PHP foreach categories and subcategories - php

Question

I am working with my project that has a capabality in making categories and subcategories. What I've made in my database is that the subcategory column has a relationship to category_key column
Meaning, all records that doesn't have a value in subcategory column is considered as category, the rest are subcategory.
In the picture below:
b is a subcategory of a
e, g, h is a subcategory of d
And now I am using this code to diplay it in my page:
<?php
$query = "SELECT * FROM `categories`";
$result = mysql_query($query);
while($row = mysql_fetch_array($result)){
if(empty($row['subcategory'])){
echo '
<li class="dd-item dd3-item" id="'.$row['category_key'].'" data-name="'.$row['category_name'].'" data-key="'.$row['category_key'].'">
<div class="dd-handle dd3-handle">
<i class="fa fa-bars" aria-hidden="true"></i>
</div>
<div class="dd-edit other-handle edit">
<i class="fa fa-pencil" aria-hidden="true"></i>
</div>
<div class="dd-edit other-handle delete">
<i class="fa fa-trash" aria-hidden="true"></i>
</div>
<div class="dd3-content">'.$row['category_name'].'</div>
</li>
';
}else{
echo '
<ol class="dd-list">
<li class="dd-item dd3-item" id="'.$row['category_key'].'" data-name="'.$row['category_name'].'" data-key="'.$row['category_key'].'">
<div class="dd-handle dd3-handle">
<i class="fa fa-bars" aria-hidden="true"></i>
</div>
<div class="dd-edit other-handle edit">
<i class="fa fa-pencil" aria-hidden="true"></i>
</div>
<div class="dd-edit other-handle delete">
<i class="fa fa-trash" aria-hidden="true"></i>
</div>
<div class="dd3-content">'.$row['category_name'].'</div>
</li>
</ol>
';
}
}
?>
The problem is <ol> element is repeating as it must be only one and also it must be inside the parent <li> of it's category.
Any help?

Answer 1

You need to structure your result array first:
function appendChildren($input)
{
$output = [];
foreach($input as $value)
{
$key = $value["category_key"];
if(empty($input["subcategory"]))
{
$output[$key] = [];
$output[$key]["value"] = $value;
$output[$key]["children"] = [];
} else {
$parent_key = $value["subcategory"];
$output[$parent_key]["children"][] = $value;
}
}
return $output;
}
then you'll have an array like this:
|-- b
|-- a
|
|-- c
|-- d
|-- e
|-- g
|-- h
|
|-- f
Now, begins the formatting:
$input = [];
$query = "SELECT * FROM `categories`";
$result = mysql_query($query);
while($row = mysql_fetch_array($result)){
$input[] = $row;
}
$result = appendChildren($input);
foreach($result as $row)
{
// open <li> tag
if(count($row["children"]) > 0)
{
foreach($children as $child)
// add ordered list
}
// close <li> tag
}