Active Record

Active Record is object-relational mapping (ORM) pattern. It integrates both business logic and data persistence within a single object.

In Active Record pattern, each object in the system directly corresponds to a row in a database table.

It makes Active Record very similar to the Row Gateway pattern, but the key difference between them is that Active Record saves and retrieves the entire object, while the Row Gateway pattern saves and retrieves raw database table data.

An object is an entity that has state, behavior, and identity.

Drawbacks

Leads to tightly coupled code between the domain model and the database.

Example

using Microsoft.EntityFrameworkCore;
using System.Collections.Generic;
using System.Linq;


namespace DomainLayer
{
    public class Product
    {
        public Product()
        {
            OrderProducts = [];
        }

        public int Id { get; set; }

        public string Name { get; set; }

        public decimal Price { get; set; }

        public virtual ICollection<OrderProduct> OrderProducts { get; set; }

        #region Data Access

        public async Task<bool> SaveAsync(MyDbContext context)
        {
            try
            {
                if (Id == 0)
                {
                    await context.AddAsync(this);
                }
                else
                {
                    context.Update(this);
                }

                await context.SaveChangesAsync();
                return true;
            }
            catch (Exception ex)
            {
                // Error saving Product .. 
                return false;
            }
        }

        public static async Task<List<Product>> GetAllAsync(MyDbContext context)
        {
            return await context.Products.ToListAsync();
        }

        public static async Task<Product?> GetByIdAsync(MyDbContext context, int id)
        {
            return await context.Products.FirstOrDefaultAsync(p => p.Id == id);
        }

        #endregion Data Access
    }

    public class Order
    {
        public Order()
        {
            OrderProducts = [];
        }
        public int Id { get; set; }

        public DateTime OrderDate { get; set; }

        public virtual ICollection<OrderProduct> OrderProducts { get; set; }


        #region Data Access

        public async Task<bool> SaveAsync(MyDbContext context)
        {
            try
            {
                if (Id == 0)
                {
                    await context.AddAsync(this);
                }
                else
                {
                    context.Update(this);
                }

                await context.SaveChangesAsync();
                return true;
            }
            catch (Exception ex)
            {
                // Error saving Order ..
                return false;
            }
        }

        public static async Task<List<Order>> GetAllAsync(MyDbContext context)
        {
            return await context.Orders.ToListAsync();
        }

        public static async Task<Order?> GetByIdAsync(MyDbContext context, int id)
        {
            return await context.Orders.FirstOrDefaultAsync(o => o.Id == id);
        }

        #endregion Data Access
    }

    public class OrderProduct
    {
        public int OrderId { get; set; }

        public int ProductId { get; set; }

        public int Quantity { get; set; }

        public virtual Order Order { get; set; }

        public virtual Product Product { get; set; }

        #region Data Access
        
        public async Task<bool> SaveAsync(MyDbContext context)
        {
            try
            {
                if (OrderId == 0 && ProductId == 0)
                {
                    await context.AddAsync(this);
                }
                else
                {
                    context.Update(this);
                }

                await context.SaveChangesAsync();
                return true;
            }
            catch (Exception ex)
            {
                // Error saving OrderProduct ..
                return false;
            }
        }

        #endregion Data Access
    }

    public class MyDbContext : DbContext
    {
        public DbSet<Product> Products { get; set; }
        public DbSet<Order> Orders { get; set; }
        public DbSet<OrderProduct> OrderProducts { get; set; }

        // ... (Constructor and DbContextOptions configuration) ...
    }
}

Table of Contents

Active Record

Drawbacks

Example