Entity Framework Core Setup Guide

Step 1-4: Add Required NuGet Packages

Add these packages to your project via Package Manager UI or Package Manager Console:

<PackageReference Include="Microsoft.EntityFrameworkCore" Version="8.0.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="8.0.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="8.0.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="8.0.0" />

Package Purposes:

• EntityFrameworkCore: Core EF functionality
• EntityFrameworkCore.Design: Design-time tools for migrations
• EntityFrameworkCore.SqlServer: SQL Server database provider
• EntityFrameworkCore.Tools: Package Manager Console commands

Step 5: Write POCOs and DataContext

Example POCOs.cs

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace YourProject.Models
{
    // Product POCO
    public class Product
    {
        [Key]
        public int ProductId { get; set; }

        [Required]
        [MaxLength(100)]
        public string Name { get; set; }

        [Column(TypeName = "decimal(18,2)")]
        public decimal Price { get; set; }

        public string Description { get; set; }

        public int CategoryId { get; set; }

        // Navigation property
        public virtual Category Category { get; set; }
    }

    // Category POCO
    public class Category
    {
        [Key]
        public int CategoryId { get; set; }

        [Required]
        [MaxLength(50)]
        public string Name { get; set; }

        // Navigation property
        public virtual ICollection<Product> Products { get; set; }
    }

    // Order POCO
    public class Order
    {
        [Key]
        public int OrderId { get; set; }

        public DateTime OrderDate { get; set; }

        [Required]
        [MaxLength(100)]
        public string CustomerName { get; set; }

        [Column(TypeName = "decimal(18,2)")]
        public decimal TotalAmount { get; set; }

        // Navigation property
        public virtual ICollection<OrderItem> OrderItems { get; set; }
    }

    // OrderItem POCO
    public class OrderItem
    {
        [Key]
        public int OrderItemId { get; set; }

        public int OrderId { get; set; }
        public int ProductId { get; set; }
        public int Quantity { get; set; }

        [Column(TypeName = "decimal(18,2)")]
        public decimal UnitPrice { get; set; }

        // Navigation properties
        public virtual Order Order { get; set; }
        public virtual Product Product { get; set; }
    }
}

DataContext

using Microsoft.EntityFrameworkCore;
using YourProject.Models;

namespace YourProject.Data
{
    public class ApplicationDbContext : DbContext
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
            : base(options)
        {
        }

        // DbSets for each entity
        public DbSet<Product> Products { get; set; }
        public DbSet<Category> Categories { get; set; }
        public DbSet<Order> Orders { get; set; }
        public DbSet<OrderItem> OrderItems { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);

            // Configure relationships
            modelBuilder.Entity<Product>()
                .HasOne(p => p.Category)
                .WithMany(c => c.Products)
                .HasForeignKey(p => p.CategoryId);

            modelBuilder.Entity<OrderItem>()
                .HasOne(oi => oi.Order)
                .WithMany(o => o.OrderItems)
                .HasForeignKey(oi => oi.OrderId);

            modelBuilder.Entity<OrderItem>()
                .HasOne(oi => oi.Product)
                .WithMany()
                .HasForeignKey(oi => oi.ProductId);

            // Seed data (optional)
            modelBuilder.Entity<Category>().HasData(
                new Category { CategoryId = 1, Name = "Electronics" },
                new Category { CategoryId = 2, Name = "Books" }
            );
        }
    }
}

Connection String Configuration

Add to appsettings.json:

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=(localdb)\\\\mssqllocaldb;Database=YourProjectDb;Trusted_Connection=true;MultipleActiveResultSets=true"
  }
}

Register in Program.cs (or Startup.cs):

builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));

Step 6: Compile Code