LINQ recursion function?

by

LINQ doesn’t really “do” recursion nicely. Your solution seems appropriate – although I’m not sure HasChildren is really required… why not just use an empty list for an item with no children?

An alternative is to write a DescendantsAndSelf method which will return all of the descendants (including the item itself), something like this;

// Warning: potentially expensive!
public IEnumerable<SomeItem> DescendantsAndSelf()
{
    yield return this;
    foreach (var item in Children.SelectMany(x => x.DescendantsAndSelf()))
    {
        yield return item;
    }
}

However, if the tree is deep that ends up being very inefficient because each item needs to “pass through” all the iterators of its ancestry. Wes Dyer has blogged about this, showing a more efficient implementation.

Anyway, if you have a method like this (however it’s implemented) you can just use a normal “where” clause to find an item (or First/FirstOrDefault etc).

More Related Contents:

  1. Fun (?) with Linq Expressions in extension methods
  2. Convert this sql command to c# linq
  3. How to click in imagelink in gridview and go to another gridview
  4. LINQ equivalent of foreach for IEnumerable
  5. Is it possible to Pivot data using LINQ?
  6. C# LINQ find duplicates in List
  7. What are the benefits of a Deferred Execution in LINQ?
  8. Entity framework linq query Include() multiple children entities
  9. How can I do an OrderBy with a dynamic string parameter?
  10. LINQ to Entities does not recognize the method ‘System.String Format(System.String, System.Object, System.Object)’
  11. System.LINQ.Dynamic: Select(” new (…)”) into a List (or any other enumerable collection of )
  12. LINQ OrderBy versus ThenBy
  13. LINQ: Dot Notation vs Query Expression
  14. Learning about LINQ [closed]
  15. What’s the difference between IQueryable and IEnumerable [duplicate]
  16. Standard Deviation in LINQ
  17. Can LINQ be used in PowerShell?
  18. How To Project a Line Number Into Linq Query Results
  19. Calculate difference from previous item with LINQ
  20. Use LINQ to concatenate multiple rows into single row (CSV property)
  21. LINQ with SQLite (linqtosql)
  22. How to create a dynamic LINQ join extension method
  23. PowerShell equivalent of LINQ Any()?
  24. Instantiating a context in LINQ to Entities
  25. conditional include in linq to entities?
  26. Recursive LINQ query: select item and all children with subchildren
  27. Linq To Entities – how to filter on child entities
  28. Is there a pattern using Linq to dynamically create a filter?
  29. Simple Linq query has duplicated join against same table?
  30. Linq to SQL how to do “where [column] in (list of values)”

Leave a Comment