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Data Layer

Model categories and products with migrations and seeds.

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

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