Question

I want to write an elegant linq query to handle the following SAMPLE object model:

    class Category     {         public string Name { get; set; }                 public IList<Product> Products { get; set;}             }      class Product     {         public string Title { get; set; }         public IList<Photo> Photos { get; set; }     }      class Photo     {         public int Id { get; set; }     } 

I constructed the following query to get the Photo Id:

    var query = from category in Factory.GetCategories()                 where category.Name == 'Cameras'                 select (from product in category.Products                         where product.Title == 'Sony'                         select (from photo in product.Photos                                 select photo.Id)                                );      var v = query.ToList(); 

At the moment the query does not project correctly i have to add a FirstOrDefault() to each of the Sub Selects!:

var query = from category in Factory.GetCategories()                 where category.Name == 'Cameras'                 select (from product in category.Products                         where product.Title == 'Sony'                         select (from photo in product.Photos                                 select photo.Id).FirstOrDefault()                                ).FirstOrDefault();  var v = query.ToList(); 

Is there a better way to do this? Ignoring the fact that we are not dealing with a database and PK’s/FK’s are not in play.

I really want to avoid writing a big for loop when i could do the same thing in a linq query:

foreach (var category in Factory.GetCategories())             {                 if (category.Name == 'Camera')                 {                     foreach (var product in category.Products)                     {                         if (product.Title == 'Sony')                         {                             foreach (var photo in product.Photos)                             {                                 //get data                                 int id = photo.Id;                             }                         }                     }                 }                             } 

The actual implementation is more complex than this simple object model. I want to get the basic idea from this simple sample so i apply it to my real object model.

Cheers!

Answer 1

Do you just want the flattened ids?

        var query = from category in Factory.GetCategories()                     where category.Name == 'Cameras'                     from product in category.Products                     where product.Title == 'Sony'                     from photo in product.Photos                     select photo.Id;