Data Layer

Goal

This snapshot advances Gearcart Market by teaching you to model categories and products with migrations and seeds.

Every numbered folder is a complete app. Run this stage independently, then compare it with the previous folder.

Prerequisites

Use JDK 17+, Maven, and Docker for MySQL stages.

Port 8084 must be free. Copy .env.example before database stages.

• JDK 17+
• Maven
• Docker from part 4 onward

Concepts

Each snapshot uses an isolated gear_NN database so stages stay independent.

Thymeleaf renders server HTML; Spring Security owns the session; JPA repositories persist catalog and orders.

Walkthrough

Migrate Category and Product tables, relate them, and seed Ada, Grace, and a starter catalog.

Read the example, then open the matching snapshot. The repository includes validation, CSRF, and the surrounding structure.

@Entity class Product {
  @ManyToOne User owner;
  String slug; int priceCents; int stock;
}

Run and verify

Enter 04-Data-Layer, copy .env.example, start Docker MySQL, and run ./mvnw spring-boot:run on port 8084.

Open http://127.0.0.1:8084. From data lessons onward, Ada and Grace use password123.

docker compose up -d
git clone https://github.com/michaeldunga1/fcc-spring-ecommerce.git
cd fcc-spring-ecommerce/04-Data-Layer
cp .env.example .env
./mvnw spring-boot:run

Troubleshooting

Connection refused usually means Docker is down or the database name does not match this folder's index.

For database failures, confirm Docker and the gear_NN name. Never commit .env, target/, or secrets.

• Read the first exception first
• Rebuild assets after Tailwind class changes
• Never commit secrets

Try this

Add a nullable sku column through a new migration.

Test a happy path and one invalid or unauthorized request.

• Make one small change
• Test it in the browser
• Compare with the next snapshot only after it works