Adding categories & subcategories to a blog - php

Question

Ok, I have done lots of research and looked at lots of stackoverflow questions but none have answered my question.
I'm building a simple blog and am at the moment i'm trying to build a simple categories/subcategories system but have hit an obstacle in making the subcategories load under their parent. If you know an easier method to the one i am doing below please let me know.
Here is how my db is structured:
id || name || parent_id || status
------------------------------------------
1 || category1 || NULL || 1
2 || subcategory1 || 1 || 1
Then i have my model code:
public function getCategories()
{
$results = $this->db->select('msi_items_categories','status = 1 AND parent_id = NULL');
if( !is_array($results[0]) ) {
$new_results = array();
array_push($new_results, $results);
return $new_results;
} else {
return $results;
}
}
public function getSubCategories($parent)
{
$bind = [':parent' => $parent];
$results = $this->db->select('msi_items_categories','status = 1 AND parent_id = :parent');
if( !is_array($results[0]) ) {
$new_results = array();
array_push($new_results, $results);
return $new_results;
} else {
return $results;
}
}
This is my controller code:
public function error()
{
$getSettings = $this->setting->getAll();
$getCategories = $this->setting->getCategories();
$getSubCategories = $this->setting->getSubCategories();
if(is_array($getCategories[0]) ) {
$isCategory = true;
} else {
$isCategory = false;
}
if(is_array($getSubCategories[0]) ) {
$isSubCategory = true;
} else {
$isSubCategory = false;
}
$data = [
'settings' => $getSettings,
'mainCategory' => $getCategories,
'subCategory' => $getSubCategories,
'isCategory' => $isCategory
'isSubCategory' => $isSubCategory
];
$this->view('index', $data);
}
Then I have my templatecode which is where im trying to do the foreach and the top category works fine but i just can't figure out how i do the subcategories. Before i started using the MVC model, i would simply just put the class inside the main category foreach and then put the id but now its all done in the controller so i cannot figure out how i do subcategories using the MVC model.
<?php foreach($data['mainCategory'] as $category) : ?>
<li class="dropdown">
<a class="dropdown-toggle nav-link dropdown-toggle pl-0" data-toggle="dropdown" aria-expanded="false" href="#"><?php echo $category['name']; ?></a>
<div class="dropdown-menu" role="menu">
<a class="dropdown-item" role="presentation" href="#"><i class="text-black-50 fas fa-box"></i> All <?php echo $category['name']; ?></a>
<div class="dropdown-divider" role="presentation"></div>
<?php foreach($data['subCategory'] as $scategory) : ?>
<a class="dropdown-item" role="presentation" href="#"><i class="text-black-50 <?php echo $scategory['icon']; ?>"></i> <?php echo $scategory['name']; ?></a>
<?php endforeach; ?>
</div>
</li>
<?php endforeach; ?>
Thanks very much!

Answer 1

$query = 'SELECT id, parent_id, name, icon FROM categories ORDER BY name';
$result = mysqli_query($conn, $query) OR trigger_error($query.'<br>'.mysqli_error($conn),E_USER_ERROR);
$refs = Array();
$categories = Array();
while($row = mysqli_fetch_assoc($result))
{
$thisref = &$refs[$row['id']];
$thisref['name'] = $row['name'];
$thisref['icon'] = $row['icon'];
if($row['parent_id']) $refs[$row['parent_id']]['children'][$row['id']] = &$thisref;
else $categories[$row['id']] = &$thisref;
}
echo '<ul class="nav navbar-nav mr-auto">';
foreach($categories as $category)
{
echo '<li class="dropdown">';
echo is_array($category['children'])
? '<a class="dropdown-toggle nav-link dropdown-toggle pl-0" data-toggle="dropdown" aria-expanded="false" href="#">'.$category['name'].'</a>'.sub($category['children'])
: $category['name'];
echo '</li>';
}
echo '</ul>';
function sub(&$subCat)
{
echo '<div class="dropdown-menu" role="menu">
<a class="dropdown-item hide-me" role="presentation" href="#"><i class="fas fa-fire mr-2"></i> Most Popular </a>
<div class="dropdown-divider hide-me" role="presentation"></div>';
foreach($subCat as $id => $subcategory)
{
echo '<a class="dropdown-item" role="presentation" href="'.FULL_ROOT.'/category/'.$id.'/"><i class="'.$subcategory['icon'].' mr-2"></i>'.$subcategory['name'].'</a>';
}
echo '</div>';
}