Entity Framework Setup for .NET Web Application

Entity Framework Core Setup for .NET Web Application

Entity Framework Core is the primary ORM for .NET 6+. Unlike classic EF, EF Core is written from scratch, supports PostgreSQL via Npgsql, runs without GAC, and installs as NuGet package.

Installation

dotnet add package Microsoft.EntityFrameworkCore
dotnet add package Npgsql.EntityFrameworkCore.PostgreSQL
dotnet add package Microsoft.EntityFrameworkCore.Design
dotnet tool install --global dotnet-ef

DbContext

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

    public DbSet<User> Users => Set<User>();
    public DbSet<Product> Products => Set<Product>();
    public DbSet<Order> Orders => Set<Order>();

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfigurationsFromAssembly(typeof(AppDbContext).Assembly);
        modelBuilder.Entity<Product>()
            .HasQueryFilter(p => !p.IsDeleted);
    }
}

DI Registration

builder.Services.AddDbContext<AppDbContext>(options =>
{
    options.UseNpgsql(
        builder.Configuration.GetConnectionString("Default"),
        npgsqlOptions =>
        {
            npgsqlOptions.CommandTimeout(30);
            npgsqlOptions.EnableRetryOnFailure(maxRetryCount: 3);
        }
    );
});

Model

public class Product
{
    public int Id { get; set; }
    public string Title { get; set; } = default!;
    public string Slug { get; set; } = default!;
    public decimal Price { get; set; }
    public ProductStatus Status { get; set; } = ProductStatus.Draft;
    public int CategoryId { get; set; }
    public Category Category { get; set; } = default!;
    public ICollection<Tag> Tags { get; set; } = new List<Tag>();
    public DateTime CreatedAt { get; set; }
    public DateTime UpdatedAt { get; set; }
}

Configuration

public class ProductConfiguration : IEntityTypeConfiguration<Product>
{
    public void Configure(EntityTypeBuilder<Product> builder)
    {
        builder.ToTable("products");
        builder.HasKey(p => p.Id);

        builder.Property(p => p.Title).HasMaxLength(500).IsRequired();
        builder.Property(p => p.Slug).HasMaxLength(520).IsRequired();
        builder.HasIndex(p => p.Slug).IsUnique();

        builder.HasOne(p => p.Category)
            .WithMany(c => c.Products)
            .HasForeignKey(p => p.CategoryId)
            .OnDelete(DeleteBehavior.Restrict);

        builder.HasMany(p => p.Tags)
            .WithMany(t => t.Products)
            .UsingEntity(j => j.ToTable("product_tags"));
    }
}

Queries

public async Task<List<Product>> GetPublishedAsync(
    int categoryId,
    int page = 1,
    int pageSize = 24,
    CancellationToken ct = default)
{
    return await _db.Products
        .AsNoTracking()
        .Include(p => p.Category)
        .Include(p => p.Tags)
        .Where(p => p.CategoryId == categoryId && p.Status == ProductStatus.Published)
        .OrderByDescending(p => p.CreatedAt)
        .Skip((page - 1) * pageSize)
        .Take(pageSize)
        .ToListAsync(ct);
}

Migrations

dotnet ef migrations add CreateProducts
dotnet ef database update
dotnet ef migrations script --idempotent --output migrations.sql

Timeline

Initial EF Core setup: 1 day. Optimization: 1–2 days.