Product: {product.Name}, price: {product.Price}");
}

Main2.cs

EditProduct(productId, p => p.Price = 11, 1000),
EditProduct(productId, p => p.Name = "new product", 100)

Product.cs

public class Product
{
    public Guid Id { get; set; } = Guid.NewGuid();

    public string Name { get; set; }

    public decimal Price { get; set; }
}

Product2.cs

public class Product
{
    public Guid Id { get; set; } = Guid.NewGuid();

    public string Name { get; set; }

    public decimal Price { get; set; }

    public byte[] RowVersion { get; set; }
}

ProductEntityTypeConfiguration.cs

public class ProductEntityTypeConfiguration : IEntityTypeConfiguration<Product>
{
    public void Configure(EntityTypeBuilder<Product> builder)
    {
        builder.Property(p => p.RowVersion)
            .IsRowVersion();
    }
}

Setup.cs

private static async Task Setup(Guid productId)
{
    await using var db = new DataContext();

    var product = await db.Products.FirstOrDefaultAsync(p => p.Id == productId);

    if (product == null)
    {
        product = new Product()
        {
            Id = productId
        };

        await db.Products.AddAsync(product);
    }

    product.Name = "product";
    product.Price = 10;

    await db.SaveChangesAsync();
}