php add and merge data from two table - php

Question

I have this query from first table:
$this->db->table('categories')
->select('id, name, parent_id')
->orderBy('parent_id')
->get()
->getResultObject();
data output is:
Array
(
[0] => stdClass Object
(
[id] => 1
[name] => cat1
[parent_id] => 0
)
[1] => stdClass Object
(
[id] => 2
[name] => cat2
[parent_id] => 0
)
[2] => stdClass Object
(
[id] => 5
[name] => cat5
[parent_id] => 0
)
[3] => stdClass Object
(
[id] => 6
[name] => cat6
[parent_id] => 0
)
[4] => stdClass Object
(
[id] => 3
[name] => cat3
[parent_id] => 2
)
[5] => stdClass Object
(
[id] => 4
[name] => cat4
[parent_id] => 2
)
)
and query for second table:
$this->db->table('post_category')
->select('category_id')
->where('post_id', $id)
->get()->getResultObject();
output data is:
Array
(
[0] => stdClass Object
(
[category_id] => 1
)
[1] => stdClass Object
(
[category_id] => 4
)
)
Now I need to add selected in array and add data(category_id) from table two in table one if (category_id = id) like this:
Array
(
[0] => stdClass Object
(
[id] => 1
[name] => cat1
[parent_id] => 0
[selected] => 1
)
[1] => stdClass Object
(
[id] => 2
[name] => cat2
[parent_id] => 0
[selected] =>
)
[2] => stdClass Object
(
[id] => 5
[name] => cat5
[parent_id] => 0
[selected] =>
)
[3] => stdClass Object
(
[id] => 6
[name] => cat6
[parent_id] => 0
[selected] =>
)
[4] => stdClass Object
(
[id] => 3
[name] => cat3
[parent_id] => 2
[selected] =>
)
[5] => stdClass Object
(
[id] => 4
[name] => cat4
[parent_id] => 2
[selected] => 1
)
)
How do can i add data from table two in table one(if category_id from table two = id from table one) like my last output?!

Answer 1

If you just want to populate the ['selected'] item of a subarray in the first array ("categories") with "1" based on whether there's a "post_category" with that value you can do this:
foreach ($categories as &$category) {
$filtered_post_categories = array_filter($post_categories, function($post_category) use ($category) {
return $post_category->category_id == $category->id;
});
if (count($filtered_post_categories) > 0) {
$category->selected = 1;
}
else {
$category->selected = null;
}
}