In my previous blog, I have explained how to group data present in a XML file and transform the output into a new XML file. In this blog I will transform the data into a custom Object. I will be using the same XML file Products that I used in my previous blog, here is the link for my previous blog: Grouping Data in XML File using LINQ-XML.
Now, I want to group the products data by category and store the results into following custom type:
  1. public class Product
  2. {
  3. public int ProductId { get; set; }
  4. public string ProductName { get; set; }
  5. public decimal Price { get; set; }
  6. public string Color { get; set; }
  7. }
  9. public class ProductsByCategoty
  10. {
  11. public string Category { get; set; }
  12. public List<Product> ProductsUnderEachCategory { get; set; }
  13. }
As you can see, the class design is straight forward, since we are grouping the products by category. In the ProductsByCategory class we have a property Category and since each category may have multiple products, we have a second property that will be a List of Product classes.

Here is the LINQ query to do that.
1. Method Syntax:
  1. List<ProductsByCategoty> productsByCategotyMS = products.Root.Descendants("Product")
  2. .GroupBy(p => p.Element("Category").Value)
  3. .Select(p => new ProductsByCategoty
  4. {
  5. Category = p.Key,
  6. ProductsUnderEachCategory = (p.Select(x => new Product
  7. {
  8. ProductId = Convert.ToInt32(x.Element("ID").Value),
  9. ProductName = x.Element("Name").Value,
  10. Price = Convert.ToDecimal(x.Element("Price").Value),
  11. Color = x.Element("Color").Value
  12. })).ToList()
  13. }).ToList();
2. Query Syntax:
  1. List<ProductsByCategoty> productsByCategotyQS = (from p in products.Root.Descendants("Product")
  2. group p by p.Element("Category").Value into g
  3. select new ProductsByCategoty
  4. {
  5. Category = g.Key,
  6. ProductsUnderEachCategory = (from x in g
  7. select new Product
  8. {
  9. ProductId = Convert.ToInt32(x.Element("ID").Value),
  10. ProductName = x.Element("Name").Value,
  11. Price = Convert.ToDecimal(x.Element("Price").Value),
  12. Color = x.Element("Color").Value
  13. }).ToList()
  14. }).ToList();
Now, we can simply fetch the output using a nested foreach loop:
  1. foreach (var item in productsByCategotyQS)
  2. {
  3. Console.WriteLine("Category: {0}", item.Category);
  4. foreach (var pro in item.ProductsUnderEachCategory)
  5. {
  6. Console.WriteLine("ProductId: {0}, Name: {1}, Price: {2}, Color: {3}",
  7. pro.ProductId, pro.ProductName, pro.Price, pro.Color);
  8. }
  9. Console.WriteLine("-------------------------------------------------------");
  10. }
Please let me know in case of any issues. Happy Coding :)