Linq with EF, include specific columns - sql

Question

I have two classes:
public class Category
{
public int Id { get; set; }
[Required]
[MaxLength(255)]
public string Name { get; set; }
public int? CategoryId { get; set; }
public double Weight { get; set; }
public ICollection<Article> Articles { get; set; }
public bool Hidden { get; set; }
}
public class Article
{
public int Id { get; set; }
[StringLength(255)]
public string Title { get; set; }
public string Body { get; set; }
public double Weight { get; set; }
public Category Category { get; set; }
public int? CategoryId { get; set; }
}
I would like to select some Categories including Articles, but without Article.Body. Method syntax is more preferred.
Something like:
IEnumerable<Category> categories = _context
.Categories
.Where(c => c.Hidden == false)
.Include(c => c.Articles)
.OrderBy(c => c.Weight);
Not sure how to specify which columns exactly to select (eagerly) on the included Articles.

Answer 1

Include doesn't allow projections, you can only include complete entities.
But there is a way out.
This is a typical case that you should solve by table splitting. By table splitting you "split" a table over two (or more) entities, so it's easier to filter e.g. light data from heavy data or public data from secure data.
In your case the class model (for Article) would look like this:
public class Article
{
public int Id { get; set; }
[StringLength(255)]
public string Title { get; set; }
public double Weight { get; set; }
public Category Category { get; set; }
public int? CategoryId { get; set; }
public virtual ArticleBody ArticleBody { get; set; }
}
public class ArticleBody
{
public int Id { get; set; }
public string Text { get; set; }
}
And the mappings:
modelBuilder.Entity<Article>()
.HasRequired(a => a.ArticleBody)
.WithRequiredPrincipal();
modelBuilder.Entity<Client>().ToTable("Article");
modelBuilder.Entity<ArticleBody>().ToTable("Article");
Now if you do...
_context.Categories
.Where(c => !c.Hidden)
.Include(c => c.Articles)
...you'll see that only Articles without body texts will be selected in the generated SQL.
If you want the body as well, you do
_context.Categories
.Where(c => !c.Hidden)
.Include(c => c.Articles.Select(a => a.ArticleBody))

Answer 2

Sorry if i did not understand your question, but I think you can specify what columns you want in your select statement.
Simple example:
var query = from c in Categories
select c.Name, c.CategoryId;