CODEWITHSUNDEEP
c#linqsorting
user3293835
user3293835

Reputation: 899

How to sort nested items?

I have a plain list of persons List<Person>

public class Person
{
    public int Id { get; set; }

    public int ParentId { get; set; }

    public List<Person> Childs { get; set; }
}

so I want to sort it to have a list of persons without a ParentId and all children of a person are added to his Childs. I've no idea how to do it, any tips?

Upvotes: 0

Views: 182

Answers (2)

Enigmativity
Enigmativity

Reputation: 117029

This should work a treat:

var lookup = people.ToLookup(p => p.ParentId);

foreach (var person in people)
{
    person.Childs = lookup[person.Id].ToList();
}

If the Childs collection is already instantiated then use this:

    person.Childs.AddRange(lookup[person.Id]);

Upvotes: 1

MarcinJuraszek
MarcinJuraszek

Reputation: 125620

I'm not sure what you're asking for, but seems like you're trying to get tree-like structure form single-dimmentional list of Person. 

var dict = source.ToDictionary(x => x.Id);

foreach(var p in source)
    if(p.ParentId != 0)
        dict[p.ParentId].Childs.Add(p);

var topLevel = source.Where(p => p.ParentId == 0).ToList();

I assumed ParentId == 0 means there is no parent, and that item is top level item.

Upvotes: 1

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