Question

Having these 2 classes and this linq request:

var cats = from c in xml.Descendants("category")
           let categoryName = c.Attribute("name").Value
           let descendants = c.Descendants()
           select new Category
           {
                Name = categoryName,
                Items = from d in descendants
                        let typeId = d.Attribute("id").Value
                        select new Item
                        {
                            Id = typeId,
                            Name = d.Value,
                            Category = ???????
                        }
           };

class Category
{
    string Name;
    IEnumerable<Item> Items;
}

class Item
{
    string Id;
    string Name;
    Category Category;
}

How can I affect the item’s category to the current selected category?
A kind of a keyword like this maybe?

Answer 1

Time for a recursion! Simply wrap the function getting the Category and then just call it when needed.

public static IQueryable<Category> GetCategories(string catName, XDocument xml)
{
      var cats = from c in xml.Descendants("category")
                 let categoryName = c.Attribute("name").Value
                 let descendants = c.Descendants()
                 where (catName == "" || categoryName == catName)
                 select new Category
                 {
                      Name = categoryName,
                      Items = from d in descendants
                              let typeId = d.Attribute("id").Value
                              select new Item
                              {
                                  Id = typeId,
                                  Name = d.Value,
                                  Category = GetCategories(categoryName, xml).FirstOrDefault()
                              }
                };

       return cats.AsQueryable();
}

And you call it like this:

XDocument xml = XDocument.Parse(...); // parse the xml file
IQueryable<Category> cats = GetCategories("", xml);

First load of the function calls uses empty string as category name, because we don’t need to filter the results. Then we recursively call the same function, but filtering by category name. Give it a try, worked for me.