How to create a nested-list of categories in Laravel?
Stefan Bogdanescu
Founder & Senior Architect · 2026-06-29
# How to Create a Nested List of Categories in Laravel
Creating nested data structures, such as hierarchical category lists, is a common requirement in web applications—think navigation menus, file explorers, or organizational charts. In Laravel, while the database structure handles the hierarchy beautifully, transforming that flat relational data into a nested structure for display requires thoughtful use of Eloquent relationships and PHP collection manipulation.
This guide will walk you through the best practices for structuring your category data in a Laravel application, moving beyond simple recursive functions to achieve a clean, scalable solution.
## 1. Establishing the Eloquent Foundation
The foundation of any complex relationship in Laravel lies in defining proper Eloquent relationships within your models. For a nested structure based on `parent_id`, you need a self-referencing relationship.
First, ensure your `Category` model has the necessary relationships defined. This allows Laravel to handle the complex joins automatically.
```php
// app/Models/Category.php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\HasMany;
class Category extends Model
{
protected $fillable = ['name', 'parent_id'];
/**
* Relationship to the parent category.
*/
public function parent(): BelongsTo
{
return $this->belongsTo(Category::class, 'parent_id');
}
/**
* Relationship to the direct children categories.
*/
public function children(): HasMany
{
return $this->hasMany(Category::class, 'parent_id');
}
}
```
By defining these relationships, you enable Eloquent to traverse the hierarchy efficiently, which is a core strength of using robust frameworks like Laravel.
## 2. The Challenge of Nesting: Why Recursion Isn't Ideal Here
You mentioned attempting a recursive function to build this structure. While recursion is mathematically sound for traversing trees, relying on deep, recursive calls within a standard controller or service layer can be inefficient, difficult to debug, and often results in overly complex data structures that are cumbersome to pass to the Blade view.
The issue with your provided recursive approach is that it forces the application logic (PHP) to do all the heavy lifting of grouping, rather than letting the database structure and Eloquent handle the initial relationship fetching.
## 3. The Recommended Approach: Collection Aggregation
The most performant and "Laravel-idiomatic" way to create a nested list is to fetch the data and then use PHP's powerful Collection methods to reorganize it into the desired nested format. This keeps your business logic separate from raw SQL manipulation.
Here is how you can fetch all categories and build the nested structure in your controller:
```php
use App\Models\Category;
use Illuminate\Http\Request;
class CategoryController extends Controller
{
public function index()
{
// 1. Fetch all categories
$categories = Category::all();
// 2. Build the nested structure using a helper function or collection grouping
$nestedCategories = $this->buildNestedList($categories);
return view('categories.index', compact('nestedCategories'));
}
/**
* Recursively builds the nested category structure.
*/
protected function buildNestedList(array $categories)
{
$categories = collect($categories);
// Group categories by their parent ID
$grouped = $categories->groupBy('parent_id');
$nestedList = [];
foreach ($grouped as $parentId => $children) {
// Find the parent category object to attach the children to
$parent = Category::find($parentId);
if ($parent) {
// If there are no children, treat it as a top-level item
if ($children->isEmpty()) {
$nestedList[] = [
'name' => $parent->name,
'children' => [],
];
} else {
// Otherwise, attach the children
$nestedList[] = [
'name' => $parent->name,
'children' => $this->buildNestedList($children->toArray()), // Recursive call for nesting
];
}
}
}
return $nestedList;
}
}
```
## 4. Adding Category Depth (Level) Information
You asked about adding a column like `depth`. This is an excellent idea, and it should be calculated during the data retrieval process rather than being stored permanently in the database, as depth is relative to the structure.
When implementing the aggregation logic above, you can easily calculate the depth within the recursive function or by using Laravel's collection methods to assign a level index during the grouping phase. For instance, when processing `$grouped`, the category with `parent_id` null is at depth 1, and its children are at depth 2, and so on. This calculated depth can then be easily passed directly to your view for styling purposes.
## Conclusion
By leveraging Eloquent relationships to define the parent/child links and utilizing Laravel's Collection features for data manipulation, you move away from brittle recursive functions toward a scalable, maintainable solution. This approach ensures that when you build complex data structures in Laravel, you are utilizing the framework's intended tools, making your code cleaner, more predictable, and easier to maintain—a hallmark of good development practices supported by systems like those found at https://laravelcompany.com.