Writing recursive functions

canobi

I'm trying to develop a function that will manage product categories in a simple e-commerce app.

I've created a categories table and each category has a parent category that identifies its origin. I developed a category class with a function whose aim is to collect all categories below a particular category and put the id values in an array, then return the array. Below is the syntax

function getAllSubCategories($category_group_id)
{
//compose query
$query01 = "SELECT categories_id ".
"FROM ".TABLE_CATEGORIES." ".
"WHERE (categories_id > 0) AND ".
"(parent_id = '".$category_group_id."') ".
"ORDER BY categories_id";

	//execute query
	$query_result = cj_db_query($query01, $link = 'db_link');

	//$notice = $this->checkIfSubCategoryExists($category_group_id);

	//get the category ids of sub categories
	while ($row = mysql_fetch_array($query_result, MYSQL_ASSOC))
	{
		$category_id = $row["categories_id"];

		//check if a subcategory exists for the category
		$notice = $this->checkIfSubCategoryExists($category_id);

		if ($notice = "yes")
		{
			$this->getAllSubCategories($category_id);					
		}
		else if ($notice = "no")
		{
			$this->category_tree_arr[] = $category_id;
		}
	}

	return $this->category_tree_arr;
}

It's a recursive function but I haven't been able to get it working properly.

I would really appreciate any tips on how to develop recursive functions since that's the only way I think it will work without overbloating the code.

Thanks a lot.

Weedpacket

Well, I can't run your code (it's incomplete and I don't have your database) or knowing what is happening that's wrong, I can only see a problem with the line

$this->getAllSubCategories($category_id);

It's the recursive call, but you're not doing anything with the returned subcategories. Where is the result of

return $this->category_tree_arr;

supposed to go?

canobi

Hi!

I only want the id of a category that has no subcategories. So from the conditional construct

if ($notice = "yes")
{
$this->getAllSubCategories($category_id);
}
else if ($notice = "no")
{
$this->category_tree_arr[] = $category_id;
}

I only populate the class array with a value if the category id has no subcategories within it. And finally, I want to return this class array which now has all the category ids within it.

However, since I'm returning the class array in the function, it's going to return the same class array when I do the recursion so I'm not sure if this is a good thing.

The class that contains this function is included into a .php page which gets all the values in the returned array, then uses them for additional chores.

Do you think there's a better way of going about this?

Thanks.