Not loading a child property into memory - entity-framework-core

Question

I have the following Entities on Entity Framework Core 2.2:
public class Post {
public Int32 Id { get; set; }
public string Type { get; set; }
public virtual Collection<File> Files { get; set; }
}
public class File {
public Int32 Id { get; set; }
public Int32 PostId { get; set; }
public String Name { get; set; }
public Byte[] Content { get; set; }
public virtual Post Post { get; set; }
}
I need to get the list of files Ids and Names of a Post without loading their Content into Memory.
IQueryable<Post> posts = _context.Posts.AsNoTracking();
posts = posts.Include(x => x.File);
var files = await posts
.Where(x => x.Type == "design")
// Remaining Query
I think the moment I use Include the files will be loaded into memory. No?
What is the correct way to get a list of Posts' Files Ids and Names without loading their Content into Memory?

Answer 1

I need to get the list of files Ids and Names of a Post without loading their Content into Memory.
What is the correct way to get a list of Posts' Files Ids and Names without loading their Content into Memory?
Once you said you want to get a Post and then said you want to get a list of Post.
So to get a Post with its files (only Id and Name) you can write your query as follows:
var post = await _context.Posts.Where(yourCondition).Select(p => new
{
p.Id,
p.Type
Files = p.Files.Select(f => new {f.Id,f.Name}).ToList()
}).FirstOrDefaultAsync();
And to get list of Posts with its files (only Id and Name) you can write your query as follows:
var posts = await _context.Posts.Where(yourCondition).Select(p => new
{
p.Id,
p.Type
Files = p.Files.Select(f => new {f.Id,f.Name}).ToList()
}).ToListAsync();
Note: If you need strongly typed then can write as follows:
Post post = await _context.Posts.Where(yourCondition).Select(p => new Post
{
Id = p.Id,
Type = p.Type
Files = p.Files.Select(f => new File {f.Id,f.Name}).ToList()
}).FirstOrDefaultAsync();