Retrieve data hierarchically in Entity Framework - entity-framework

Question

I have a structure of 'Folder' entities. Each Folder has a reference to its parent Folder, allowing for a standard tree structure. Each folder can also have a collection of items, let's call them 'Articles'. An article has a title and a body. Given the ID of a root folder, I want to retrieve all the subfolders and their articles. However, I want to only retrieve the article title, not its body. I intend to display the folder structure in a tree view, and I want to retrieve the full article only if the user selects the article in the tree view.
I have set up the relations like so:
public class Folder: EntityBase
{
public string Name { get; set; }
public Guid ParentId { get; set; }
[ForeignKey(nameof(ParentId))]
public Folder Parent { get; set; }
public ICollection<Folder> Folders { get; set; }
public ICollection<Article> Articles { get; set; }
}
public class Article : EntityBase
{
public Guid FolderId { get; set; }
[ForeignKey(nameof(FolderId))]
public Folder Folder { get; set; }
// this needs to appear in the list
public string Title { get; set; }
// potentially large amount of data, retrieve only as necessary
public string Body { get; set; }
...
}
What I can't figure out is how to tell Entity Framework to recursively go through all the subfolders and their subfolders and so on. Do I have to implement recursion in my code? That seems a bit inefficient. Is there a preferred way to handle this?
Also, how do I retrieve just the title field of my articles, not the whole body?

Answer 1

Do I have to implement recursion in my code
The alternative recursively loading from the client is load all the Folders with a single query, and let EF fix-up the relationships. If you don't want to load all the Folders, you can perhaps use a SQL query to just the Folders under a particular Folder (eg using a recursive CTE).
how do I retrieve just the title field of my articles, not the whole body
EF doesn't support partially loading a single Entity, but you can use "Table Splitting" to split ArticleBody into a separate Entity, even if it is on the same table.