How to sort Self-referencing table or entities - wpf

Question

I have two entity look like this.
public class Post{
[Key]
public int Id { get; set; }
[Required(ErrorMessage = "")]
[MaxLength(100, ErrorMessage = "")]
public string Name { get; set; }
[ForeignKey("ParentPost")]
public int? ParentPostId { get; set; }
public virtual Post ParentPost { get; set; }
public ICollection<Post> SubPosts { get; set; }
}
public class User{
[Key]
public int Id { get; set; }
[Required(ErrorMessage = "")]
[MaxLength(100, ErrorMessage = "")]
public string Name { get; set; }
[ForeignKey("Post")]
public int PostId { get; set; }
public virtual Post Post { get; set; }
}
I have a list of Users, I want sort Users with level of Post.
for example :
ID---------Name------ParentID
1----------1-----------NULL
2----------1.1----------1
3----------2-----------NULL
4----------1.1.1--------2
5----------1.2----------3
Sort By Level.
1
2
1.1
1.2
1.1.1

Answer 1

UPDATE :
Here is an alternative to my previous answer that don't need you to add properties in Post. Create extension method for Post entity to count level and number based on Post's Name. I assume you give it a consistent naming.
public static class ExtensionMethods
{
public static int Level(this Post post)
{
var name = post.Name;
var level = 0;
level = name.Count(o => o == '.');
return level;
}
public static int number(this Post post)
{
var name = post.Name;
var number = 0;
var split = name.Split('.');
return split.Length > 1 ? int.Parse(split[split.Length - 1]) : int.Parse(name);
}
}
Then you can sort using linq like:
var posts = new List<Post>();
posts.Add(new Post { Name = "1.2" });
posts.Add(new Post { Name = "1.1.1" });
posts.Add(new Post { Name = "2" });
posts.Add(new Post { Name = "1.1" });
posts.Add(new Post { Name = "1" });
foreach (var post in posts)
{
Console.WriteLine(post.Name);
}
Console.WriteLine("\n\nAfter sorting");
var sorted = posts.OrderBy(p => p.Level()).ThenBy(p => p.number());
foreach (var post in sorted)
{
Console.WriteLine(post.Name);
}
PREVIOUS ANSWER :
I can't think of proper solution with current properties of Post entity. I thought of some logic but those aren't perfect, will break in some conditions.
The proper solution I can think is require adding two more properties in Post. Level property to store Post level, and Number property to store the number after last point in Name (1 for post name 1.1.1, 10 for post name 2.1.10, etc..). With those two additional properties you can sort Post like following:
Posts.OrderBy(p => p.Level)
.ThenBy(p => p.Number);