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Convert a DB result of parent/child items into a hierarchical array
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| <?php | |
| // -- Only one caveat : The results must be ordered so that an item's parent will be processed first. | |
| // -- Simulate a DB result | |
| $results = array(); | |
| $results[] = array('id' => 'a', 'parent' => '', 'name' => 'Johnny'); | |
| $results[] = array('id' => 'b', 'parent' => 'a', 'name' => 'Bobby'); | |
| $results[] = array('id' => 'c', 'parent' => 'b', 'name' => 'Marky'); | |
| $results[] = array('id' => 'd', 'parent' => 'a', 'name' => 'Ricky'); | |
| $results[] = array('id' => 'e', 'parent' => '', 'name' => 'Timmy'); | |
| $results[] = array('id' => 'g', 'parent' => 'f', 'name' => 'Mary'); // -- child showing before parent, to demonstrate shuffling after initial pass | |
| $results[] = array('id' => 'f', 'parent' => 'e', 'name' => 'Tommy'); | |
| $results[] = array('id' => 'h', 'parent' => 'b', 'name' => 'Donny'); | |
| function convertToHierarchy($results) { | |
| $hierarchy = array(); // -- Stores the final data | |
| $itemReferences = array(); // -- temporary array, storing references to all items in a single-dimention | |
| foreach ( $results as $item ) { | |
| $parent = $item['parent']; | |
| if (isset($itemReferences[$parent])) { // parent exists | |
| $itemReferences[$parent]['children'][$item['id']] = $item; // assign item to parent | |
| $itemReferences[$item['id']] =& $itemReferences[$parent]['children'][$item['id']]; // reference parent's item in single-dimentional array | |
| } elseif (!$parent || !isset($hierarchy[$parent])) { // -- parent value is empty. It is a root item | |
| $hierarchy[$item['id']] = $item; | |
| $itemReferences[$item['id']] =& $hierarchy[$item['id']]; | |
| } | |
| } | |
| // -- Run through the root one more time. If any child got added before it's parent, fix it. | |
| foreach ( $hierarchy as $id => &$h ) { | |
| if ( isset($itemReferences[$h['parent']] ) ) { // -- parent DOES exist | |
| $itemReferences[$h['parent']]['children'][$h['id']] = $h; // -- assign it to the parent's list of children | |
| unset($hierarchy[$id]); // -- remove it from the root of the hierarchy | |
| } | |
| } | |
| unset($itemReferences, $item, $results, $parent); | |
| return $hierarchy; | |
| } | |
| print_r(convertToHierarchy($results)); | |
| ?> |
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