c# - How to get a flattened list from nested class List? -

c# - How to get a flattened list from nested class List<T>? -

i have question using these same examples - question focused on different issue. given next classes:

[xmlroot] public class family { [xmlelement] public list<person> person; } public class person { [xmlattribute("member")] public membertype fellow member { get; set; } [xmlattribute("id")] public int id { get; set; } [xmlelement] public string surname { get; set; } [xmlelement] public string forename { get; set; } [xmlelement("person")] public list<person> people; } public enum membertype { father, mother, son, girl }

if family has method defined such:

public ienumerable<person> find (func<person, bool> predicate) { // how selectmany flatten list? foreach (var p in family.person.selectmany(p => p)) { if(predicate(p)) { yield homecoming p; } } }

i need able execute predicate on flattened list of person. in illustration above selectmany not flattening list had hoped. above won't compile because inferred type cannot determined.

how can family.person collection become 1 flattened list of person?

public ienumerable<person> find(ienumerable<person> input, func<person, bool> predicate) { homecoming input.select(p => { var thislevel = new list<person>(); if(predicate(p)) thislevel.add(p); homecoming thislevel.union(find(p.people ?? new list<person>(), predicate)); } ).selectmany(p => p); }

c# linq-to-objects