10.4 Querying EF Core models -> use LINQ to query all categories and their products

Chapter10/WorkingWithEFCore/WorkingWithEFCore/Program.cs

@@ -1,3 +1,26 @@
-using Packt.Shared;
+using Microsoft.EntityFrameworkCore;
+using Packt.Shared;
 
-Console.WriteLine($"Using {ProjectConstants.DatabaseProvider} database provider.");
+Console.WriteLine($"Using {ProjectConstants.DatabaseProvider} database provider.");
+QueryingCategories();
+
+static void QueryingCategories()
+{
+    using (Northwind db = new())
+    {
+        Console.WriteLine("Categories and how many products they have:");
+        // a query to get all categories and their related products
+        IQueryable<Category>? categories = db.Categories?
+            .Include(c => c.Products);
+        if (categories is null)
+        {
+            Console.WriteLine("No categories found");
+            return;
+        }
+        // execute query and enumerate results
+        foreach (var c in categories)
+        {
+            Console.WriteLine($"{c.CategoryName} has {c.Products.Count} products");
+        }
+    }
+}