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vscode/Chapter10/Ch10Ex02DataSerialization/Northwind.cs

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+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);
+  }
+
+  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>();
+    }
+  }
+}