---
title: Cart Validation and Processing | Shopware Community Hub
description: >-
  Understand how carts are built, validated, recalculated, and converted into an
  order in Shopware.
canonical_url: 'https://hub.shopware.com/learn/course/cart-validation-processing'
---

# Cart Validation and Processing

<LearningObjectives>

- Understand Shopware's cart architecture: line items, deliveries, and price calculation.
- Explain when and why cart recalculation happens and how the pipeline is structured.
- Implement cart validation and surface blocking vs. non-blocking errors to the storefront.
- Extend cart calculation with focused custom processors.
- Debug and test cart behavior reliably using the Symfony profiler, logs, and tests.
  
</LearningObjectives>

# Cart Validation and Processing

This course introduces the core concepts of Shopware's cart system. You'll learn how carts are structured, when recalculation happens, and how Shopware validates and converts carts into orders during checkout.

By the end of this course, you'll understand where to hook in with custom logic (collectors, processors, validators), how to surface meaningful errors to customers, and how to distinguish between built-in promotions and custom discount implementations.

## Learning Approach

This course focuses on practical understanding. You will work with realistic examples to see how cart calculation, processing, and validation behave during checkout.

By the end of this course, you'll be able to reason about cart behavior, implement custom cart logic safely, and troubleshoot common cart-related issues.

## Example Plugin

Throughout this course, we'll use the **AcademyCartExamples** plugin as a running example.

### Getting the Plugin

```shell
cd custom/plugins
git clone https://github.com/ShopwareAcademy/AcademyCartExamples.git
```

## Learning Units

## Units
- [Cart Architecture and Recalculation](/learn/unit/cart-architecture-recalculation): Understand Shopware’s cart structure, line items, and how recalculation works.
- [Cart Processing Pipeline and Order Conversion](/learn/unit/cart-processing-pipeline-and-order-conversion): Understand how cart collectors, cart processors, and validators work together during cart recalculation and how the validated cart becomes the basis for order…
- [Cart Validation Strategies](/learn/unit/cart-validation-strategies): Implement custom cart validation to ensure data integrity and prevent invalid orders.
- [Cart Debugging and Troubleshooting](/learn/unit/cart-debugging-troubleshooting): Learn how to debug cart issues, analyze performance, and troubleshoot common checkout problems.
- [Cart: Promotions and Discounts](/learn/unit/cart-promotions-and-discounts): Learn how Shopware promotions are represented in the cart and how they differ from custom discount line items.