Recursive iterators expose nested data one level at a time, while RecursiveIteratorIterator can flatten a hierarchy for traversal.
What Is RecursiveCallbackFilterIterator::getChildren in PHP?
Gets a child iterator for the currently selected nested entry.
RecursiveCallbackFilterIterator::getChildren()This operation does not accept method arguments.
Example 1: Understanding the Basic Behavior
<?php
$source = new RecursiveArrayIterator(["group" => [1,2], "status" => "active"]);
$iterator = new RecursiveCallbackFilterIterator($source, static fn($current, $key, $iterator): bool => true);
$iterator->rewind();
var_dump($iterator->getChildren());The output includes runtime-dependent object or source details, so it may differ across PHP installations.
Explanation: Gets a child iterator for the currently selected nested entry.
Example 2: Testing Another Case
<?php
$source = new RecursiveArrayIterator(["folder" => [3,4], "state" => "pending"]);
$iterator = new RecursiveCallbackFilterIterator($source, static fn($current, $key, $iterator): bool => true);
$iterator->rewind();
var_dump($iterator->getChildren());The output includes runtime-dependent object or source details, so it may differ across PHP installations.
Explanation: A child iterator is valid only when the current entry has children.
Practical Example: Applying the Operation
<?php
$source = new RecursiveArrayIterator(["items" => [5,6], "mode" => "ready"]);
$iterator = new RecursiveCallbackFilterIterator($source, static fn($current, $key, $iterator): bool => true);
$iterator->rewind();
var_dump($iterator->getChildren());The output includes runtime-dependent object or source details, so it may differ across PHP installations.
Explanation: Child operations are meaningful only for nested entries; traversal mode determines which keys and depths appear.
Important Behavior and Edge Cases
- A child iterator is valid only when the current entry has children.
- Child operations are meaningful only for nested entries; traversal mode determines which keys and depths appear.
Comparison With Related Approaches
| Approach | When to Use It |
|---|---|
RecursiveCallbackFilterIterator::getChildren | Gets a child iterator for the currently selected nested entry. |
ArrayIterator | RecursiveArrayIterator exposes nested arrays, while RecursiveIteratorIterator walks through the nested levels. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Assuming RecursiveCallbackFilterIterator::getChildren() works on every scalar entry without inspecting the current traversal depth. | A child iterator is valid only when the current entry has children. |
| Choosing ArrayIterator without checking whether it provides the same result. | RecursiveArrayIterator exposes nested arrays, while RecursiveIteratorIterator walks through the nested levels. |
Key Takeaways
- Gets a child iterator for the currently selected nested entry.
- A child iterator is valid only when the current entry has children.
- Child operations are meaningful only for nested entries; traversal mode determines which keys and depths appear.
The examples demonstrate where RecursiveCallbackFilterIterator::getChildren fits within nested iteration. Verify the relevant preconditions whenever you adapt the code to real data.