cs11dotnet7/vscode/Chapter10/WorkingWithEFCore/Northwind.cs

using Microsoft.EntityFrameworkCore; // DbContext, DbContextOptionsBuilder
using Microsoft.EntityFrameworkCore.Diagnostics;

namespace Packt.Shared;

// this manages the connection to the database
public class Northwind : DbContext
{
  // these properties map to tables in the database
  public DbSet<Category>? Categories { get; set; }
  public DbSet<Product>? Products { get; set; }

  protected override void OnConfiguring(
    DbContextOptionsBuilder optionsBuilder)
  {
    string path = Path.Combine(
      Environment.CurrentDirectory, "Northwind.db");

    string connection = $"Filename={path}";

    ConsoleColor previousColor = ForegroundColor;
    ForegroundColor = ConsoleColor.DarkYellow;
    WriteLine($"Connection: {connection}");
    ForegroundColor = previousColor;

    optionsBuilder.UseSqlite(connection);

    optionsBuilder.LogTo(WriteLine, // Console
      new[] { RelationalEventId.CommandExecuting }) 
      .EnableSensitiveDataLogging();

    optionsBuilder.UseLazyLoadingProxies();
  }

  protected override void OnModelCreating(
    ModelBuilder modelBuilder)
  {
    // example of using Fluent API instead of attributes
    // to limit the length of a category name to 15
    modelBuilder.Entity<Category>()
      .Property(category => category.CategoryName)
      .IsRequired() // NOT NULL
      .HasMaxLength(15);

    if (Database.ProviderName?.Contains("Sqlite") ?? false)
    {
      // added to "fix" the lack of decimal support in SQLite
      modelBuilder.Entity<Product>()
        .Property(product => product.Cost)
        .HasConversion<double>();
    }

    // global filter to remove discontinued products
    modelBuilder.Entity<Product>()
      .HasQueryFilter(p => !p.Discontinued);
  }
}