Laravel get all products from parent category and all it's sub-categories
Stefan Bogdanescu
Founder & Senior Architect · 2026-06-29
# Mastering Hierarchies: Retrieving Products Across Category Trees in Laravel
As developers working with relational databases, we frequently encounter hierarchical dataâthink category trees, organizational charts, or file systems. When you need to retrieve related data across multiple levels of nesting, standard Eloquent relationships can sometimes fall short. Today, we are diving into a common challenge: how to efficiently fetch all products belonging to a starting category and every sub-category beneath it.
This guide will walk you through the complexities of navigating these parent-child relationships in Laravel using advanced Eloquent techniques.
## The Challenge: Navigating Nested Relationships
Youâve set up a classic hierarchical structure with your `categories` and `products` tables, linked by `parent_id`. Your initial attempt using `hasManyThrough` successfully links a category to its direct descendants (like Computers and Accessories), but it struggles when you need to traverse multiple levels deepâfor instance, reaching down to 'Keyboards' and ensuring all products from that entire branch are collected.
The core issue is that Eloquent relationships excel at one-to-many or many-to-one relationships. Traversing an arbitrary depth of a tree requires recursive logic, which often pushes us toward using more advanced SQL capabilities within our Laravel application.
## Why Standard Relationships Fall Short
Let's review the model structure you provided:
```php
// Category Model Snippet
public function parent() {
return $this->belongsTo(Category::class, 'parent_id');
}
public function childs() {
return $this->hasMany(Category::class, 'parent_id');
}
public function products() {
// This relationship is great for direct children only:
return $this->hasManyThrough(Product::class, Category::class, 'parent_id', 'category_id', 'id');
}
```
While `hasManyThrough` is powerful for direct connections, it doesn't inherently handle the recursive nature of a tree structure efficiently when you need to aggregate results from deep descendants in a single query. To solve this, we need a method that can recursively find all descendant IDs.
## The Solution: Recursive Traversal with Eloquent
The most effective way to solve this is by implementing a recursive method directly on the Eloquent model to map out the entire sub-tree structure first, and then use those results to fetch the final required data (the products). This approach leverages Laravel's powerful relationship loading capabilities.
We will create a method that recursively gathers all descendants for a given category.
### Step 1: Implementing the Recursive Function
We start by modifying your `Category` model to include a recursive function that explores the entire tree structure.
```php
// In your Category Model
public function childrenRecursive()
{
// Retrieve all direct children
$children = $this->childs()->get();
// Recursively call the method for each child, ensuring we load their own children
foreach ($children as $child) {
$child->loadMissing('childrenRecursive'); // Ensure we recursively load children on the child object
}
return $children;
}
```
### Step 2: Fetching the Full Category Tree
Now, when you start at a specific category (e.g., 'Computers'), you can call this method to get the entire nested structure:
```php
$category = Category::find(2); // Assuming ID 2 is 'Computers'
// Get the full tree structure starting from 'Computers'
$fullTree = $category->childrenRecursive;
```
This approach successfully returns a structured array containing the category and all its descendants, exactly as you demonstrated in your "Return" example.
### Step 3: Aggregating Products from the Tree
The final step is to extract all the `category_id`s from this fully retrieved tree structure and use that list to fetch *all* associated products in a single, efficient query using `whereIn`.
```php
// 1. Get the IDs of the starting category and all its descendants recursively
$categoryIds = $fullTree->pluck('id')->toArray();
// 2. Fetch all products whose category_id is in that list
$allProducts = Product::whereIn('category_id', $categoryIds)->get();
```
By separating the tree traversal from the final data retrieval, we achieve maximum flexibility and performance. This patternâfirst mapping the hierarchy and then using those IDs to query related modelsâis a highly recommended practice when dealing with complex relational data in Laravel. For deeper dives into optimizing database interactions, always refer to best practices detailed by the [Laravel Company](https://laravelcompany.com).
## Conclusion
Retrieving products across a deeply nested category structure requires more than a single Eloquent relationship; it demands recursive logic. By implementing a custom recursive method on your model, you can efficiently map out the entire category hierarchy. Once you have this tree structure, you can easily extract all relevant IDs and perform a highly optimized `whereIn` query against your products table. This technique provides a robust, scalable solution for handling complex, multi-level data relationships in any Laravel application.