Obtaining the last level of a json tree on php - php

Question

I have a json tree with categories,
I would like to obtain the last level of elements for each different category.
For example on this json:
[
{
"category_id": "3",
"parent_id": "2",
"name": "Women",
"categories": [
{
"category_id": "11",
"parent_id": "3",
"name": "Clothing",
"categories": [
{
"category_id": "30",
"parent_id": "11",
"name": "T-shirts",
"categories": null
},
{
"category_id": "33",
"parent_id": "11",
"name": "jeans",
"categories": null
}
]
}
]
},
{
"category_id": "5",
"parent_id": "2",
"name": "Footwear ",
"categories": [
{
"category_id": "15",
"parent_id": "5",
"name": "Rings",
"categories": [
{
"category_id": "51",
"parent_id": "15",
"name": "Small Leathers",
"categories": null
}
]
},
{
"category_id": "16",
"parent_id": "5",
"name": "Bands",
"categories": [
{
"category_id": "41",
"parent_id": "16",
"name": "boots",
"categories": null
}
]
},
{
"category_id": "48",
"parent_id": "5",
"name": "Bracelets",
"categories": [
{
"category_id": "55",
"parent_id": "48",
"name": "Cocktail",
"categories": null
}
]
}
]
}
]
The result would be an array (T-shirts, Jeans, Small Leathers, boots, cocktail)
What I was thinking is to decode it on an array and search filter the array with all the categories that are null, but I'm not sure if it's the best option because the object have different levels.
(I'm sorry for the English)

Answer 1

Json string is not a valid. It can be made valid by enclosing the json string in {}.
$json = '{"categories": [
{
"category_id": "3",
"parent_id": "2",
"name": "Women",
"categories": [
{
"category_id": "11",
"parent_id": "3",
"name": "Clothing",
"categories": [
{
"category_id": "30",
"parent_id": "11",
"name": "T-shirts",
"categories": null
},
{
"category_id": "33",
"parent_id": "11",
"name": "jeans",
"categories": null
}
]
}
]
},
{
"category_id": "5",
"parent_id": "2",
"name": "Footwear ",
"categories": [
{
"category_id": "15",
"parent_id": "5",
"name": "Rings",
"categories": [
{
"category_id": "51",
"parent_id": "15",
"name": "Small Leathers",
"categories": null
}
]
},
{
"category_id": "16",
"parent_id": "5",
"name": "Bands",
"categories": [
{
"category_id": "41",
"parent_id": "16",
"name": "boots",
"categories": null
}
]
},
{
"category_id": "48",
"parent_id": "5",
"name": "Bracelets",
"categories": [
{
"category_id": "55",
"parent_id": "48",
"name": "Cocktail",
"categories": null
}
]
}
]
}
]}';
Decode the json string in to php opject
$json_object = json_decode($json);
Use this recursive function to fetch get all the last level categories in a array.
function getLastCategories($object){
$last_categories = array();
if(is_array($object->categories)){
foreach($object->categories as $categories){
$last_categories = array_merge( $last_categories, getLastCategories($categories));
}
}else{
$last_categories[]=$object->name;
}
return $last_categories;
}
print_r(getLastCategories($json_object));
Output:
Array
(
[0] => T-shirts
[1] => jeans
[2] => Small Leathers
[3] => boots
[4] => Cocktail
)

Answer 2

You can do this using recursive iterators.
$categories = json_decode($json);
// create the iterator
$iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($categories));
// iterate recursively
foreach ($iterator as $key => $subcategories) {
// if the 'categories' key is empty for the current level...
if ($key == 'categories' && !$subcategories) {
// then add the value of the 'name' key for the current level to your result array.
$result[] = $iterator->getSubIterator()->offsetGet('name');
}
}
This may not be the most efficient way to do it, but it makes the code pretty simple.